-Table of contents
------------------
+How fio works
+-------------
-1. Overview
-2. How fio works
-3. Running fio
-4. Job file format
-5. Detailed list of parameters
-6. Normal output
-7. Terse output
-8. Trace file format
-9. CPU idleness profiling
-10. Verification and triggers
-11. Log File Formats
-
-
-1.0 Overview and history
-------------------------
-fio was originally written to save me the hassle of writing special test
-case programs when I wanted to test a specific workload, either for
-performance reasons or to find/reproduce a bug. The process of writing
-such a test app can be tiresome, especially if you have to do it often.
-Hence I needed a tool that would be able to simulate a given io workload
-without resorting to writing a tailored test case again and again.
-
-A test work load is difficult to define, though. There can be any number
-of processes or threads involved, and they can each be using their own
-way of generating io. You could have someone dirtying large amounts of
-memory in an memory mapped file, or maybe several threads issuing
-reads using asynchronous io. fio needed to be flexible enough to
-simulate both of these cases, and many more.
-
-2.0 How fio works
------------------
-The first step in getting fio to simulate a desired io workload, is
-writing a job file describing that specific setup. A job file may contain
-any number of threads and/or files - the typical contents of the job file
-is a global section defining shared parameters, and one or more job
-sections describing the jobs involved. When run, fio parses this file
-and sets everything up as described. If we break down a job from top to
-bottom, it contains the following basic parameters:
+The first step in getting fio to simulate a desired I/O workload, is writing a
+job file describing that specific setup. A job file may contain any number of
+threads and/or files -- the typical contents of the job file is a *global*
+section defining shared parameters, and one or more job sections describing the
+jobs involved. When run, fio parses this file and sets everything up as
+described. If we break down a job from top to bottom, it contains the following
+basic parameters:
- IO type Defines the io pattern issued to the file(s).
- We may only be reading sequentially from this
- file(s), or we may be writing randomly. Or even
- mixing reads and writes, sequentially or randomly.
+`I/O type`_
- Block size In how large chunks are we issuing io? This may be
- a single value, or it may describe a range of
- block sizes.
+ Defines the I/O pattern issued to the file(s). We may only be reading
+ sequentially from this file(s), or we may be writing randomly. Or even
+ mixing reads and writes, sequentially or randomly.
+ Should we be doing buffered I/O, or direct/raw I/O?
- IO size How much data are we going to be reading/writing.
+`Block size`_
- IO engine How do we issue io? We could be memory mapping the
- file, we could be using regular read/write, we
- could be using splice, async io, or even SG
- (SCSI generic sg).
+ In how large chunks are we issuing I/O? This may be a single value,
+ or it may describe a range of block sizes.
- IO depth If the io engine is async, how large a queuing
- depth do we want to maintain?
+`I/O size`_
- IO type Should we be doing buffered io, or direct/raw io?
+ How much data are we going to be reading/writing.
- Num files How many files are we spreading the workload over.
+`I/O engine`_
- Num threads How many threads or processes should we spread
- this workload over.
+ How do we issue I/O? We could be memory mapping the file, we could be
+ using regular read/write, we could be using splice, async I/O, or even
+ SG (SCSI generic sg).
-The above are the basic parameters defined for a workload, in addition
-there's a multitude of parameters that modify other aspects of how this
-job behaves.
+`I/O depth`_
+ If the I/O engine is async, how large a queuing depth do we want to
+ maintain?
-3.0 Running fio
----------------
-See the README file for command line parameters, there are only a few
-of them.
-Running fio is normally the easiest part - you just give it the job file
-(or job files) as parameters:
+`Target file/device`_
-$ fio job_file
+ How many files are we spreading the workload over.
-and it will start doing what the job_file tells it to do. You can give
-more than one job file on the command line, fio will serialize the running
-of those files. Internally that is the same as using the 'stonewall'
-parameter described in the parameter section.
+`Threads, processes and job synchronization`_
-If the job file contains only one job, you may as well just give the
-parameters on the command line. The command line parameters are identical
-to the job parameters, with a few extra that control global parameters
-(see README). For example, for the job file parameter iodepth=2, the
-mirror command line option would be --iodepth 2 or --iodepth=2. You can
-also use the command line for giving more than one job entry. For each
---name option that fio sees, it will start a new job with that name.
-Command line entries following a --name entry will apply to that job,
-until there are no more entries or a new --name entry is seen. This is
-similar to the job file options, where each option applies to the current
-job until a new [] job entry is seen.
+ How many threads or processes should we spread this workload over.
-fio does not need to run as root, except if the files or devices specified
-in the job section requires that. Some other options may also be restricted,
-such as memory locking, io scheduler switching, and decreasing the nice value.
+The above are the basic parameters defined for a workload, in addition there's a
+multitude of parameters that modify other aspects of how this job behaves.
-4.0 Job file format
--------------------
-As previously described, fio accepts one or more job files describing
-what it is supposed to do. The job file format is the classic ini file,
-where the names enclosed in [] brackets define the job name. You are free
-to use any ascii name you want, except 'global' which has special meaning.
-A global section sets defaults for the jobs described in that file. A job
-may override a global section parameter, and a job file may even have
-several global sections if so desired. A job is only affected by a global
-section residing above it. If the first character in a line is a ';' or a
-'#', the entire line is discarded as a comment.
+Command line options
+--------------------
+
+.. option:: --debug=type
+
+ Enable verbose tracing of various fio actions. May be ``all`` for all types
+ or individual types separated by a comma (e.g. ``--debug=file,mem`` will
+ enable file and memory debugging). Currently, additional logging is
+ available for:
+
+ *process*
+ Dump info related to processes.
+ *file*
+ Dump info related to file actions.
+ *io*
+ Dump info related to I/O queuing.
+ *mem*
+ Dump info related to memory allocations.
+ *blktrace*
+ Dump info related to blktrace setup.
+ *verify*
+ Dump info related to I/O verification.
+ *all*
+ Enable all debug options.
+ *random*
+ Dump info related to random offset generation.
+ *parse*
+ Dump info related to option matching and parsing.
+ *diskutil*
+ Dump info related to disk utilization updates.
+ *job:x*
+ Dump info only related to job number x.
+ *mutex*
+ Dump info only related to mutex up/down ops.
+ *profile*
+ Dump info related to profile extensions.
+ *time*
+ Dump info related to internal time keeping.
+ *net*
+ Dump info related to networking connections.
+ *rate*
+ Dump info related to I/O rate switching.
+ *compress*
+ Dump info related to log compress/decompress.
+ *?* or *help*
+ Show available debug options.
+
+.. option:: --parse-only
+
+ Parse options only, don\'t start any I/O.
+
+.. option:: --output=filename
+
+ Write output to file `filename`.
+
+.. option:: --bandwidth-log
+
+ Generate aggregate bandwidth logs.
+
+.. option:: --minimal
+
+ Print statistics in a terse, semicolon-delimited format.
+
+.. option:: --append-terse
+
+ Print statistics in selected mode AND terse, semicolon-delimited format.
+ **deprecated**, use :option:`--output-format` instead to select multiple
+ formats.
+
+.. option:: --output-format=type
+
+ Set the reporting format to `normal`, `terse`, `json`, or `json+`. Multiple
+ formats can be selected, separated by a comma. `terse` is a CSV based
+ format. `json+` is like `json`, except it adds a full dump of the latency
+ buckets.
+
+.. option:: --terse-version=type
+
+ Set terse version output format (default 3, or 2 or 4 or 5).
+
+.. option:: --version
+
+ Print version info and exit.
+
+.. option:: --help
+
+ Print a summary of the command line options and exit.
+
+.. option:: --cpuclock-test
+
+ Perform test and validation of internal CPU clock.
+
+.. option:: --crctest=[test]
+
+ Test the speed of the built-in checksumming functions. If no argument is
+ given all of them are tested. Alternatively, a comma separated list can be passed, in
+ which case the given ones are tested.
+
+.. option:: --cmdhelp=command
+
+ Print help information for `command`. May be ``all`` for all commands.
+
+.. option:: --enghelp=[ioengine[,command]]
+
+ List all commands defined by :option:`ioengine`, or print help for `command`
+ defined by :option:`ioengine`. If no :option:`ioengine` is given, list all
+ available ioengines.
+
+.. option:: --showcmd=jobfile
+
+ Turn a job file into command line options.
+
+.. option:: --readonly
+
+ Turn on safety read-only checks, preventing writes. The ``--readonly``
+ option is an extra safety guard to prevent users from accidentally starting
+ a write workload when that is not desired. Fio will only write if
+ `rw=write/randwrite/rw/randrw` is given. This extra safety net can be used
+ as an extra precaution as ``--readonly`` will also enable a write check in
+ the I/O engine core to prevent writes due to unknown user space bug(s).
+
+.. option:: --eta=when
+
+ When real-time ETA estimate should be printed. May be `always`, `never` or
+ `auto`.
+
+.. option:: --eta-newline=time
+
+ Force a new line for every `time` period passed. When the unit is omitted,
+ the value is interpreted in seconds.
+
+.. option:: --status-interval=time
+
+ Force full status dump every `time` period passed. When the unit is
+ omitted, the value is interpreted in seconds.
+
+.. option:: --section=name
+
+ Only run specified section in job file. Multiple sections can be specified.
+ The ``--section`` option allows one to combine related jobs into one file.
+ E.g. one job file could define light, moderate, and heavy sections. Tell
+ fio to run only the "heavy" section by giving ``--section=heavy``
+ command line option. One can also specify the "write" operations in one
+ section and "verify" operation in another section. The ``--section`` option
+ only applies to job sections. The reserved *global* section is always
+ parsed and used.
+
+.. option:: --alloc-size=kb
+
+ Set the internal smalloc pool to this size in KiB. The
+ ``--alloc-size`` switch allows one to use a larger pool size for smalloc.
+ If running large jobs with randommap enabled, fio can run out of memory.
+ Smalloc is an internal allocator for shared structures from a fixed size
+ memory pool and can grow to 16 pools. The pool size defaults to 16MiB.
+
+ NOTE: While running :file:`.fio_smalloc.*` backing store files are visible
+ in :file:`/tmp`.
+
+.. option:: --warnings-fatal
+
+ All fio parser warnings are fatal, causing fio to exit with an
+ error.
+
+.. option:: --max-jobs=nr
+
+ Maximum number of threads/processes to support.
+
+.. option:: --server=args
+
+ Start a backend server, with `args` specifying what to listen to.
+ See `Client/Server`_ section.
+
+.. option:: --daemonize=pidfile
+
+ Background a fio server, writing the pid to the given `pidfile` file.
+
+.. option:: --client=hostname
+
+ Instead of running the jobs locally, send and run them on the given host or
+ set of hosts. See `Client/Server`_ section.
+
+.. option:: --remote-config=file
+
+ Tell fio server to load this local file.
+
+.. option:: --idle-prof=option
+
+ Report CPU idleness. *option* is one of the following:
+
+ **calibrate**
+ Run unit work calibration only and exit.
+
+ **system**
+ Show aggregate system idleness and unit work.
+
+ **percpu**
+ As **system** but also show per CPU idleness.
+
+.. option:: --inflate-log=log
+
+ Inflate and output compressed log.
+
+.. option:: --trigger-file=file
+
+ Execute trigger cmd when file exists.
+
+.. option:: --trigger-timeout=t
+
+ Execute trigger at this time.
+
+.. option:: --trigger=cmd
+
+ Set this command as local trigger.
+
+.. option:: --trigger-remote=cmd
+
+ Set this command as remote trigger.
+
+.. option:: --aux-path=path
+
+ Use this path for fio state generated files.
+
+Any parameters following the options will be assumed to be job files, unless
+they match a job file parameter. Multiple job files can be listed and each job
+file will be regarded as a separate group. Fio will :option:`stonewall`
+execution between each group.
+
+
+Job file format
+---------------
+
+As previously described, fio accepts one or more job files describing what it is
+supposed to do. The job file format is the classic ini file, where the names
+enclosed in [] brackets define the job name. You are free to use any ASCII name
+you want, except *global* which has special meaning. Following the job name is
+a sequence of zero or more parameters, one per line, that define the behavior of
+the job. If the first character in a line is a ';' or a '#', the entire line is
+discarded as a comment.
+
+A *global* section sets defaults for the jobs described in that file. A job may
+override a *global* section parameter, and a job file may even have several
+*global* sections if so desired. A job is only affected by a *global* section
+residing above it.
+
+The :option:`--cmdhelp` option also lists all options. If used with an `option`
+argument, :option:`--cmdhelp` will detail the given `option`.
+
+See the `examples/` directory for inspiration on how to write job files. Note
+the copyright and license requirements currently apply to `examples/` files.
So let's look at a really simple job file that defines two processes, each
-randomly reading from a 128MiB file.
+randomly reading from a 128MiB file:
+
+.. code-block:: ini
-; -- start job file --
-[global]
-rw=randread
-size=128m
+ ; -- start job file --
+ [global]
+ rw=randread
+ size=128m
-[job1]
+ [job1]
-[job2]
+ [job2]
-; -- end job file --
+ ; -- end job file --
-As you can see, the job file sections themselves are empty as all the
-described parameters are shared. As no filename= option is given, fio
-makes up a filename for each of the jobs as it sees fit. On the command
-line, this job would look as follows:
+As you can see, the job file sections themselves are empty as all the described
+parameters are shared. As no :option:`filename` option is given, fio makes up a
+`filename` for each of the jobs as it sees fit. On the command line, this job
+would look as follows::
$ fio --name=global --rw=randread --size=128m --name=job1 --name=job2
-Let's look at an example that has a number of processes writing randomly
-to files.
+Let's look at an example that has a number of processes writing randomly to
+files:
-; -- start job file --
-[random-writers]
-ioengine=libaio
-iodepth=4
-rw=randwrite
-bs=32k
-direct=0
-size=64m
-numjobs=4
+.. code-block:: ini
-; -- end job file --
+ ; -- start job file --
+ [random-writers]
+ ioengine=libaio
+ iodepth=4
+ rw=randwrite
+ bs=32k
+ direct=0
+ size=64m
+ numjobs=4
+ ; -- end job file --
-Here we have no global section, as we only have one job defined anyway.
-We want to use async io here, with a depth of 4 for each file. We also
-increased the buffer size used to 32KiB and define numjobs to 4 to
-fork 4 identical jobs. The result is 4 processes each randomly writing
-to their own 64MiB file. Instead of using the above job file, you could
-have given the parameters on the command line. For this case, you would
-specify:
+Here we have no *global* section, as we only have one job defined anyway. We
+want to use async I/O here, with a depth of 4 for each file. We also increased
+the buffer size used to 32KiB and define numjobs to 4 to fork 4 identical
+jobs. The result is 4 processes each randomly writing to their own 64MiB
+file. Instead of using the above job file, you could have given the parameters
+on the command line. For this case, you would specify::
$ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4
When fio is utilized as a basis of any reasonably large test suite, it might be
desirable to share a set of standardized settings across multiple job files.
Instead of copy/pasting such settings, any section may pull in an external
-.fio file with 'include filename' directive, as in the following example:
-
-; -- start job file including.fio --
-[global]
-filename=/tmp/test
-filesize=1m
-include glob-include.fio
-
-[test]
-rw=randread
-bs=4k
-time_based=1
-runtime=10
-include test-include.fio
-; -- end job file including.fio --
-
-; -- start job file glob-include.fio --
-thread=1
-group_reporting=1
-; -- end job file glob-include.fio --
-
-; -- start job file test-include.fio --
-ioengine=libaio
-iodepth=4
-; -- end job file test-include.fio --
-
-Settings pulled into a section apply to that section only (except global
-section). Include directives may be nested in that any included file may
-contain further include directive(s). Include files may not contain []
-sections.
-
-
-4.1 Environment variables
--------------------------
+:file:`filename.fio` file with *include filename* directive, as in the following
+example::
+
+ ; -- start job file including.fio --
+ [global]
+ filename=/tmp/test
+ filesize=1m
+ include glob-include.fio
+
+ [test]
+ rw=randread
+ bs=4k
+ time_based=1
+ runtime=10
+ include test-include.fio
+ ; -- end job file including.fio --
+
+.. code-block:: ini
+
+ ; -- start job file glob-include.fio --
+ thread=1
+ group_reporting=1
+ ; -- end job file glob-include.fio --
+
+.. code-block:: ini
+
+ ; -- start job file test-include.fio --
+ ioengine=libaio
+ iodepth=4
+ ; -- end job file test-include.fio --
+
+Settings pulled into a section apply to that section only (except *global*
+section). Include directives may be nested in that any included file may contain
+further include directive(s). Include files may not contain [] sections.
+
+
+Environment variables
+~~~~~~~~~~~~~~~~~~~~~
-fio also supports environment variable expansion in job files. Any
-sub-string of the form "${VARNAME}" as part of an option value (in other
-words, on the right of the `='), will be expanded to the value of the
-environment variable called VARNAME. If no such environment variable
-is defined, or VARNAME is the empty string, the empty string will be
-substituted.
+Fio also supports environment variable expansion in job files. Any sub-string of
+the form ``${VARNAME}`` as part of an option value (in other words, on the right
+of the '='), will be expanded to the value of the environment variable called
+`VARNAME`. If no such environment variable is defined, or `VARNAME` is the
+empty string, the empty string will be substituted.
-As an example, let's look at a sample fio invocation and job file:
+As an example, let's look at a sample fio invocation and job file::
$ SIZE=64m NUMJOBS=4 fio jobfile.fio
-; -- start job file --
-[random-writers]
-rw=randwrite
-size=${SIZE}
-numjobs=${NUMJOBS}
-; -- end job file --
+.. code-block:: ini
+
+ ; -- start job file --
+ [random-writers]
+ rw=randwrite
+ size=${SIZE}
+ numjobs=${NUMJOBS}
+ ; -- end job file --
This will expand to the following equivalent job file at runtime:
-; -- start job file --
-[random-writers]
-rw=randwrite
-size=64m
-numjobs=4
-; -- end job file --
+.. code-block:: ini
+
+ ; -- start job file --
+ [random-writers]
+ rw=randwrite
+ size=64m
+ numjobs=4
+ ; -- end job file --
-fio ships with a few example job files, you can also look there for
-inspiration.
+Fio ships with a few example job files, you can also look there for inspiration.
-4.2 Reserved keywords
----------------------
+Reserved keywords
+~~~~~~~~~~~~~~~~~
Additionally, fio has a set of reserved keywords that will be replaced
internally with the appropriate value. Those keywords are:
-$pagesize The architecture page size of the running system
-$mb_memory Megabytes of total memory in the system
-$ncpus Number of online available CPUs
+**$pagesize**
+
+ The architecture page size of the running system.
+
+**$mb_memory**
+
+ Megabytes of total memory in the system.
+
+**$ncpus**
+
+ Number of online available CPUs.
These can be used on the command line or in the job file, and will be
-automatically substituted with the current system values when the job
-is run. Simple math is also supported on these keywords, so you can
-perform actions like:
+automatically substituted with the current system values when the job is
+run. Simple math is also supported on these keywords, so you can perform actions
+like::
-size=8*$mb_memory
+ size=8*$mb_memory
-and get that properly expanded to 8 times the size of memory in the
-machine.
+and get that properly expanded to 8 times the size of memory in the machine.
-5.0 Detailed list of parameters
--------------------------------
+Job file parameters
+-------------------
-This section describes in details each parameter associated with a job.
-Some parameters take an option of a given type, such as an integer or
-a string. Anywhere a numeric value is required, an arithmetic expression
-may be used, provided it is surrounded by parentheses. Supported operators
-are:
+This section describes in details each parameter associated with a job. Some
+parameters take an option of a given type, such as an integer or a
+string. Anywhere a numeric value is required, an arithmetic expression may be
+used, provided it is surrounded by parentheses. Supported operators are:
- addition (+)
- subtraction (-)
- multiplication (*)
- division (/)
- modulus (%)
- exponentiation (^)
+ - addition (+)
+ - subtraction (-)
+ - multiplication (*)
+ - division (/)
+ - modulus (%)
+ - exponentiation (^)
For time values in expressions, units are microseconds by default. This is
different than for time values not in expressions (not enclosed in
parentheses). The following types are used:
-str String. This is a sequence of alpha characters.
-time Integer with possible time suffix. In seconds unless otherwise
- specified, use eg 10m for 10 minutes. Accepts s/m/h for seconds,
- minutes, and hours, and accepts 'ms' (or 'msec') for milliseconds,
- and 'us' (or 'usec') for microseconds.
-
-int Integer. A whole number value, which may contain an integer prefix
- and an integer suffix.
- [integer prefix]number[integer suffix]
-
- The optional integer prefix specifies the number's base. The default
- is decimal. 0x specifies hexadecimal.
-
- The optional integer suffix specifies the number's units, and includes
- an optional unit prefix and an optional unit. For quantities of data,
- the default unit is bytes. For quantities of time, the default unit
- is seconds.
-
- With kb_base=1000, fio follows international standards for unit prefixes.
- To specify power-of-10 decimal values defined in the International
- System of Units (SI):
- Ki means kilo (K) or 1000
- Mi means mega (M) or 1000**2
- Gi means giga (G) or 1000**3
- Ti means tera (T) or 1000**4
- Pi means peta (P) or 1000**5
+
+Parameter types
+~~~~~~~~~~~~~~~
+
+**str**
+ String. This is a sequence of alpha characters.
+
+**time**
+ Integer with possible time suffix. Without a unit value is interpreted as
+ seconds unless otherwise specified. Accepts a suffix of 'd' for days, 'h' for
+ hours, 'm' for minutes, 's' for seconds, 'ms' (or 'msec') for milliseconds and
+ 'us' (or 'usec') for microseconds. For example, use 10m for 10 minutes.
+
+.. _int:
+
+**int**
+ Integer. A whole number value, which may contain an integer prefix
+ and an integer suffix:
+
+ [*integer prefix*] **number** [*integer suffix*]
+
+ The optional *integer prefix* specifies the number's base. The default
+ is decimal. *0x* specifies hexadecimal.
+
+ The optional *integer suffix* specifies the number's units, and includes an
+ optional unit prefix and an optional unit. For quantities of data, the
+ default unit is bytes. For quantities of time, the default unit is seconds
+ unless otherwise specified.
+
+ With :option:`kb_base`\=1000, fio follows international standards for unit
+ prefixes. To specify power-of-10 decimal values defined in the
+ International System of Units (SI):
+
+ * *Ki* -- means kilo (K) or 1000
+ * *Mi* -- means mega (M) or 1000**2
+ * *Gi* -- means giga (G) or 1000**3
+ * *Ti* -- means tera (T) or 1000**4
+ * *Pi* -- means peta (P) or 1000**5
To specify power-of-2 binary values defined in IEC 80000-13:
- k means kibi (Ki) or 1024
- M means mebi (Mi) or 1024**2
- G means gibi (Gi) or 1024**3
- T means tebi (Ti) or 1024**4
- P means pebi (Pi) or 1024**5
-
- With kb_base=1024 (the default), the unit prefixes are opposite from
- those specified in the SI and IEC 80000-13 standards to provide
+
+ * *k* -- means kibi (Ki) or 1024
+ * *M* -- means mebi (Mi) or 1024**2
+ * *G* -- means gibi (Gi) or 1024**3
+ * *T* -- means tebi (Ti) or 1024**4
+ * *P* -- means pebi (Pi) or 1024**5
+
+ With :option:`kb_base`\=1024 (the default), the unit prefixes are opposite
+ from those specified in the SI and IEC 80000-13 standards to provide
compatibility with old scripts. For example, 4k means 4096.
For quantities of data, an optional unit of 'B' may be included
(e.g., 'kB' is the same as 'k').
- The integer suffix is not case sensitive (e.g., m/mi mean mebi/mega,
+ The *integer suffix* is not case sensitive (e.g., m/mi mean mebi/mega,
not milli). 'b' and 'B' both mean byte, not bit.
- Examples with kb_base=1000:
- 4 KiB: 4096, 4096b, 4096B, 4ki, 4kib, 4kiB, 4Ki, 4KiB
- 1 MiB: 1048576, 1mi, 1024ki
- 1 MB: 1000000, 1m, 1000k
- 1 TiB: 1073741824, 1ti, 1024mi, 1048576ki
- 1 TB: 1000000000, 1t, 1000m, 1000000k
+ Examples with :option:`kb_base`\=1000:
- Examples with kb_base=1024 (default):
- 4 KiB: 4096, 4096b, 4096B, 4k, 4kb, 4kB, 4K, 4KB
- 1 MiB: 1048576, 1m, 1024k
- 1 MB: 1000000, 1mi, 1000ki
- 1 TiB: 1073741824, 1t, 1024m, 1048576k
- 1 TB: 1000000000, 1ti, 1000mi, 1000000ki
+ * *4 KiB*: 4096, 4096b, 4096B, 4ki, 4kib, 4kiB, 4Ki, 4KiB
+ * *1 MiB*: 1048576, 1mi, 1024ki
+ * *1 MB*: 1000000, 1m, 1000k
+ * *1 TiB*: 1099511627776, 1ti, 1024gi, 1048576mi
+ * *1 TB*: 1000000000, 1t, 1000m, 1000000k
+
+ Examples with :option:`kb_base`\=1024 (default):
+
+ * *4 KiB*: 4096, 4096b, 4096B, 4k, 4kb, 4kB, 4K, 4KB
+ * *1 MiB*: 1048576, 1m, 1024k
+ * *1 MB*: 1000000, 1mi, 1000ki
+ * *1 TiB*: 1099511627776, 1t, 1024g, 1048576m
+ * *1 TB*: 1000000000, 1ti, 1000mi, 1000000ki
To specify times (units are not case sensitive):
- D means days
- H means hours
- M mean minutes
- s or sec means seconds (default)
- ms or msec means milliseconds
- us or usec means microseconds
+
+ * *D* -- means days
+ * *H* -- means hours
+ * *M* -- means minutes
+ * *s* -- or sec means seconds (default)
+ * *ms* -- or *msec* means milliseconds
+ * *us* -- or *usec* means microseconds
If the option accepts an upper and lower range, use a colon ':' or
- minus '-' to separate such values. See irange.
+ minus '-' to separate such values. See :ref:`irange <irange>`.
+ If the lower value specified happens to be larger than the upper value
+ the two values are swapped.
+
+.. _bool:
-bool Boolean. Usually parsed as an integer, however only defined for
+**bool**
+ Boolean. Usually parsed as an integer, however only defined for
true and false (1 and 0).
-irange Integer range with suffix. Allows value range to be given, such
- as 1024-4096. A colon may also be used as the separator, eg
- 1k:4k. If the option allows two sets of ranges, they can be
- specified with a ',' or '/' delimiter: 1k-4k/8k-32k. Also see
- int.
-float_list A list of floating point numbers, separated by a ':' character.
-
-With the above in mind, here follows the complete list of fio job
-parameters.
-
-name=str ASCII name of the job. This may be used to override the
- name printed by fio for this job. Otherwise the job
- name is used. On the command line this parameter has the
- special purpose of also signaling the start of a new
- job.
-
-wait_for=str Specifies the name of the already defined job to wait
- for. Single waitee name only may be specified. If set, the job
- won't be started until all workers of the waitee job are done.
-
- Wait_for operates on the job name basis, so there are a few
- limitations. First, the waitee must be defined prior to the
- waiter job (meaning no forward references). Second, if a job
- is being referenced as a waitee, it must have a unique name
- (no duplicate waitees).
-
-description=str Text description of the job. Doesn't do anything except
- dump this text description when this job is run. It's
- not parsed.
-
-directory=str Prefix filenames with this directory. Used to place files
- in a different location than "./". See the 'filename' option
- for escaping certain characters.
-
-filename=str Fio normally makes up a filename based on the job name,
- thread number, and file number. If you want to share
- files between threads in a job or several jobs, specify
- a filename for each of them to override the default.
- If the ioengine is file based, you can specify a number of
- files by separating the names with a ':' colon. So if you
- wanted a job to open /dev/sda and /dev/sdb as the two working
- files, you would use filename=/dev/sda:/dev/sdb. On Windows,
- disk devices are accessed as \\.\PhysicalDrive0 for the first
- device, \\.\PhysicalDrive1 for the second etc. Note: Windows
- and FreeBSD prevent write access to areas of the disk
- containing in-use data (e.g. filesystems).
- If the wanted filename does need to include a colon, then
- escape that with a '\' character. For instance, if the filename
- is "/dev/dsk/foo@3,0:c", then you would use
- filename="/dev/dsk/foo@3,0\:c". '-' is a reserved name, meaning
- stdin or stdout. Which of the two depends on the read/write
- direction set.
-
-filename_format=str
- If sharing multiple files between jobs, it is usually necessary
- to have fio generate the exact names that you want. By default,
- fio will name a file based on the default file format
- specification of jobname.jobnumber.filenumber. With this
- option, that can be customized. Fio will recognize and replace
- the following keywords in this string:
-
- $jobname
- The name of the worker thread or process.
-
- $jobnum
- The incremental number of the worker thread or
- process.
-
- $filenum
- The incremental number of the file for that worker
- thread or process.
-
- To have dependent jobs share a set of files, this option can
- be set to have fio generate filenames that are shared between
- the two. For instance, if testfiles.$filenum is specified,
- file number 4 for any job will be named testfiles.4. The
- default of $jobname.$jobnum.$filenum will be used if
- no other format specifier is given.
-
-unique_filename=bool To avoid collisions between networked clients, fio
- defaults to prefixing any generated filenames (with a directory
- specified) with the source of the client connecting. To disable
- this behavior, set this option to 0.
-
-opendir=str Tell fio to recursively add any file it can find in this
- directory and down the file system tree.
-
-lockfile=str Fio defaults to not locking any files before it does
- IO to them. If a file or file descriptor is shared, fio
- can serialize IO to that file to make the end result
- consistent. This is usual for emulating real workloads that
- share files. The lock modes are:
-
- none No locking. The default.
- exclusive Only one thread/process may do IO,
- excluding all others.
- readwrite Read-write locking on the file. Many
- readers may access the file at the
- same time, but writes get exclusive
- access.
-
-readwrite=str
-rw=str Type of io pattern. Accepted values are:
-
- read Sequential reads
- write Sequential writes
- trim Sequential trims
- randwrite Random writes
- randread Random reads
- randtrim Random trims
- rw,readwrite Sequential mixed reads and writes
- randrw Random mixed reads and writes
- trimwrite Sequential trim+write sequences
-
- Fio defaults to read if the option is not specified.
- For the mixed io types, the default is to split them 50/50.
- For certain types of io the result may still be skewed a bit,
- since the speed may be different. It is possible to specify
- a number of IO's to do before getting a new offset, this is
- done by appending a ':<nr>' to the end of the string given.
- For a random read, it would look like 'rw=randread:8' for
- passing in an offset modifier with a value of 8. If the
- suffix is used with a sequential IO pattern, then the value
- specified will be added to the generated offset for each IO.
- For instance, using rw=write:4k will skip 4k for every
- write. It turns sequential IO into sequential IO with holes.
- See the 'rw_sequencer' option.
-
-rw_sequencer=str If an offset modifier is given by appending a number to
- the rw=<str> line, then this option controls how that
- number modifies the IO offset being generated. Accepted
- values are:
-
- sequential Generate sequential offset
- identical Generate the same offset
-
- 'sequential' is only useful for random IO, where fio would
- normally generate a new random offset for every IO. If you
- append eg 8 to randread, you would get a new random offset for
- every 8 IO's. The result would be a seek for only every 8
- IO's, instead of for every IO. Use rw=randread:8 to specify
- that. As sequential IO is already sequential, setting
- 'sequential' for that would not result in any differences.
- 'identical' behaves in a similar fashion, except it sends
- the same offset 8 number of times before generating a new
- offset.
-
-kb_base=int Select the interpretation of unit prefixes in input parameters.
- 1000 = Inputs comply with IEC 80000-13 and the International
- System of Units (SI). Use:
- - power-of-2 values with IEC prefixes (e.g., KiB)
- - power-of-10 values with SI prefixes (e.g., kB)
- 1024 = Compatibility mode (default). To avoid breaking
- old scripts:
- - power-of-2 values with SI prefixes
- - power-of-10 values with IEC prefixes
- See bs= for more details on input parameters.
-
- Outputs always use correct prefixes. Most outputs include
- both side-by-side, like:
- bw=2383.3kB/s (2327.4KiB/s)
- If only one value is reported, then kb_base selects the
- one to use:
- 1000 = SI prefixes
- 1024 = IEC prefixes
-
-unified_rw_reporting=bool Fio normally reports statistics on a per
- data direction basis, meaning that reads, writes, and trims are
- accounted and reported separately. If this option is set,
- the fio will sum the results and report them as "mixed"
- instead.
-
-randrepeat=bool For random IO workloads, seed the generator in a predictable
- way so that results are repeatable across repetitions.
- Defaults to true.
-
-randseed=int Seed the random number generators based on this seed value, to
- be able to control what sequence of output is being generated.
- If not set, the random sequence depends on the randrepeat
- setting.
-
-fallocate=str Whether pre-allocation is performed when laying down files.
- Accepted values are:
-
- none Do not pre-allocate space
- posix Pre-allocate via posix_fallocate()
- keep Pre-allocate via fallocate() with
- FALLOC_FL_KEEP_SIZE set
- 0 Backward-compatible alias for 'none'
- 1 Backward-compatible alias for 'posix'
-
- May not be available on all supported platforms. 'keep' is only
- available on Linux.If using ZFS on Solaris this must be set to
- 'none' because ZFS doesn't support it. Default: 'posix'.
-
-fadvise_hint=bool By default, fio will use fadvise() to advise the kernel
- on what IO patterns it is likely to issue. Sometimes you
- want to test specific IO patterns without telling the
- kernel about it, in which case you can disable this option.
- The following options are supported:
-
- sequential Use FADV_SEQUENTIAL
- random Use FADV_RANDOM
- 1 Backwards-compatible hint for basing
- the hint on the fio workload. Will use
- FADV_SEQUENTIAL for a sequential
- workload, and FADV_RANDOM for a random
- workload.
- 0 Backwards-compatible setting for not
- issing a fadvise hint.
-
-fadvise_stream=int Notify the kernel what write stream ID to place these
- writes under. Only supported on Linux. Note, this option
- may change going forward.
-
-size=int The total size of file io for this job. Fio will run until
- this many bytes has been transferred, unless runtime is
- limited by other options (such as 'runtime', for instance,
- or increased/decreased by 'io_size'). Unless specific nrfiles
- and filesize options are given, fio will divide this size
- between the available files specified by the job. If not set,
- fio will use the full size of the given files or devices.
- If the files do not exist, size must be given. It is also
- possible to give size as a percentage between 1 and 100. If
- size=20% is given, fio will use 20% of the full size of the
- given files or devices.
-
-io_size=int
-io_limit=int Normally fio operates within the region set by 'size', which
- means that the 'size' option sets both the region and size of
- IO to be performed. Sometimes that is not what you want. With
- this option, it is possible to define just the amount of IO
- that fio should do. For instance, if 'size' is set to 20GiB and
- 'io_size' is set to 5GiB, fio will perform IO within the first
- 20GiB but exit when 5GiB have been done. The opposite is also
- possible - if 'size' is set to 20GiB, and 'io_size' is set to
- 40GiB, then fio will do 40GiB of IO within the 0..20GiB region.
-
-filesize=int Individual file sizes. May be a range, in which case fio
- will select sizes for files at random within the given range
- and limited to 'size' in total (if that is given). If not
- given, each created file is the same size.
-
-file_append=bool Perform IO after the end of the file. Normally fio will
- operate within the size of a file. If this option is set, then
- fio will append to the file instead. This has identical
- behavior to setting offset to the size of a file. This option
- is ignored on non-regular files.
-
-fill_device=bool
-fill_fs=bool Sets size to something really large and waits for ENOSPC (no
- space left on device) as the terminating condition. Only makes
- sense with sequential write. For a read workload, the mount
- point will be filled first then IO started on the result. This
- option doesn't make sense if operating on a raw device node,
- since the size of that is already known by the file system.
- Additionally, writing beyond end-of-device will not return
- ENOSPC there.
-
-blocksize=int[,int][,int]
-bs=int[,int][,int]
- The block size in bytes used for I/O units. Default: 4096.
- A single value applies to reads, writes, and trims.
- Comma-separated values may be specified for reads, writes,
- and trims. A value not terminated in a comma applies to
- subsequent types.
-
- Examples:
- bs=256k means 256k for reads, writes and trims
- bs=8k,32k means 8k for reads, 32k for writes and trims
- bs=8k,32k, means 8k for reads, 32k for writes, and
- default for trims
- bs=,8k means default for reads, 8k for writes and trims
- bs=,8k, means default for reads, 8k for writes, and
- default for writes
-
-blocksize_range=irange[,irange][,irange]
-bsrange=irange[,irange][,irange]
- A range of block sizes in bytes for I/O units.
- The issued I/O unit will always be a multiple of the minimum
- size, unless blocksize_unaligned is set.
-
- Comma-separated ranges may be specified for reads, writes,
- and trims as described in 'blocksize'.
-
- Example: bsrange=1k-4k,2k-8k
-
-bssplit=str[,str][,str]
- Sometimes you want even finer grained control of the
- block sizes issued, not just an even split between them.
- This option allows you to weight various block sizes,
- so that you are able to define a specific amount of
- block sizes issued. The format for this option is:
-
- bssplit=blocksize/percentage:blocksize/percentage
-
- for as many block sizes as needed. So if you want to define
- a workload that has 50% 64k blocks, 10% 4k blocks, and
- 40% 32k blocks, you would write:
-
- bssplit=4k/10:64k/50:32k/40
-
- Ordering does not matter. If the percentage is left blank,
- fio will fill in the remaining values evenly. So a bssplit
- option like this one:
-
- bssplit=4k/50:1k/:32k/
-
- would have 50% 4k ios, and 25% 1k and 32k ios. The percentages
- always add up to 100, if bssplit is given a range that adds
- up to more, it will error out.
-
- Comma-separated values may be specified for reads, writes,
- and trims as described in 'blocksize'.
-
- If you want a workload that has 50% 2k reads and 50% 4k reads,
- while having 90% 4k writes and 10% 8k writes, you would
- specify:
-
- bssplit=2k/50:4k/50,4k/90:8k/10
-
-blocksize_unaligned
-bs_unaligned If set, fio will issue I/O units with any size within
- blocksize_range, not just multiples of the minimum size.
- This typically won't work with direct I/O, as that normally
- requires sector alignment.
-
-bs_is_seq_rand If this option is set, fio will use the normal read,write
- blocksize settings as sequential,random blocksize settings
- instead. Any random read or write will use the WRITE blocksize
- settings, and any sequential read or write will use the READ
- blocksize settings.
-
-blockalign=int[,int][,int]
-ba=int[,int][,int]
- Boundary to which fio will align random I/O units.
- Default: 'blocksize'.
- Minimum alignment is typically 512b for using direct IO,
- though it usually depends on the hardware block size. This
- option is mutually exclusive with using a random map for
- files, so it will turn off that option.
- Comma-separated values may be specified for reads, writes,
- and trims as described in 'blocksize'.
-
-zero_buffers If this option is given, fio will init the IO buffers to
- all zeroes. The default is to fill them with random data.
-
-refill_buffers If this option is given, fio will refill the IO buffers
- on every submit. The default is to only fill it at init
- time and reuse that data. Only makes sense if zero_buffers
- isn't specified, naturally. If data verification is enabled,
- refill_buffers is also automatically enabled.
-
-scramble_buffers=bool If refill_buffers is too costly and the target is
- using data deduplication, then setting this option will
- slightly modify the IO buffer contents to defeat normal
- de-dupe attempts. This is not enough to defeat more clever
- block compression attempts, but it will stop naive dedupe of
- blocks. Default: true.
-
-buffer_compress_percentage=int If this is set, then fio will attempt to
- provide IO buffer content (on WRITEs) that compress to
- the specified level. Fio does this by providing a mix of
- random data and a fixed pattern. The fixed pattern is either
- zeroes, or the pattern specified by buffer_pattern. If the
- pattern option is used, it might skew the compression ratio
- slightly. Note that this is per block size unit, for file/disk
- wide compression level that matches this setting, you'll also
- want to set refill_buffers.
-
-buffer_compress_chunk=int See buffer_compress_percentage. This
- setting allows fio to manage how big the ranges of random
- data and zeroed data is. Without this set, fio will
- provide buffer_compress_percentage of blocksize random
- data, followed by the remaining zeroed. With this set
- to some chunk size smaller than the block size, fio can
- alternate random and zeroed data throughout the IO
- buffer.
-
-buffer_pattern=str If set, fio will fill the io buffers with this
- pattern. If not set, the contents of io buffers is defined by
- the other options related to buffer contents. The setting can
- be any pattern of bytes, and can be prefixed with 0x for hex
- values. It may also be a string, where the string must then
- be wrapped with "", e.g.:
- buffer_pattern="abcd"
- or
- buffer_pattern=-12
- or
- buffer_pattern=0xdeadface
+.. _irange:
- Also you can combine everything together in any order:
- buffer_pattern=0xdeadface"abcd"-12
+**irange**
+ Integer range with suffix. Allows value range to be given, such as
+ 1024-4096. A colon may also be used as the separator, e.g. 1k:4k. If the
+ option allows two sets of ranges, they can be specified with a ',' or '/'
+ delimiter: 1k-4k/8k-32k. Also see :ref:`int <int>`.
-dedupe_percentage=int If set, fio will generate this percentage of
- identical buffers when writing. These buffers will be
- naturally dedupable. The contents of the buffers depend on
- what other buffer compression settings have been set. It's
- possible to have the individual buffers either fully
- compressible, or not at all. This option only controls the
- distribution of unique buffers.
+**float_list**
+ A list of floating point numbers, separated by a ':' character.
-nrfiles=int Number of files to use for this job. Defaults to 1.
-openfiles=int Number of files to keep open at the same time. Defaults to
- the same as nrfiles, can be set smaller to limit the number
- simultaneous opens.
+Units
+~~~~~
-file_service_type=str Defines how fio decides which file from a job to
- service next. The following types are defined:
+.. option:: kb_base=int
- random Just choose a file at random.
+ Select the interpretation of unit prefixes in input parameters.
- roundrobin Round robin over open files. This
- is the default.
+ **1000**
+ Inputs comply with IEC 80000-13 and the International
+ System of Units (SI). Use:
- sequential Finish one file before moving on to
- the next. Multiple files can still be
- open depending on 'openfiles'.
+ - power-of-2 values with IEC prefixes (e.g., KiB)
+ - power-of-10 values with SI prefixes (e.g., kB)
- zipf Use a zipfian distribution to decide what file
- to access.
+ **1024**
+ Compatibility mode (default). To avoid breaking old scripts:
- pareto Use a pareto distribution to decide what file
- to access.
+ - power-of-2 values with SI prefixes
+ - power-of-10 values with IEC prefixes
- gauss Use a gaussian (normal) distribution to decide
- what file to access.
+ See :option:`bs` for more details on input parameters.
- For random, roundrobin, and sequential, a postfix can be
- appended to tell fio how many I/Os to issue before switching
- to a new file. For example, specifying
- 'file_service_type=random:8' would cause fio to issue 8 I/Os
- before selecting a new file at random. For the non-uniform
- distributions, a floating point postfix can be given to
- influence how the distribution is skewed. See
- 'random_distribution' for a description of how that would work.
+ Outputs always use correct prefixes. Most outputs include both
+ side-by-side, like::
-ioengine=str Defines how the job issues io to the file. The following
- types are defined:
+ bw=2383.3kB/s (2327.4KiB/s)
- sync Basic read(2) or write(2) io. lseek(2) is
- used to position the io location.
+ If only one value is reported, then kb_base selects the one to use:
- psync Basic pread(2) or pwrite(2) io. Default on all
- supported operating systems except for Windows.
+ **1000** -- SI prefixes
- vsync Basic readv(2) or writev(2) IO.
+ **1024** -- IEC prefixes
- pvsync Basic preadv(2) or pwritev(2) IO.
-
- pvsync2 Basic preadv2(2) or pwritev2(2) IO.
+.. option:: unit_base=int
- libaio Linux native asynchronous io. Note that Linux
- may only support queued behaviour with
- non-buffered IO (set direct=1 or buffered=0).
- This engine defines engine specific options.
-
- posixaio glibc posix asynchronous io.
-
- solarisaio Solaris native asynchronous io.
-
- windowsaio Windows native asynchronous io.
- Default on Windows.
-
- mmap File is memory mapped and data copied
- to/from using memcpy(3).
-
- splice splice(2) is used to transfer the data and
- vmsplice(2) to transfer data from user
- space to the kernel.
-
- sg SCSI generic sg v3 io. May either be
- synchronous using the SG_IO ioctl, or if
- the target is an sg character device
- we use read(2) and write(2) for asynchronous
- io. Requires filename option to specify either
- block or character devices.
-
- null Doesn't transfer any data, just pretends
- to. This is mainly used to exercise fio
- itself and for debugging/testing purposes.
-
- net Transfer over the network to given host:port.
- Depending on the protocol used, the hostname,
- port, listen and filename options are used to
- specify what sort of connection to make, while
- the protocol option determines which protocol
- will be used.
- This engine defines engine specific options.
-
- netsplice Like net, but uses splice/vmsplice to
- map data and send/receive.
- This engine defines engine specific options.
-
- cpuio Doesn't transfer any data, but burns CPU
- cycles according to the cpuload= and
- cpuchunks= options. Setting cpuload=85
- will cause that job to do nothing but burn
- 85% of the CPU. In case of SMP machines,
- use numjobs=<no_of_cpu> to get desired CPU
- usage, as the cpuload only loads a single
- CPU at the desired rate. A job never finishes
- unless there is at least one non-cpuio job.
-
- guasi The GUASI IO engine is the Generic Userspace
- Asyncronous Syscall Interface approach
- to async IO. See
-
- http://www.xmailserver.org/guasi-lib.html
-
- for more info on GUASI.
-
- rdma The RDMA I/O engine supports both RDMA
- memory semantics (RDMA_WRITE/RDMA_READ) and
- channel semantics (Send/Recv) for the
- InfiniBand, RoCE and iWARP protocols.
-
- falloc IO engine that does regular fallocate to
- simulate data transfer as fio ioengine.
- DDIR_READ does fallocate(,mode = keep_size,)
- DDIR_WRITE does fallocate(,mode = 0)
- DDIR_TRIM does fallocate(,mode = punch_hole)
-
- e4defrag IO engine that does regular EXT4_IOC_MOVE_EXT
- ioctls to simulate defragment activity in
- request to DDIR_WRITE event
-
- rbd IO engine supporting direct access to Ceph
- Rados Block Devices (RBD) via librbd without
- the need to use the kernel rbd driver. This
- ioengine defines engine specific options.
-
- gfapi Using Glusterfs libgfapi sync interface to
- direct access to Glusterfs volumes without
- options.
-
- gfapi_async Using Glusterfs libgfapi async interface
- to direct access to Glusterfs volumes without
- having to go through FUSE. This ioengine
- defines engine specific options.
-
- libhdfs Read and write through Hadoop (HDFS).
- This engine interprets offsets a little
- differently. In HDFS, files once created
- cannot be modified. So random writes are not
- possible. To imitate this, libhdfs engine
- creates bunch of small files, and engine will
- pick a file out of those files based on the
- offset generated by fio backend. Each jobs uses
- it's own connection to HDFS.
-
- mtd Read, write and erase an MTD character device
- (e.g., /dev/mtd0). Discards are treated as
- erases. Depending on the underlying device
- type, the I/O may have to go in a certain
- pattern, e.g., on NAND, writing sequentially
- to erase blocks and discarding before
- overwriting. The writetrim mode works well
- for this constraint.
-
- pmemblk Read and write using filesystem DAX to a file
- on a filesystem mounted with DAX on a persistent
- memory device through the NVML libpmemblk library.
-
- dev-dax Read and write using device DAX to a persistent
- memory device (e.g., /dev/dax0.0) through the
- NVML libpmem library.
-
- external Prefix to specify loading an external
- IO engine object file. Append the engine
- filename, eg ioengine=external:/tmp/foo.o
- to load ioengine foo.o in /tmp.
-
-iodepth=int This defines how many I/O units to keep in flight against
- the file. The default is 1 for each file defined in this
- job, can be overridden with a larger value for higher
- concurrency. Note that increasing iodepth beyond 1 will not
- affect synchronous ioengines (except for small degress when
- verify_async is in use). Even async engines may impose OS
- restrictions causing the desired depth not to be achieved.
- This may happen on Linux when using libaio and not setting
- direct=1, since buffered IO is not async on that OS. Keep an
- eye on the IO depth distribution in the fio output to verify
- that the achieved depth is as expected. Default: 1.
-
-iodepth_batch_submit=int
-iodepth_batch=int This defines how many pieces of IO to submit at once.
- It defaults to 1 which means that we submit each IO
- as soon as it is available, but can be raised to submit
- bigger batches of IO at the time. If it is set to 0 the iodepth
- value will be used.
-
-iodepth_batch_complete_min=int
-iodepth_batch_complete=int This defines how many pieces of IO to retrieve
- at once. It defaults to 1 which means that we'll ask
- for a minimum of 1 IO in the retrieval process from
- the kernel. The IO retrieval will go on until we
- hit the limit set by iodepth_low. If this variable is
- set to 0, then fio will always check for completed
- events before queuing more IO. This helps reduce
- IO latency, at the cost of more retrieval system calls.
-
-iodepth_batch_complete_max=int This defines maximum pieces of IO to
- retrieve at once. This variable should be used along with
- iodepth_batch_complete_min=int variable, specifying the range
- of min and max amount of IO which should be retrieved. By default
- it is equal to iodepth_batch_complete_min value.
-
- Example #1:
+ Base unit for reporting. Allowed values are:
- iodepth_batch_complete_min=1
- iodepth_batch_complete_max=<iodepth>
+ **0**
+ Use auto-detection (default).
+ **8**
+ Byte based.
+ **1**
+ Bit based.
- which means that we will retrieve at least 1 IO and up to the
- whole submitted queue depth. If none of IO has been completed
- yet, we will wait.
- Example #2:
+With the above in mind, here follows the complete list of fio job parameters.
- iodepth_batch_complete_min=0
- iodepth_batch_complete_max=<iodepth>
- which means that we can retrieve up to the whole submitted
- queue depth, but if none of IO has been completed yet, we will
- NOT wait and immediately exit the system call. In this example
- we simply do polling.
-
-iodepth_low=int The low water mark indicating when to start filling
- the queue again. Defaults to the same as iodepth, meaning
- that fio will attempt to keep the queue full at all times.
- If iodepth is set to eg 16 and iodepth_low is set to 4, then
- after fio has filled the queue of 16 requests, it will let
- the depth drain down to 4 before starting to fill it again.
-
-io_submit_mode=str This option controls how fio submits the IO to
- the IO engine. The default is 'inline', which means that the
- fio job threads submit and reap IO directly. If set to
- 'offload', the job threads will offload IO submission to a
- dedicated pool of IO threads. This requires some coordination
- and thus has a bit of extra overhead, especially for lower
- queue depth IO where it can increase latencies. The benefit
- is that fio can manage submission rates independently of
- the device completion rates. This avoids skewed latency
- reporting if IO gets back up on the device side (the
- coordinated omission problem).
-
-direct=bool If value is true, use non-buffered io. This is usually
- O_DIRECT. Note that ZFS on Solaris doesn't support direct io.
- On Windows the synchronous ioengines don't support direct io.
-
-atomic=bool If value is true, attempt to use atomic direct IO. Atomic
- writes are guaranteed to be stable once acknowledged by
- the operating system. Only Linux supports O_ATOMIC right
- now.
-
-buffered=bool If value is true, use buffered io. This is the opposite
- of the 'direct' option. Defaults to true.
-
-offset=int Start io at the given offset in the file. The data before
- the given offset will not be touched. This effectively
- caps the file size at real_size - offset.
-
-offset_increment=int If this is provided, then the real offset becomes
- offset + offset_increment * thread_number, where the thread
- number is a counter that starts at 0 and is incremented for
- each sub-job (i.e. when numjobs option is specified). This
- option is useful if there are several jobs which are intended
- to operate on a file in parallel disjoint segments, with
- even spacing between the starting points.
-
-number_ios=int Fio will normally perform IOs until it has exhausted the size
- of the region set by size=, or if it exhaust the allocated
- time (or hits an error condition). With this setting, the
- range/size can be set independently of the number of IOs to
- perform. When fio reaches this number, it will exit normally
- and report status. Note that this does not extend the amount
- of IO that will be done, it will only stop fio if this
- condition is met before other end-of-job criteria.
-
-fsync=int If writing to a file, issue a sync of the dirty data
- for every number of blocks given. For example, if you give
- 32 as a parameter, fio will sync the file for every 32
- writes issued. If fio is using non-buffered io, we may
- not sync the file. The exception is the sg io engine, which
- synchronizes the disk cache anyway.
-
-fdatasync=int Like fsync= but uses fdatasync() to only sync data and not
- metadata blocks.
- In FreeBSD and Windows there is no fdatasync(), this falls back
- to using fsync()
-
-sync_file_range=str:val Use sync_file_range() for every 'val' number of
- write operations. Fio will track range of writes that
- have happened since the last sync_file_range() call. 'str'
- can currently be one or more of:
-
- wait_before SYNC_FILE_RANGE_WAIT_BEFORE
- write SYNC_FILE_RANGE_WRITE
- wait_after SYNC_FILE_RANGE_WAIT_AFTER
-
- So if you do sync_file_range=wait_before,write:8, fio would
- use SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE for
- every 8 writes. Also see the sync_file_range(2) man page.
- This option is Linux specific.
-
-overwrite=bool If true, writes to a file will always overwrite existing
- data. If the file doesn't already exist, it will be
- created before the write phase begins. If the file exists
- and is large enough for the specified write phase, nothing
- will be done.
-
-end_fsync=bool If true, fsync file contents when a write stage has completed.
-
-fsync_on_close=bool If true, fio will fsync() a dirty file on close.
- This differs from end_fsync in that it will happen on every
- file close, not just at the end of the job.
-
-rwmixread=int How large a percentage of the mix should be reads.
-
-rwmixwrite=int How large a percentage of the mix should be writes. If both
- rwmixread and rwmixwrite is given and the values do not add
- up to 100%, the latter of the two will be used to override
- the first. This may interfere with a given rate setting,
- if fio is asked to limit reads or writes to a certain rate.
- If that is the case, then the distribution may be skewed.
-
-random_distribution=str:float[,str:float][,str:float]
- By default, fio will use a completely uniform
- random distribution when asked to perform random IO. Sometimes
- it is useful to skew the distribution in specific ways,
- ensuring that some parts of the data is more hot than others.
- fio includes the following distribution models:
-
- random Uniform random distribution
- zipf Zipf distribution
- pareto Pareto distribution
- gauss Normal (gaussian) distribution
- zoned Zoned random distribution
-
- When using a zipf or pareto distribution, an input value
- is also needed to define the access pattern. For zipf, this
- is the zipf theta. For pareto, it's the pareto power. Fio
- includes a test program, genzipf, that can be used visualize
- what the given input values will yield in terms of hit rates.
- If you wanted to use zipf with a theta of 1.2, you would use
- random_distribution=zipf:1.2 as the option. If a non-uniform
- model is used, fio will disable use of the random map. For
- the gauss distribution, a normal deviation is supplied as
- a value between 0 and 100.
-
- For a zoned distribution, fio supports specifying percentages
- of IO access that should fall within what range of the file or
- device. For example, given a criteria of:
-
- 60% of accesses should be to the first 10%
- 30% of accesses should be to the next 20%
- 8% of accesses should be to to the next 30%
- 2% of accesses should be to the next 40%
-
- we can define that through zoning of the random accesses. For
- the above example, the user would do:
-
- random_distribution=zoned:60/10:30/20:8/30:2/40
-
- similarly to how bssplit works for setting ranges and
- percentages of block sizes. Like bssplit, it's possible to
- specify separate zones for reads, writes, and trims. If just
- one set is given, it'll apply to all of them.
-
-percentage_random=int[,int][,int]
- For a random workload, set how big a percentage should
- be random. This defaults to 100%, in which case the workload
- is fully random. It can be set from anywhere from 0 to 100.
- Setting it to 0 would make the workload fully sequential. Any
- setting in between will result in a random mix of sequential
- and random IO, at the given percentages.
- Comma-separated values may be specified for reads, writes,
- and trims as described in 'blocksize'.
-
-norandommap Normally fio will cover every block of the file when doing
- random IO. If this option is given, fio will just get a
- new random offset without looking at past io history. This
- means that some blocks may not be read or written, and that
- some blocks may be read/written more than once. If this option
- is used with verify= and multiple blocksizes (via bsrange=),
- only intact blocks are verified, i.e., partially-overwritten
- blocks are ignored.
-
-softrandommap=bool See norandommap. If fio runs with the random block map
- enabled and it fails to allocate the map, if this option is
- set it will continue without a random block map. As coverage
- will not be as complete as with random maps, this option is
- disabled by default.
-
-random_generator=str Fio supports the following engines for generating
- IO offsets for random IO:
-
- tausworthe Strong 2^88 cycle random number generator
- lfsr Linear feedback shift register generator
- tausworthe64 Strong 64-bit 2^258 cycle random number
- generator
-
- Tausworthe is a strong random number generator, but it
- requires tracking on the side if we want to ensure that
- blocks are only read or written once. LFSR guarantees
- that we never generate the same offset twice, and it's
- also less computationally expensive. It's not a true
- random generator, however, though for IO purposes it's
- typically good enough. LFSR only works with single
- block sizes, not with workloads that use multiple block
- sizes. If used with such a workload, fio may read or write
- some blocks multiple times. The default value is tausworthe,
- unless the required space exceeds 2^32 blocks. If it does,
- then tausworthe64 is selected automatically.
-
-nice=int Run the job with the given nice value. See man nice(2).
-
- On Windows, values less than -15 set the process class to "High";
- -1 through -15 set "Above Normal"; 1 through 15 "Below Normal";
- and above 15 "Idle" priority class.
-
-prio=int Set the io priority value of this job. Linux limits us to
- a positive value between 0 and 7, with 0 being the highest.
- See man ionice(1). Refer to an appropriate manpage for
- other operating systems since meaning of priority may differ.
-
-prioclass=int Set the io priority class. See man ionice(1).
-
-thinktime=int Stall the job x microseconds after an io has completed before
- issuing the next. May be used to simulate processing being
- done by an application. See thinktime_blocks and
- thinktime_spin.
-
-thinktime_spin=int
- Only valid if thinktime is set - pretend to spend CPU time
- doing something with the data received, before falling back
- to sleeping for the rest of the period specified by
- thinktime.
-
-thinktime_blocks=int
- Only valid if thinktime is set - control how many blocks
- to issue, before waiting 'thinktime' usecs. If not set,
- defaults to 1 which will make fio wait 'thinktime' usecs
- after every block. This effectively makes any queue depth
- setting redundant, since no more than 1 IO will be queued
- before we have to complete it and do our thinktime. In
- other words, this setting effectively caps the queue depth
- if the latter is larger.
-
-rate=int[,int][,int]
- Cap the bandwidth used by this job. The number is in bytes/sec,
- the normal suffix rules apply.
- Comma-separated values may be specified for reads, writes,
- and trims as described in 'blocksize'.
-
-rate_min=int[,int][,int]
- Tell fio to do whatever it can to maintain at least this
- bandwidth. Failing to meet this requirement will cause
- the job to exit.
- Comma-separated values may be specified for reads, writes,
- and trims as described in 'blocksize'.
-
-rate_iops=int[,int][,int]
- Cap the bandwidth to this number of IOPS. Basically the same
- as rate, just specified independently of bandwidth. If the
- job is given a block size range instead of a fixed value,
- the smallest block size is used as the metric.
- Comma-separated values may be specified for reads, writes,
- and trims as described in 'blocksize'.
-
-rate_iops_min=int[,int][,int]
- If fio doesn't meet this rate of IO, it will cause
- the job to exit.
- Comma-separated values may be specified for reads, writes,
- and trims as described in 'blocksize'.
-
-rate_process=str This option controls how fio manages rated IO
- submissions. The default is 'linear', which submits IO in a
- linear fashion with fixed delays between IOs that gets
- adjusted based on IO completion rates. If this is set to
- 'poisson', fio will submit IO based on a more real world
- random request flow, known as the Poisson process
- (https://en.wikipedia.org/wiki/Poisson_process). The lambda
- will be 10^6 / IOPS for the given workload.
-
-latency_target=int If set, fio will attempt to find the max performance
- point that the given workload will run at while maintaining a
- latency below this target. The values is given in microseconds.
- See latency_window and latency_percentile
-
-latency_window=int Used with latency_target to specify the sample window
- that the job is run at varying queue depths to test the
- performance. The value is given in microseconds.
-
-latency_percentile=float The percentage of IOs that must fall within the
- criteria specified by latency_target and latency_window. If not
- set, this defaults to 100.0, meaning that all IOs must be equal
- or below to the value set by latency_target.
-
-max_latency=int If set, fio will exit the job if it exceeds this maximum
- latency. It will exit with an ETIME error.
-
-rate_cycle=int Average bandwidth for 'rate' and 'rate_min' over this number
- of milliseconds.
-
-cpumask=int Set the CPU affinity of this job. The parameter given is a
- bitmask of allowed CPU's the job may run on. So if you want
- the allowed CPUs to be 1 and 5, you would pass the decimal
- value of (1 << 1 | 1 << 5), or 34. See man
- sched_setaffinity(2). This may not work on all supported
- operating systems or kernel versions. This option doesn't
- work well for a higher CPU count than what you can store in
- an integer mask, so it can only control cpus 1-32. For
- boxes with larger CPU counts, use cpus_allowed.
-
-cpus_allowed=str Controls the same options as cpumask, but it allows a text
- setting of the permitted CPUs instead. So to use CPUs 1 and
- 5, you would specify cpus_allowed=1,5. This options also
- allows a range of CPUs. Say you wanted a binding to CPUs
- 1, 5, and 8-15, you would set cpus_allowed=1,5,8-15.
-
-cpus_allowed_policy=str Set the policy of how fio distributes the CPUs
- specified by cpus_allowed or cpumask. Two policies are
- supported:
-
- shared All jobs will share the CPU set specified.
- split Each job will get a unique CPU from the CPU set.
-
- 'shared' is the default behaviour, if the option isn't
- specified. If split is specified, then fio will will assign
- one cpu per job. If not enough CPUs are given for the jobs
- listed, then fio will roundrobin the CPUs in the set.
-
-numa_cpu_nodes=str Set this job running on specified NUMA nodes' CPUs. The
- arguments allow comma delimited list of cpu numbers,
- A-B ranges, or 'all'. Note, to enable numa options support,
- fio must be built on a system with libnuma-dev(el) installed.
-
-numa_mem_policy=str Set this job's memory policy and corresponding NUMA
- nodes. Format of the arguments:
- <mode>[:<nodelist>]
- `mode' is one of the following memory policy:
- default, prefer, bind, interleave, local
- For `default' and `local' memory policy, no node is
- needed to be specified.
- For `prefer', only one node is allowed.
- For `bind' and `interleave', it allow comma delimited
- list of numbers, A-B ranges, or 'all'.
-
-startdelay=time Start this job the specified number of seconds after fio
- has started. Only useful if the job file contains several
- jobs, and you want to delay starting some jobs to a certain
- time.
-
-runtime=time Tell fio to terminate processing after the specified number
- of seconds. It can be quite hard to determine for how long
- a specified job will run, so this parameter is handy to
- cap the total runtime to a given time.
-
-time_based If set, fio will run for the duration of the runtime
- specified even if the file(s) are completely read or
- written. It will simply loop over the same workload
- as many times as the runtime allows.
-
-ramp_time=time If set, fio will run the specified workload for this amount
- of time before logging any performance numbers. Useful for
- letting performance settle before logging results, thus
- minimizing the runtime required for stable results. Note
- that the ramp_time is considered lead in time for a job,
- thus it will increase the total runtime if a special timeout
- or runtime is specified.
-
-steadystate=str:float
-ss=str:float Define the criterion and limit for assessing steady state
- performance. The first parameter designates the criterion
- whereas the second parameter sets the threshold. When the
- criterion falls below the threshold for the specified duration,
- the job will stop. For example, iops_slope:0.1% will direct fio
- to terminate the job when the least squares regression slope
- falls below 0.1% of the mean IOPS. If group_reporting is
- enabled this will apply to all jobs in the group. Below is the
- list of available steady state assessment criteria. All
- assessments are carried out using only data from the rolling
- collection window. Threshold limits can be expressed as a fixed
- value or as a percentage of the mean in the collection window.
- iops Collect IOPS data. Stop the job if all
- individual IOPS measurements are within the
- specified limit of the mean IOPS (e.g., iops:2
- means that all individual IOPS values must be
- within 2 of the mean, whereas iops:0.2% means
- that all individual IOPS values must be within
- 0.2% of the mean IOPS to terminate the job).
- iops_slope
- Collect IOPS data and calculate the least
- squares regression slope. Stop the job if the
- slope falls below the specified limit.
- bw Collect bandwidth data. Stop the job if all
- individual bandwidth measurements are within
- the specified limit of the mean bandwidth.
- bw_slope
- Collect bandwidth data and calculate the least
- squares regression slope. Stop the job if the
- slope falls below the specified limit.
-
-steadystate_duration=time
-ss_dur=time A rolling window of this duration will be used to judge whether
- steady state has been reached. Data will be collected once per
- second. The default is 0 which disables steady state detection.
-
-steadystate_ramp_time=time
-ss_ramp=time Allow the job to run for the specified duration before
- beginning data collection for checking the steady state job
- termination criterion. The default is 0.
-
-invalidate=bool Invalidate the buffer/page cache parts for this file prior
- to starting io. Defaults to true.
-
-sync=bool Use sync io for buffered writes. For the majority of the
- io engines, this means using O_SYNC.
-
-iomem=str
-mem=str Fio can use various types of memory as the I/O unit buffer.
- The allowed values are:
-
- malloc Use memory from malloc(3) as the buffers.
- Default memory type.
-
- shm Use shared memory as the buffers. Allocated
- through shmget(2).
-
- shmhuge Same as shm, but use huge pages as backing.
-
- mmap Use mmap to allocate buffers. May either be
- anonymous memory, or can be file backed if
- a filename is given after the option. The
- format is mem=mmap:/path/to/file.
-
- mmaphuge Use a memory mapped huge file as the buffer
- backing. Append filename after mmaphuge, ala
- mem=mmaphuge:/hugetlbfs/file
-
- mmapshared Same as mmap, but use a MMAP_SHARED
- mapping.
-
- The area allocated is a function of the maximum allowed
- bs size for the job, multiplied by the io depth given. Note
- that for shmhuge and mmaphuge to work, the system must have
- free huge pages allocated. This can normally be checked
- and set by reading/writing /proc/sys/vm/nr_hugepages on a
- Linux system. Fio assumes a huge page is 4MiB in size. So
- to calculate the number of huge pages you need for a given
- job file, add up the io depth of all jobs (normally one unless
- iodepth= is used) and multiply by the maximum bs set. Then
- divide that number by the huge page size. You can see the
- size of the huge pages in /proc/meminfo. If no huge pages
- are allocated by having a non-zero number in nr_hugepages,
- using mmaphuge or shmhuge will fail. Also see hugepage-size.
-
- mmaphuge also needs to have hugetlbfs mounted and the file
- location should point there. So if it's mounted in /huge,
- you would use mem=mmaphuge:/huge/somefile.
-
-iomem_align=int This indicates the memory alignment of the IO memory buffers.
- Note that the given alignment is applied to the first I/O unit
- buffer, if using iodepth the alignment of the following buffers
- are given by the bs used. In other words, if using a bs that is
- a multiple of the page sized in the system, all buffers will
- be aligned to this value. If using a bs that is not page
- aligned, the alignment of subsequent IO memory buffers is the
- sum of the iomem_align and bs used.
-
-hugepage-size=int
- Defines the size of a huge page. Must at least be equal
- to the system setting, see /proc/meminfo. Defaults to 4MiB.
- Should probably always be a multiple of megabytes, so using
- hugepage-size=Xm is the preferred way to set this to avoid
- setting a non-pow-2 bad value.
-
-exitall When one job finishes, terminate the rest. The default is
- to wait for each job to finish, sometimes that is not the
- desired action.
-
-exitall_on_error When one job finishes in error, terminate the rest. The
- default is to wait for each job to finish.
-
-bwavgtime=int Average the calculated bandwidth over the given time. Value
- is specified in milliseconds. If the job also does bandwidth
- logging through 'write_bw_log', then the minimum of this option
- and 'log_avg_msec' will be used. Default: 500ms.
-
-iopsavgtime=int Average the calculated IOPS over the given time. Value
- is specified in milliseconds. If the job also does IOPS logging
- through 'write_iops_log', then the minimum of this option and
- 'log_avg_msec' will be used. Default: 500ms.
-
-create_serialize=bool If true, serialize the file creation for the jobs.
- This may be handy to avoid interleaving of data
- files, which may greatly depend on the filesystem
- used and even the number of processors in the system.
-
-create_fsync=bool fsync the data file after creation. This is the
- default.
-
-create_on_open=bool Don't pre-setup the files for IO, just create open()
- when it's time to do IO to that file.
-
-create_only=bool If true, fio will only run the setup phase of the job.
- If files need to be laid out or updated on disk, only
- that will be done. The actual job contents are not
- executed.
-
-allow_file_create=bool If true, fio is permitted to create files as part
- of its workload. This is the default behavior. If this
- option is false, then fio will error out if the files it
- needs to use don't already exist. Default: true.
-
-allow_mounted_write=bool If this isn't set, fio will abort jobs that
- are destructive (eg that write) to what appears to be a
- mounted device or partition. This should help catch creating
- inadvertently destructive tests, not realizing that the test
- will destroy data on the mounted file system. Default: false.
-
-pre_read=bool If this is given, files will be pre-read into memory before
- starting the given IO operation. This will also clear
- the 'invalidate' flag, since it is pointless to pre-read
- and then drop the cache. This will only work for IO engines
- that are seek-able, since they allow you to read the same data
- multiple times. Thus it will not work on eg network or splice
- IO.
-
-unlink=bool Unlink the job files when done. Not the default, as repeated
- runs of that job would then waste time recreating the file
- set again and again.
-
-unlink_each_loop=bool Unlink job files after each iteration or loop.
-
-loops=int Run the specified number of iterations of this job. Used
- to repeat the same workload a given number of times. Defaults
- to 1.
-
-verify_only Do not perform specified workload---only verify data still
- matches previous invocation of this workload. This option
- allows one to check data multiple times at a later date
- without overwriting it. This option makes sense only for
- workloads that write data, and does not support workloads
- with the time_based option set.
-
-do_verify=bool Run the verify phase after a write phase. Only makes sense if
- verify is set. Defaults to 1.
-
-verify=str If writing to a file, fio can verify the file contents
- after each iteration of the job. Each verification method also implies
- verification of special header, which is written to the beginning of
- each block. This header also includes meta information, like offset
- of the block, block number, timestamp when block was written, etc.
- verify=str can be combined with verify_pattern=str option.
- The allowed values are:
-
- md5 Use an md5 sum of the data area and store
- it in the header of each block.
-
- crc64 Use an experimental crc64 sum of the data
- area and store it in the header of each
- block.
-
- crc32c Use a crc32c sum of the data area and store
- it in the header of each block.
-
- crc32c-intel Use hardware assisted crc32c calculation
- provided on SSE4.2 enabled processors. Falls
- back to regular software crc32c, if not
- supported by the system.
-
- crc32c-arm64 Use hardware assisted crc32c calculation
- provided on CRC enabled ARM 64-bits processors.
- Falls back to regular software crc32c, if not
- supported by the system.
-
- crc32 Use a crc32 sum of the data area and store
- it in the header of each block.
-
- crc16 Use a crc16 sum of the data area and store
- it in the header of each block.
-
- crc7 Use a crc7 sum of the data area and store
- it in the header of each block.
-
- xxhash Use xxhash as the checksum function. Generally
- the fastest software checksum that fio
- supports.
-
- sha512 Use sha512 as the checksum function.
-
- sha256 Use sha256 as the checksum function.
-
- sha1 Use optimized sha1 as the checksum function.
-
- meta This option is deprecated, since now meta information is
- included in generic verification header and meta verification
- happens by default. For detailed information see the description
- of the verify=str setting. This option is kept because of
- compatibility's sake with old configurations. Do not use it.
-
- pattern Verify a strict pattern. Normally fio includes
- a header with some basic information and
- checksumming, but if this option is set, only
- the specific pattern set with 'verify_pattern'
- is verified.
-
- null Only pretend to verify. Useful for testing
- internals with ioengine=null, not for much
- else.
-
- This option can be used for repeated burn-in tests of a
- system to make sure that the written data is also
- correctly read back. If the data direction given is
- a read or random read, fio will assume that it should
- verify a previously written file. If the data direction
- includes any form of write, the verify will be of the
- newly written data.
-
-verifysort=bool If set, fio will sort written verify blocks when it deems
- it faster to read them back in a sorted manner. This is
- often the case when overwriting an existing file, since
- the blocks are already laid out in the file system. You
- can ignore this option unless doing huge amounts of really
- fast IO where the red-black tree sorting CPU time becomes
- significant.
-
-verify_offset=int Swap the verification header with data somewhere else
- in the block before writing. Its swapped back before
- verifying.
-
-verify_interval=int Write the verification header at a finer granularity
- than the blocksize. It will be written for chunks the
- size of header_interval. blocksize should divide this
- evenly.
-
-verify_pattern=str If set, fio will fill the io buffers with this
- pattern. Fio defaults to filling with totally random
- bytes, but sometimes it's interesting to fill with a known
- pattern for io verification purposes. Depending on the
- width of the pattern, fio will fill 1/2/3/4 bytes of the
- buffer at the time(it can be either a decimal or a hex number).
- The verify_pattern if larger than a 32-bit quantity has to
- be a hex number that starts with either "0x" or "0X". Use
- with verify=str. Also, verify_pattern supports %o format,
- which means that for each block offset will be written and
- then verified back, e.g.:
+Job description
+~~~~~~~~~~~~~~~
- verify_pattern=%o
+.. option:: name=str
- Or use combination of everything:
- verify_pattern=0xff%o"abcd"-12
+ ASCII name of the job. This may be used to override the name printed by fio
+ for this job. Otherwise the job name is used. On the command line this
+ parameter has the special purpose of also signaling the start of a new job.
-verify_fatal=bool Normally fio will keep checking the entire contents
- before quitting on a block verification failure. If this
- option is set, fio will exit the job on the first observed
- failure.
-
-verify_dump=bool If set, dump the contents of both the original data
- block and the data block we read off disk to files. This
- allows later analysis to inspect just what kind of data
- corruption occurred. Off by default.
-
-verify_async=int Fio will normally verify IO inline from the submitting
- thread. This option takes an integer describing how many
- async offload threads to create for IO verification instead,
- causing fio to offload the duty of verifying IO contents
- to one or more separate threads. If using this offload
- option, even sync IO engines can benefit from using an
- iodepth setting higher than 1, as it allows them to have
- IO in flight while verifies are running.
-
-verify_async_cpus=str Tell fio to set the given CPU affinity on the
- async IO verification threads. See cpus_allowed for the
- format used.
-
-verify_backlog=int Fio will normally verify the written contents of a
- job that utilizes verify once that job has completed. In
- other words, everything is written then everything is read
- back and verified. You may want to verify continually
- instead for a variety of reasons. Fio stores the meta data
- associated with an IO block in memory, so for large
- verify workloads, quite a bit of memory would be used up
- holding this meta data. If this option is enabled, fio
- will write only N blocks before verifying these blocks.
-
-verify_backlog_batch=int Control how many blocks fio will verify
- if verify_backlog is set. If not set, will default to
- the value of verify_backlog (meaning the entire queue
- is read back and verified). If verify_backlog_batch is
- less than verify_backlog then not all blocks will be verified,
- if verify_backlog_batch is larger than verify_backlog, some
- blocks will be verified more than once.
-
-verify_state_save=bool When a job exits during the write phase of a verify
- workload, save its current state. This allows fio to replay
- up until that point, if the verify state is loaded for the
- verify read phase. The format of the filename is, roughly,
- <type>-<jobname>-<jobindex>-verify.state. <type> is "local"
- for a local run, "sock" for a client/server socket connection,
- and "ip" (192.168.0.1, for instance) for a networked
- client/server connection.
-
-verify_state_load=bool If a verify termination trigger was used, fio stores
- the current write state of each thread. This can be used at
- verification time so that fio knows how far it should verify.
- Without this information, fio will run a full verification
- pass, according to the settings in the job file used.
-
-stonewall
-wait_for_previous Wait for preceding jobs in the job file to exit, before
- starting this one. Can be used to insert serialization
- points in the job file. A stone wall also implies starting
- a new reporting group.
-
-new_group Start a new reporting group. See: group_reporting.
-
-numjobs=int Create the specified number of clones of this job. May be
- used to setup a larger number of threads/processes doing
- the same thing. Each thread is reported separately; to see
- statistics for all clones as a whole, use group_reporting in
- conjunction with new_group.
-
-group_reporting It may sometimes be interesting to display statistics for
- groups of jobs as a whole instead of for each individual job.
- This is especially true if 'numjobs' is used; looking at
- individual thread/process output quickly becomes unwieldy.
- To see the final report per-group instead of per-job, use
- 'group_reporting'. Jobs in a file will be part of the same
- reporting group, unless if separated by a stonewall, or by
- using 'new_group'.
-
-thread fio defaults to forking jobs, however if this option is
- given, fio will use pthread_create(3) to create threads
- instead.
-
-zonesize=int Divide a file into zones of the specified size. See zoneskip.
-
-zoneskip=int Skip the specified number of bytes when zonesize data has
- been read. The two zone options can be used to only do
- io on zones of a file.
-
-write_iolog=str Write the issued io patterns to the specified file. See
- read_iolog. Specify a separate file for each job, otherwise
- the iologs will be interspersed and the file may be corrupt.
-
-read_iolog=str Open an iolog with the specified file name and replay the
- io patterns it contains. This can be used to store a
- workload and replay it sometime later. The iolog given
- may also be a blktrace binary file, which allows fio
- to replay a workload captured by blktrace. See blktrace
- for how to capture such logging data. For blktrace replay,
- the file needs to be turned into a blkparse binary data
- file first (blkparse <device> -o /dev/null -d file_for_fio.bin).
-
-replay_no_stall=int When replaying I/O with read_iolog the default behavior
- is to attempt to respect the time stamps within the log and
- replay them with the appropriate delay between IOPS. By
- setting this variable fio will not respect the timestamps and
- attempt to replay them as fast as possible while still
- respecting ordering. The result is the same I/O pattern to a
- given device, but different timings.
-
-replay_redirect=str While replaying I/O patterns using read_iolog the
- default behavior is to replay the IOPS onto the major/minor
- device that each IOP was recorded from. This is sometimes
- undesirable because on a different machine those major/minor
- numbers can map to a different device. Changing hardware on
- the same system can also result in a different major/minor
- mapping. Replay_redirect causes all IOPS to be replayed onto
- the single specified device regardless of the device it was
- recorded from. i.e. replay_redirect=/dev/sdc would cause all
- IO in the blktrace or iolog to be replayed onto /dev/sdc.
- This means multiple devices will be replayed onto a single
- device, if the trace contains multiple devices. If you want
- multiple devices to be replayed concurrently to multiple
- redirected devices you must blkparse your trace into separate
- traces and replay them with independent fio invocations.
- Unfortunately this also breaks the strict time ordering
- between multiple device accesses.
-
-replay_align=int Force alignment of IO offsets and lengths in a trace
- to this power of 2 value.
-
-replay_scale=int Scale sector offsets down by this factor when
- replaying traces.
-
-per_job_logs=bool If set, this generates bw/clat/iops log with per
- file private filenames. If not set, jobs with identical names
- will share the log filename. Default: true.
-
-write_bw_log=str If given, write a bandwidth log of the jobs in this job
- file. Can be used to store data of the bandwidth of the
- jobs in their lifetime. The included fio_generate_plots
- script uses gnuplot to turn these text files into nice
- graphs. See write_lat_log for behaviour of given
- filename. For this option, the suffix is _bw.x.log, where
- x is the index of the job (1..N, where N is the number of
- jobs). If 'per_job_logs' is false, then the filename will not
- include the job index. See 'Log File Formats'.
-
-write_lat_log=str Same as write_bw_log, except that this option stores io
- submission, completion, and total latencies instead. If no
- filename is given with this option, the default filename of
- "jobname_type.log" is used. Even if the filename is given,
- fio will still append the type of log. So if one specifies
+.. option:: description=str
- write_lat_log=foo
+ Text description of the job. Doesn't do anything except dump this text
+ description when this job is run. It's not parsed.
- The actual log names will be foo_slat.x.log, foo_clat.x.log,
- and foo_lat.x.log, where x is the index of the job (1..N,
- where N is the number of jobs). This helps fio_generate_plot
- find the logs automatically. If 'per_job_logs' is false, then
- the filename will not include the job index. See 'Log File
- Formats'.
-
-write_hist_log=str Same as write_lat_log, but writes I/O completion
- latency histograms. If no filename is given with this option, the
- default filename of "jobname_clat_hist.x.log" is used, where x is
- the index of the job (1..N, where N is the number of jobs). Even
- if the filename is given, fio will still append the type of log.
- If per_job_logs is false, then the filename will not include the
- job index. See 'Log File Formats'.
-
-write_iops_log=str Same as write_bw_log, but writes IOPS. If no filename is
- given with this option, the default filename of
- "jobname_type.x.log" is used,where x is the index of the job
- (1..N, where N is the number of jobs). Even if the filename
- is given, fio will still append the type of log. If
- 'per_job_logs' is false, then the filename will not include
- the job index. See 'Log File Formats'.
-
-log_avg_msec=int By default, fio will log an entry in the iops, latency,
- or bw log for every IO that completes. When writing to the
- disk log, that can quickly grow to a very large size. Setting
- this option makes fio average the each log entry over the
- specified period of time, reducing the resolution of the log.
- See log_max_value as well. Defaults to 0, logging all entries.
-
-log_hist_msec=int Same as log_avg_msec, but logs entries for completion
- latency histograms. Computing latency percentiles from averages of
- intervals using log_avg_msec is innacurate. Setting this option makes
- fio log histogram entries over the specified period of time, reducing
- log sizes for high IOPS devices while retaining percentile accuracy.
- See log_hist_coarseness as well. Defaults to 0, meaning histogram
- logging is disabled.
-
-log_hist_coarseness=int Integer ranging from 0 to 6, defining the coarseness
- of the resolution of the histogram logs enabled with log_hist_msec. For
- each increment in coarseness, fio outputs half as many bins. Defaults to
- 0, for which histogram logs contain 1216 latency bins. See
- 'Log File Formats'.
-
-log_max_value=bool If log_avg_msec is set, fio logs the average over that
- window. If you instead want to log the maximum value, set this
- option to 1. Defaults to 0, meaning that averaged values are
- logged.
-
-log_offset=int If this is set, the iolog options will include the byte
- offset for the IO entry as well as the other data values.
-
-log_compression=int If this is set, fio will compress the IO logs as
- it goes, to keep the memory footprint lower. When a log
- reaches the specified size, that chunk is removed and
- compressed in the background. Given that IO logs are
- fairly highly compressible, this yields a nice memory
- savings for longer runs. The downside is that the
- compression will consume some background CPU cycles, so
- it may impact the run. This, however, is also true if
- the logging ends up consuming most of the system memory.
- So pick your poison. The IO logs are saved normally at the
- end of a run, by decompressing the chunks and storing them
- in the specified log file. This feature depends on the
- availability of zlib.
-
-log_compression_cpus=str Define the set of CPUs that are allowed to
- handle online log compression for the IO jobs. This can
- provide better isolation between performance sensitive jobs,
- and background compression work.
-
-log_store_compressed=bool If set, fio will store the log files in a
- compressed format. They can be decompressed with fio, using
- the --inflate-log command line parameter. The files will be
- stored with a .fz suffix.
-
-log_unix_epoch=bool If set, fio will log Unix timestamps to the log
- files produced by enabling write_type_log for each log type, instead
- of the default zero-based timestamps.
-
-block_error_percentiles=bool If set, record errors in trim block-sized
- units from writes and trims and output a histogram of
- how many trims it took to get to errors, and what kind
- of error was encountered.
-
-lockmem=int Pin down the specified amount of memory with mlock(2). Can
- potentially be used instead of removing memory or booting
- with less memory to simulate a smaller amount of memory.
- The amount specified is per worker.
-
-exec_prerun=str Before running this job, issue the command specified
- through system(3). Output is redirected in a file called
- jobname.prerun.txt.
-
-exec_postrun=str After the job completes, issue the command specified
- though system(3). Output is redirected in a file called
- jobname.postrun.txt.
-
-ioscheduler=str Attempt to switch the device hosting the file to the specified
- io scheduler before running.
-
-disk_util=bool Generate disk utilization statistics, if the platform
- supports it. Defaults to on.
-
-disable_lat=bool Disable measurements of total latency numbers. Useful
- only for cutting back the number of calls to gettimeofday,
- as that does impact performance at really high IOPS rates.
- Note that to really get rid of a large amount of these
- calls, this option must be used with disable_slat and
- disable_bw as well.
-
-disable_clat=bool Disable measurements of completion latency numbers. See
- disable_lat.
-
-disable_slat=bool Disable measurements of submission latency numbers. See
- disable_slat.
-
-disable_bw=bool Disable measurements of throughput/bandwidth numbers. See
- disable_lat.
-
-clat_percentiles=bool Enable the reporting of percentiles of
- completion latencies.
-
-percentile_list=float_list Overwrite the default list of percentiles
- for completion latencies and the block error histogram.
- Each number is a floating number in the range (0,100],
- and the maximum length of the list is 20. Use ':'
- to separate the numbers, and list the numbers in ascending
- order. For example, --percentile_list=99.5:99.9 will cause
- fio to report the values of completion latency below which
- 99.5% and 99.9% of the observed latencies fell, respectively.
-
-clocksource=str Use the given clocksource as the base of timing. The
- supported options are:
-
- gettimeofday gettimeofday(2)
-
- clock_gettime clock_gettime(2)
-
- cpu Internal CPU clock source
-
- cpu is the preferred clocksource if it is reliable, as it
- is very fast (and fio is heavy on time calls). Fio will
- automatically use this clocksource if it's supported and
- considered reliable on the system it is running on, unless
- another clocksource is specifically set. For x86/x86-64 CPUs,
- this means supporting TSC Invariant.
-
-gtod_reduce=bool Enable all of the gettimeofday() reducing options
- (disable_clat, disable_slat, disable_bw) plus reduce
- precision of the timeout somewhat to really shrink
- the gettimeofday() call count. With this option enabled,
- we only do about 0.4% of the gtod() calls we would have
- done if all time keeping was enabled.
-
-gtod_cpu=int Sometimes it's cheaper to dedicate a single thread of
- execution to just getting the current time. Fio (and
- databases, for instance) are very intensive on gettimeofday()
- calls. With this option, you can set one CPU aside for
- doing nothing but logging current time to a shared memory
- location. Then the other threads/processes that run IO
- workloads need only copy that segment, instead of entering
- the kernel with a gettimeofday() call. The CPU set aside
- for doing these time calls will be excluded from other
- uses. Fio will manually clear it from the CPU mask of other
- jobs.
-
-continue_on_error=str Normally fio will exit the job on the first observed
- failure. If this option is set, fio will continue the job when
- there is a 'non-fatal error' (EIO or EILSEQ) until the runtime
- is exceeded or the I/O size specified is completed. If this
- option is used, there are two more stats that are appended,
- the total error count and the first error. The error field
- given in the stats is the first error that was hit during the
- run.
+.. option:: loops=int
- The allowed values are:
+ Run the specified number of iterations of this job. Used to repeat the same
+ workload a given number of times. Defaults to 1.
- none Exit on any IO or verify errors.
+.. option:: numjobs=int
- read Continue on read errors, exit on all others.
+ Create the specified number of clones of this job. Each clone of job
+ is spawned as an independent thread or process. May be used to setup a
+ larger number of threads/processes doing the same thing. Each thread is
+ reported separately; to see statistics for all clones as a whole, use
+ :option:`group_reporting` in conjunction with :option:`new_group`.
+ See :option:`--max-jobs`. Default: 1.
- write Continue on write errors, exit on all others.
- io Continue on any IO error, exit on all others.
+Time related parameters
+~~~~~~~~~~~~~~~~~~~~~~~
- verify Continue on verify errors, exit on all others.
+.. option:: runtime=time
- all Continue on all errors.
+ Tell fio to terminate processing after the specified period of time. It
+ can be quite hard to determine for how long a specified job will run, so
+ this parameter is handy to cap the total runtime to a given time. When
+ the unit is omitted, the value is intepreted in seconds.
- 0 Backward-compatible alias for 'none'.
+.. option:: time_based
- 1 Backward-compatible alias for 'all'.
+ If set, fio will run for the duration of the :option:`runtime` specified
+ even if the file(s) are completely read or written. It will simply loop over
+ the same workload as many times as the :option:`runtime` allows.
-ignore_error=str Sometimes you want to ignore some errors during test
- in that case you can specify error list for each error type.
- ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST
- errors for given error type is separated with ':'. Error
- may be symbol ('ENOSPC', 'ENOMEM') or integer.
- Example:
- ignore_error=EAGAIN,ENOSPC:122
- This option will ignore EAGAIN from READ, and ENOSPC and
- 122(EDQUOT) from WRITE.
+.. option:: startdelay=irange(time)
-error_dump=bool If set dump every error even if it is non fatal, true
- by default. If disabled only fatal error will be dumped
+ Delay the start of job for the specified amount of time. Can be a single
+ value or a range. When given as a range, each thread will choose a value
+ randomly from within the range. Value is in seconds if a unit is omitted.
-cgroup=str Add job to this control group. If it doesn't exist, it will
- be created. The system must have a mounted cgroup blkio
- mount point for this to work. If your system doesn't have it
- mounted, you can do so with:
+.. option:: ramp_time=time
- # mount -t cgroup -o blkio none /cgroup
+ If set, fio will run the specified workload for this amount of time before
+ logging any performance numbers. Useful for letting performance settle
+ before logging results, thus minimizing the runtime required for stable
+ results. Note that the ``ramp_time`` is considered lead in time for a job,
+ thus it will increase the total runtime if a special timeout or
+ :option:`runtime` is specified. When the unit is omitted, the value is
+ given in seconds.
-cgroup_weight=int Set the weight of the cgroup to this value. See
- the documentation that comes with the kernel, allowed values
- are in the range of 100..1000.
+.. option:: clocksource=str
-cgroup_nodelete=bool Normally fio will delete the cgroups it has created after
- the job completion. To override this behavior and to leave
- cgroups around after the job completion, set cgroup_nodelete=1.
- This can be useful if one wants to inspect various cgroup
- files after job completion. Default: false
+ Use the given clocksource as the base of timing. The supported options are:
-uid=int Instead of running as the invoking user, set the user ID to
- this value before the thread/process does any work.
+ **gettimeofday**
+ :manpage:`gettimeofday(2)`
-gid=int Set group ID, see uid.
+ **clock_gettime**
+ :manpage:`clock_gettime(2)`
-flow_id=int The ID of the flow. If not specified, it defaults to being a
- global flow. See flow.
+ **cpu**
+ Internal CPU clock source
-flow=int Weight in token-based flow control. If this value is used, then
- there is a 'flow counter' which is used to regulate the
- proportion of activity between two or more jobs. fio attempts
- to keep this flow counter near zero. The 'flow' parameter
- stands for how much should be added or subtracted to the flow
- counter on each iteration of the main I/O loop. That is, if
- one job has flow=8 and another job has flow=-1, then there
- will be a roughly 1:8 ratio in how much one runs vs the other.
+ cpu is the preferred clocksource if it is reliable, as it is very fast (and
+ fio is heavy on time calls). Fio will automatically use this clocksource if
+ it's supported and considered reliable on the system it is running on,
+ unless another clocksource is specifically set. For x86/x86-64 CPUs, this
+ means supporting TSC Invariant.
-flow_watermark=int The maximum value that the absolute value of the flow
- counter is allowed to reach before the job must wait for a
- lower value of the counter.
+.. option:: gtod_reduce=bool
-flow_sleep=int The period of time, in microseconds, to wait after the flow
- watermark has been exceeded before retrying operations
+ Enable all of the :manpage:`gettimeofday(2)` reducing options
+ (:option:`disable_clat`, :option:`disable_slat`, :option:`disable_bw_measurement`) plus
+ reduce precision of the timeout somewhat to really shrink the
+ :manpage:`gettimeofday(2)` call count. With this option enabled, we only do
+ about 0.4% of the :manpage:`gettimeofday(2)` calls we would have done if all
+ time keeping was enabled.
-In addition, there are some parameters which are only valid when a specific
-ioengine is in use. These are used identically to normal parameters, with the
-caveat that when used on the command line, they must come after the ioengine
-that defines them is selected.
-
-[libaio] userspace_reap Normally, with the libaio engine in use, fio will use
- the io_getevents system call to reap newly returned events.
- With this flag turned on, the AIO ring will be read directly
- from user-space to reap events. The reaping mode is only
- enabled when polling for a minimum of 0 events (eg when
- iodepth_batch_complete=0).
-
-[psyncv2] hipri Set RWF_HIPRI on IO, indicating to the kernel that
- it's of higher priority than normal.
-
-[cpuio] cpuload=int Attempt to use the specified percentage of CPU cycles.
-
-[cpuio] cpuchunks=int Split the load into cycles of the given time. In
- microseconds.
-
-[cpuio] exit_on_io_done=bool Detect when IO threads are done, then exit.
-
-[netsplice] hostname=str
-[net] hostname=str The host name or IP address to use for TCP or UDP based IO.
- If the job is a TCP listener or UDP reader, the hostname is not
- used and must be omitted unless it is a valid UDP multicast
- address.
-[libhdfs] namenode=str The host name or IP address of a HDFS cluster namenode to contact.
-
-[netsplice] port=int
-[net] port=int The TCP or UDP port to bind to or connect to. If this is used
-with numjobs to spawn multiple instances of the same job type, then this will
-be the starting port number since fio will use a range of ports.
-[libhdfs] port=int the listening port of the HFDS cluster namenode.
-
-[netsplice] interface=str
-[net] interface=str The IP address of the network interface used to send or
- receive UDP multicast
-
-[netsplice] ttl=int
-[net] ttl=int Time-to-live value for outgoing UDP multicast packets.
- Default: 1
-
-[netsplice] nodelay=bool
-[net] nodelay=bool Set TCP_NODELAY on TCP connections.
-
-[netsplice] protocol=str
-[netsplice] proto=str
-[net] protocol=str
-[net] proto=str The network protocol to use. Accepted values are:
-
- tcp Transmission control protocol
- tcpv6 Transmission control protocol V6
- udp User datagram protocol
- udpv6 User datagram protocol V6
- unix UNIX domain socket
-
- When the protocol is TCP or UDP, the port must also be given,
- as well as the hostname if the job is a TCP listener or UDP
- reader. For unix sockets, the normal filename option should be
- used and the port is invalid.
-
-[net] listen For TCP network connections, tell fio to listen for incoming
- connections rather than initiating an outgoing connection. The
- hostname must be omitted if this option is used.
-
-[net] pingpong Normally a network writer will just continue writing data, and
- a network reader will just consume packages. If pingpong=1
- is set, a writer will send its normal payload to the reader,
- then wait for the reader to send the same payload back. This
- allows fio to measure network latencies. The submission
- and completion latencies then measure local time spent
- sending or receiving, and the completion latency measures
- how long it took for the other end to receive and send back.
- For UDP multicast traffic pingpong=1 should only be set for a
- single reader when multiple readers are listening to the same
- address.
-
-[net] window_size Set the desired socket buffer size for the connection.
-
-[net] mss Set the TCP maximum segment size (TCP_MAXSEG).
-
-[e4defrag] donorname=str
- File will be used as a block donor(swap extents between files)
-[e4defrag] inplace=int
- Configure donor file blocks allocation strategy
- 0(default): Preallocate donor's file on init
- 1 : allocate space immediately inside defragment event,
- and free right after event
-
-[rbd] clustername=str Specifies the name of the Ceph cluster.
-[rbd] rbdname=str Specifies the name of the RBD.
-[rbd] pool=str Specifies the name of the Ceph pool containing RBD.
-[rbd] clientname=str Specifies the username (without the 'client.' prefix)
- used to access the Ceph cluster. If the clustername is
- specified, the clientname shall be the full type.id
- string. If no type. prefix is given, fio will add
- 'client.' by default.
-
-[mtd] skip_bad=bool Skip operations against known bad blocks.
-
-[libhdfs] hdfsdirectory libhdfs will create chunk in this HDFS directory
-[libhdfs] chunk_size the size of the chunk to use for each file.
-
-
-6.0 Interpreting the output
----------------------------
-
-fio spits out a lot of output. While running, fio will display the
-status of the jobs created. An example of that would be:
-
-Jobs: 1: [_r] [24.8% done] [r=20992KiB/s,w=24064KiB/s,t=0KiB/s] [r=82,w=94,t=0 iops] [eta 00h:01m:31s]
-
-The characters inside the square brackets denote the current status of
-each thread. The possible values (in typical life cycle order) are:
-
-Idle Run
----- ---
-P Thread setup, but not started.
-C Thread created.
-I Thread initialized, waiting or generating necessary data.
- p Thread running pre-reading file(s).
- R Running, doing sequential reads.
- r Running, doing random reads.
- W Running, doing sequential writes.
- w Running, doing random writes.
- M Running, doing mixed sequential reads/writes.
- m Running, doing mixed random reads/writes.
- F Running, currently waiting for fsync()
- f Running, finishing up (writing IO logs, etc)
- V Running, doing verification of written data.
-E Thread exited, not reaped by main thread yet.
-_ Thread reaped, or
-X Thread reaped, exited with an error.
-K Thread reaped, exited due to signal.
-
-Fio will condense the thread string as not to take up more space on the
-command line as is needed. For instance, if you have 10 readers and 10
-writers running, the output would look like this:
-
-Jobs: 20 (f=20): [R(10),W(10)] [4.0% done] [r=20992KiB/s,w=24064KiB/s,t=0KiB/s] [r=82,w=94,t=0 iops] [eta 57m:36s]
-
-Fio will still maintain the ordering, though. So the above means that jobs
-1..10 are readers, and 11..20 are writers.
-
-The other values are fairly self explanatory - number of threads
-currently running and doing io, rate of io since last check (read speed
-listed first, then write speed), and the estimated completion percentage
-and time for the running group. It's impossible to estimate runtime of
-the following groups (if any). Note that the string is displayed in order,
-so it's possible to tell which of the jobs are currently doing what. The
-first character is the first job defined in the job file, and so forth.
-
-When fio is done (or interrupted by ctrl-c), it will show the data for
-each thread, group of threads, and disks in that order. For each data
-direction, the output looks like:
-
-Client1 (g=0): err= 0:
- write: io= 32MiB, bw= 666KiB/s, iops=89 , runt= 50320msec
- slat (msec): min= 0, max= 136, avg= 0.03, stdev= 1.92
- clat (msec): min= 0, max= 631, avg=48.50, stdev=86.82
- bw (KiB/s) : min= 0, max= 1196, per=51.00%, avg=664.02, stdev=681.68
- cpu : usr=1.49%, sys=0.25%, ctx=7969, majf=0, minf=17
- IO depths : 1=0.1%, 2=0.3%, 4=0.5%, 8=99.0%, 16=0.0%, 32=0.0%, >32=0.0%
- submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
- complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
- issued r/w: total=0/32768, short=0/0
- lat (msec): 2=1.6%, 4=0.0%, 10=3.2%, 20=12.8%, 50=38.4%, 100=24.8%,
- lat (msec): 250=15.2%, 500=0.0%, 750=0.0%, 1000=0.0%, >=2048=0.0%
-
-The client number is printed, along with the group id and error of that
-thread. Below is the io statistics, here for writes. In the order listed,
-they denote:
-
-io= Number of megabytes io performed
-bw= Average bandwidth rate
-iops= Average IOs performed per second
-runt= The runtime of that thread
- slat= Submission latency (avg being the average, stdev being the
- standard deviation). This is the time it took to submit
- the io. For sync io, the slat is really the completion
- latency, since queue/complete is one operation there. This
- value can be in milliseconds or microseconds, fio will choose
- the most appropriate base and print that. In the example
- above, milliseconds is the best scale. Note: in --minimal mode
- latencies are always expressed in microseconds.
- clat= Completion latency. Same names as slat, this denotes the
- time from submission to completion of the io pieces. For
- sync io, clat will usually be equal (or very close) to 0,
- as the time from submit to complete is basically just
- CPU time (io has already been done, see slat explanation).
- bw= Bandwidth. Same names as the xlat stats, but also includes
- an approximate percentage of total aggregate bandwidth
- this thread received in this group. This last value is
- only really useful if the threads in this group are on the
- same disk, since they are then competing for disk access.
-cpu= CPU usage. User and system time, along with the number
- of context switches this thread went through, usage of
- system and user time, and finally the number of major
- and minor page faults. The CPU utilization numbers are
- averages for the jobs in that reporting group, while the
- context and fault counters are summed.
-IO depths= The distribution of io depths over the job life time. The
- numbers are divided into powers of 2, so for example the
- 16= entries includes depths up to that value but higher
- than the previous entry. In other words, it covers the
- range from 16 to 31.
-IO submit= How many pieces of IO were submitting in a single submit
- call. Each entry denotes that amount and below, until
- the previous entry - eg, 8=100% mean that we submitted
- anywhere in between 5-8 ios per submit call.
-IO complete= Like the above submit number, but for completions instead.
-IO issued= The number of read/write requests issued, and how many
- of them were short.
-IO latencies= The distribution of IO completion latencies. This is the
- time from when IO leaves fio and when it gets completed.
- The numbers follow the same pattern as the IO depths,
- meaning that 2=1.6% means that 1.6% of the IO completed
- within 2 msecs, 20=12.8% means that 12.8% of the IO
- took more than 10 msecs, but less than (or equal to) 20 msecs.
+.. option:: gtod_cpu=int
-After each client has been listed, the group statistics are printed. They
-will look like this:
+ Sometimes it's cheaper to dedicate a single thread of execution to just
+ getting the current time. Fio (and databases, for instance) are very
+ intensive on :manpage:`gettimeofday(2)` calls. With this option, you can set
+ one CPU aside for doing nothing but logging current time to a shared memory
+ location. Then the other threads/processes that run I/O workloads need only
+ copy that segment, instead of entering the kernel with a
+ :manpage:`gettimeofday(2)` call. The CPU set aside for doing these time
+ calls will be excluded from other uses. Fio will manually clear it from the
+ CPU mask of other jobs.
-Run status group 0 (all jobs):
- READ: io=64MB, aggrb=22178, minb=11355, maxb=11814, mint=2840msec, maxt=2955msec
- WRITE: io=64MB, aggrb=1302, minb=666, maxb=669, mint=50093msec, maxt=50320msec
-For each data direction, it prints:
+Target file/device
+~~~~~~~~~~~~~~~~~~
-io= Number of megabytes io performed.
-aggrb= Aggregate bandwidth of threads in this group.
-minb= The minimum average bandwidth a thread saw.
-maxb= The maximum average bandwidth a thread saw.
-mint= The smallest runtime of the threads in that group.
-maxt= The longest runtime of the threads in that group.
+.. option:: directory=str
-And finally, the disk statistics are printed. They will look like this:
+ Prefix filenames with this directory. Used to place files in a different
+ location than :file:`./`. You can specify a number of directories by
+ separating the names with a ':' character. These directories will be
+ assigned equally distributed to job clones created by :option:`numjobs` as
+ long as they are using generated filenames. If specific `filename(s)` are
+ set fio will use the first listed directory, and thereby matching the
+ `filename` semantic which generates a file each clone if not specified, but
+ let all clones use the same if set.
-Disk stats (read/write):
- sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00%
+ See the :option:`filename` option for information on how to escape "``:``" and
+ "``\``" characters within the directory path itself.
-Each value is printed for both reads and writes, with reads first. The
-numbers denote:
+.. option:: filename=str
-ios= Number of ios performed by all groups.
-merge= Number of merges io the io scheduler.
-ticks= Number of ticks we kept the disk busy.
-io_queue= Total time spent in the disk queue.
-util= The disk utilization. A value of 100% means we kept the disk
- busy constantly, 50% would be a disk idling half of the time.
+ Fio normally makes up a `filename` based on the job name, thread number, and
+ file number (see :option:`filename_format`). If you want to share files
+ between threads in a job or several
+ jobs with fixed file paths, specify a `filename` for each of them to override
+ the default. If the ioengine is file based, you can specify a number of files
+ by separating the names with a ':' colon. So if you wanted a job to open
+ :file:`/dev/sda` and :file:`/dev/sdb` as the two working files, you would use
+ ``filename=/dev/sda:/dev/sdb``. This also means that whenever this option is
+ specified, :option:`nrfiles` is ignored. The size of regular files specified
+ by this option will be :option:`size` divided by number of files unless an
+ explicit size is specified by :option:`filesize`.
-It is also possible to get fio to dump the current output while it is
-running, without terminating the job. To do that, send fio the USR1 signal.
-You can also get regularly timed dumps by using the --status-interval
-parameter, or by creating a file in /tmp named fio-dump-status. If fio
-sees this file, it will unlink it and dump the current output status.
+ Each colon and backslash in the wanted path must be escaped with a ``\``
+ character. For instance, if the path is :file:`/dev/dsk/foo@3,0:c` then you
+ would use ``filename=/dev/dsk/foo@3,0\:c`` and if the path is
+ :file:`F:\\filename` then you would use ``filename=F\:\\filename``.
+ On Windows, disk devices are accessed as :file:`\\\\.\\PhysicalDrive0` for
+ the first device, :file:`\\\\.\\PhysicalDrive1` for the second etc.
+ Note: Windows and FreeBSD prevent write access to areas
+ of the disk containing in-use data (e.g. filesystems).
-7.0 Terse output
-----------------
+ The filename "`-`" is a reserved name, meaning *stdin* or *stdout*. Which
+ of the two depends on the read/write direction set.
-For scripted usage where you typically want to generate tables or graphs
-of the results, fio can output the results in a semicolon separated format.
-The format is one long line of values, such as:
+.. option:: filename_format=str
-2;card0;0;0;7139336;121836;60004;1;10109;27.932460;116.933948;220;126861;3495.446807;1085.368601;226;126864;3523.635629;1089.012448;24063;99944;50.275485%;59818.274627;5540.657370;7155060;122104;60004;1;8338;29.086342;117.839068;388;128077;5032.488518;1234.785715;391;128085;5061.839412;1236.909129;23436;100928;50.287926%;59964.832030;5644.844189;14.595833%;19.394167%;123706;0;7313;0.1%;0.1%;0.1%;0.1%;0.1%;0.1%;100.0%;0.00%;0.00%;0.00%;0.00%;0.00%;0.00%;0.01%;0.02%;0.05%;0.16%;6.04%;40.40%;52.68%;0.64%;0.01%;0.00%;0.01%;0.00%;0.00%;0.00%;0.00%;0.00%
-A description of this job goes here.
+ If sharing multiple files between jobs, it is usually necessary to have fio
+ generate the exact names that you want. By default, fio will name a file
+ based on the default file format specification of
+ :file:`jobname.jobnumber.filenumber`. With this option, that can be
+ customized. Fio will recognize and replace the following keywords in this
+ string:
-The job description (if provided) follows on a second line.
+ **$jobname**
+ The name of the worker thread or process.
+ **$jobnum**
+ The incremental number of the worker thread or process.
+ **$filenum**
+ The incremental number of the file for that worker thread or
+ process.
-To enable terse output, use the --minimal command line option. The first
-value is the version of the terse output format. If the output has to
-be changed for some reason, this number will be incremented by 1 to
-signify that change.
-
-Split up, the format is as follows:
-
- terse version, fio version, jobname, groupid, error
- READ status:
- Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
- Submission latency: min, max, mean, stdev (usec)
- Completion latency: min, max, mean, stdev (usec)
- Completion latency percentiles: 20 fields (see below)
- Total latency: min, max, mean, stdev (usec)
- Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev
- WRITE status:
- Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
- Submission latency: min, max, mean, stdev (usec)
- Completion latency: min, max, mean, stdev(usec)
- Completion latency percentiles: 20 fields (see below)
- Total latency: min, max, mean, stdev (usec)
- Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev
- CPU usage: user, system, context switches, major faults, minor faults
- IO depths: <=1, 2, 4, 8, 16, 32, >=64
- IO latencies microseconds: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
- IO latencies milliseconds: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
- Disk utilization: Disk name, Read ios, write ios,
- Read merges, write merges,
- Read ticks, write ticks,
- Time spent in queue, disk utilization percentage
- Additional Info (dependent on continue_on_error, default off): total # errors, first error code
-
- Additional Info (dependent on description being set): Text description
-
-Completion latency percentiles can be a grouping of up to 20 sets, so
-for the terse output fio writes all of them. Each field will look like this:
+ To have dependent jobs share a set of files, this option can be set to have
+ fio generate filenames that are shared between the two. For instance, if
+ :file:`testfiles.$filenum` is specified, file number 4 for any job will be
+ named :file:`testfiles.4`. The default of :file:`$jobname.$jobnum.$filenum`
+ will be used if no other format specifier is given.
- 1.00%=6112
+.. option:: unique_filename=bool
-which is the Xth percentile, and the usec latency associated with it.
+ To avoid collisions between networked clients, fio defaults to prefixing any
+ generated filenames (with a directory specified) with the source of the
+ client connecting. To disable this behavior, set this option to 0.
-For disk utilization, all disks used by fio are shown. So for each disk
-there will be a disk utilization section.
+.. option:: opendir=str
+ Recursively open any files below directory `str`.
-8.0 Trace file format
----------------------
-There are two trace file format that you can encounter. The older (v1) format
-is unsupported since version 1.20-rc3 (March 2008). It will still be described
-below in case that you get an old trace and want to understand it.
+.. option:: lockfile=str
-In any case the trace is a simple text file with a single action per line.
+ Fio defaults to not locking any files before it does I/O to them. If a file
+ or file descriptor is shared, fio can serialize I/O to that file to make the
+ end result consistent. This is usual for emulating real workloads that share
+ files. The lock modes are:
+ **none**
+ No locking. The default.
+ **exclusive**
+ Only one thread or process may do I/O at a time, excluding all
+ others.
+ **readwrite**
+ Read-write locking on the file. Many readers may
+ access the file at the same time, but writes get exclusive access.
-8.1 Trace file format v1
-------------------------
-Each line represents a single io action in the following format:
+.. option:: nrfiles=int
-rw, offset, length
+ Number of files to use for this job. Defaults to 1. The size of files
+ will be :option:`size` divided by this unless explicit size is specified by
+ :option:`filesize`. Files are created for each thread separately, and each
+ file will have a file number within its name by default, as explained in
+ :option:`filename` section.
-where rw=0/1 for read/write, and the offset and length entries being in bytes.
-This format is not supported in Fio versions => 1.20-rc3.
+.. option:: openfiles=int
+ Number of files to keep open at the same time. Defaults to the same as
+ :option:`nrfiles`, can be set smaller to limit the number simultaneous
+ opens.
-8.2 Trace file format v2
-------------------------
-The second version of the trace file format was added in Fio version 1.17.
-It allows to access more then one file per trace and has a bigger set of
-possible file actions.
+.. option:: file_service_type=str
-The first line of the trace file has to be:
+ Defines how fio decides which file from a job to service next. The following
+ types are defined:
-fio version 2 iolog
+ **random**
+ Choose a file at random.
-Following this can be lines in two different formats, which are described below.
+ **roundrobin**
+ Round robin over opened files. This is the default.
-The file management format:
+ **sequential**
+ Finish one file before moving on to the next. Multiple files can
+ still be open depending on 'openfiles'.
-filename action
+ **zipf**
+ Use a *Zipf* distribution to decide what file to access.
-The filename is given as an absolute path. The action can be one of these:
+ **pareto**
+ Use a *Pareto* distribution to decide what file to access.
-add Add the given filename to the trace
-open Open the file with the given filename. The filename has to have
- been added with the add action before.
-close Close the file with the given filename. The file has to have been
- opened before.
-
-
-The file io action format:
-
-filename action offset length
-
-The filename is given as an absolute path, and has to have been added and opened
-before it can be used with this format. The offset and length are given in
-bytes. The action can be one of these:
-
-wait Wait for 'offset' microseconds. Everything below 100 is discarded.
- The time is relative to the previous wait statement.
-read Read 'length' bytes beginning from 'offset'
-write Write 'length' bytes beginning from 'offset'
-sync fsync() the file
-datasync fdatasync() the file
-trim trim the given file from the given 'offset' for 'length' bytes
-
-
-9.0 CPU idleness profiling
---------------------------
-In some cases, we want to understand CPU overhead in a test. For example,
-we test patches for the specific goodness of whether they reduce CPU usage.
-fio implements a balloon approach to create a thread per CPU that runs at
-idle priority, meaning that it only runs when nobody else needs the cpu.
-By measuring the amount of work completed by the thread, idleness of each
-CPU can be derived accordingly.
-
-An unit work is defined as touching a full page of unsigned characters. Mean
-and standard deviation of time to complete an unit work is reported in "unit
-work" section. Options can be chosen to report detailed percpu idleness or
-overall system idleness by aggregating percpu stats.
-
-
-10.0 Verification and triggers
-------------------------------
-Fio is usually run in one of two ways, when data verification is done. The
-first is a normal write job of some sort with verify enabled. When the
-write phase has completed, fio switches to reads and verifies everything
-it wrote. The second model is running just the write phase, and then later
-on running the same job (but with reads instead of writes) to repeat the
-same IO patterns and verify the contents. Both of these methods depend
-on the write phase being completed, as fio otherwise has no idea how much
-data was written.
-
-With verification triggers, fio supports dumping the current write state
-to local files. Then a subsequent read verify workload can load this state
-and know exactly where to stop. This is useful for testing cases where
-power is cut to a server in a managed fashion, for instance.
+ **gauss**
+ Use a *Gaussian* (normal) distribution to decide what file to
+ access.
-A verification trigger consists of two things:
+ For *random*, *roundrobin*, and *sequential*, a postfix can be appended to
+ tell fio how many I/Os to issue before switching to a new file. For example,
+ specifying ``file_service_type=random:8`` would cause fio to issue
+ 8 I/Os before selecting a new file at random. For the non-uniform
+ distributions, a floating point postfix can be given to influence how the
+ distribution is skewed. See :option:`random_distribution` for a description
+ of how that would work.
-1) Storing the write state of each job
-2) Executing a trigger command
+.. option:: ioscheduler=str
-The write state is relatively small, on the order of hundreds of bytes
-to single kilobytes. It contains information on the number of completions
-done, the last X completions, etc.
+ Attempt to switch the device hosting the file to the specified I/O scheduler
+ before running.
-A trigger is invoked either through creation ('touch') of a specified
-file in the system, or through a timeout setting. If fio is run with
---trigger-file=/tmp/trigger-file, then it will continually check for
-the existence of /tmp/trigger-file. When it sees this file, it will
-fire off the trigger (thus saving state, and executing the trigger
-command).
+.. option:: create_serialize=bool
-For client/server runs, there's both a local and remote trigger. If
-fio is running as a server backend, it will send the job states back
-to the client for safe storage, then execute the remote trigger, if
-specified. If a local trigger is specified, the server will still send
-back the write state, but the client will then execute the trigger.
+ If true, serialize the file creation for the jobs. This may be handy to
+ avoid interleaving of data files, which may greatly depend on the filesystem
+ used and even the number of processors in the system. Default: true.
-10.1 Verification trigger example
----------------------------------
-Lets say we want to run a powercut test on the remote machine 'server'.
-Our write workload is in write-test.fio. We want to cut power to 'server'
-at some point during the run, and we'll run this test from the safety
-or our local machine, 'localbox'. On the server, we'll start the fio
-backend normally:
+.. option:: create_fsync=bool
-server# fio --server
+ :manpage:`fsync(2)` the data file after creation. This is the default.
-and on the client, we'll fire off the workload:
+.. option:: create_on_open=bool
-localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger-remote="bash -c \"echo b > /proc/sysrq-triger\""
+ If true, don't pre-create files but allow the job's open() to create a file
+ when it's time to do I/O. Default: false -- pre-create all necessary files
+ when the job starts.
-We set /tmp/my-trigger as the trigger file, and we tell fio to execute
+.. option:: create_only=bool
-echo b > /proc/sysrq-trigger
+ If true, fio will only run the setup phase of the job. If files need to be
+ laid out or updated on disk, only that will be done -- the actual job contents
+ are not executed. Default: false.
-on the server once it has received the trigger and sent us the write
-state. This will work, but it's not _really_ cutting power to the server,
-it's merely abruptly rebooting it. If we have a remote way of cutting
-power to the server through IPMI or similar, we could do that through
-a local trigger command instead. Lets assume we have a script that does
-IPMI reboot of a given hostname, ipmi-reboot. On localbox, we could
-then have run fio with a local trigger instead:
+.. option:: allow_file_create=bool
-localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger="ipmi-reboot server"
+ If true, fio is permitted to create files as part of its workload. If this
+ option is false, then fio will error out if
+ the files it needs to use don't already exist. Default: true.
-For this case, fio would wait for the server to send us the write state,
-then execute 'ipmi-reboot server' when that happened.
+.. option:: allow_mounted_write=bool
-10.2 Loading verify state
--------------------------
-To load store write state, read verification job file must contain
-the verify_state_load option. If that is set, fio will load the previously
-stored state. For a local fio run this is done by loading the files directly,
-and on a client/server run, the server backend will ask the client to send
-the files over and load them from there.
+ If this isn't set, fio will abort jobs that are destructive (e.g. that write)
+ to what appears to be a mounted device or partition. This should help catch
+ creating inadvertently destructive tests, not realizing that the test will
+ destroy data on the mounted file system. Note that some platforms don't allow
+ writing against a mounted device regardless of this option. Default: false.
+.. option:: pre_read=bool
-11.0 Log File Formats
----------------------
+ If this is given, files will be pre-read into memory before starting the
+ given I/O operation. This will also clear the :option:`invalidate` flag,
+ since it is pointless to pre-read and then drop the cache. This will only
+ work for I/O engines that are seek-able, since they allow you to read the
+ same data multiple times. Thus it will not work on non-seekable I/O engines
+ (e.g. network, splice). Default: false.
-Fio supports a variety of log file formats, for logging latencies, bandwidth,
-and IOPS. The logs share a common format, which looks like this:
+.. option:: unlink=bool
-time (msec), value, data direction, offset
+ Unlink the job files when done. Not the default, as repeated runs of that
+ job would then waste time recreating the file set again and again. Default:
+ false.
-Time for the log entry is always in milliseconds. The value logged depends
-on the type of log, it will be one of the following:
+.. option:: unlink_each_loop=bool
+
+ Unlink job files after each iteration or loop. Default: false.
+
+.. option:: zonesize=int
+
+ Divide a file into zones of the specified size. See :option:`zoneskip`.
+
+.. option:: zonerange=int
+
+ Give size of an I/O zone. See :option:`zoneskip`.
+
+.. option:: zoneskip=int
+
+ Skip the specified number of bytes when :option:`zonesize` data has been
+ read. The two zone options can be used to only do I/O on zones of a file.
+
+
+I/O type
+~~~~~~~~
+
+.. option:: direct=bool
+
+ If value is true, use non-buffered I/O. This is usually O_DIRECT. Note that
+ ZFS on Solaris doesn't support direct I/O. On Windows the synchronous
+ ioengines don't support direct I/O. Default: false.
+
+.. option:: atomic=bool
+
+ If value is true, attempt to use atomic direct I/O. Atomic writes are
+ guaranteed to be stable once acknowledged by the operating system. Only
+ Linux supports O_ATOMIC right now.
+
+.. option:: buffered=bool
+
+ If value is true, use buffered I/O. This is the opposite of the
+ :option:`direct` option. Defaults to true.
+
+.. option:: readwrite=str, rw=str
+
+ Type of I/O pattern. Accepted values are:
+
+ **read**
+ Sequential reads.
+ **write**
+ Sequential writes.
+ **trim**
+ Sequential trims (Linux block devices only).
+ **randread**
+ Random reads.
+ **randwrite**
+ Random writes.
+ **randtrim**
+ Random trims (Linux block devices only).
+ **rw,readwrite**
+ Sequential mixed reads and writes.
+ **randrw**
+ Random mixed reads and writes.
+ **trimwrite**
+ Sequential trim+write sequences. Blocks will be trimmed first,
+ then the same blocks will be written to.
+
+ Fio defaults to read if the option is not specified. For the mixed I/O
+ types, the default is to split them 50/50. For certain types of I/O the
+ result may still be skewed a bit, since the speed may be different.
+
+ It is possible to specify the number of I/Os to do before getting a new
+ offset by appending ``:<nr>`` to the end of the string given. For a
+ random read, it would look like ``rw=randread:8`` for passing in an offset
+ modifier with a value of 8. If the suffix is used with a sequential I/O
+ pattern, then the *<nr>* value specified will be **added** to the generated
+ offset for each I/O turning sequential I/O into sequential I/O with holes.
+ For instance, using ``rw=write:4k`` will skip 4k for every write. Also see
+ the :option:`rw_sequencer` option.
+
+.. option:: rw_sequencer=str
+
+ If an offset modifier is given by appending a number to the ``rw=<str>``
+ line, then this option controls how that number modifies the I/O offset
+ being generated. Accepted values are:
+
+ **sequential**
+ Generate sequential offset.
+ **identical**
+ Generate the same offset.
+
+ ``sequential`` is only useful for random I/O, where fio would normally
+ generate a new random offset for every I/O. If you append e.g. 8 to randread,
+ you would get a new random offset for every 8 I/O's. The result would be a
+ seek for only every 8 I/O's, instead of for every I/O. Use ``rw=randread:8``
+ to specify that. As sequential I/O is already sequential, setting
+ ``sequential`` for that would not result in any differences. ``identical``
+ behaves in a similar fashion, except it sends the same offset 8 number of
+ times before generating a new offset.
+
+.. option:: unified_rw_reporting=bool
+
+ Fio normally reports statistics on a per data direction basis, meaning that
+ reads, writes, and trims are accounted and reported separately. If this
+ option is set fio sums the results and report them as "mixed" instead.
+
+.. option:: randrepeat=bool
+
+ Seed the random number generator used for random I/O patterns in a
+ predictable way so the pattern is repeatable across runs. Default: true.
+
+.. option:: allrandrepeat=bool
+
+ Seed all random number generators in a predictable way so results are
+ repeatable across runs. Default: false.
+
+.. option:: randseed=int
+
+ Seed the random number generators based on this seed value, to be able to
+ control what sequence of output is being generated. If not set, the random
+ sequence depends on the :option:`randrepeat` setting.
+
+.. option:: fallocate=str
+
+ Whether pre-allocation is performed when laying down files.
+ Accepted values are:
+
+ **none**
+ Do not pre-allocate space.
+
+ **posix**
+ Pre-allocate via :manpage:`posix_fallocate(3)`.
+
+ **keep**
+ Pre-allocate via :manpage:`fallocate(2)` with
+ FALLOC_FL_KEEP_SIZE set.
+
+ **0**
+ Backward-compatible alias for **none**.
+
+ **1**
+ Backward-compatible alias for **posix**.
+
+ May not be available on all supported platforms. **keep** is only available
+ on Linux. If using ZFS on Solaris this must be set to **none** because ZFS
+ doesn't support it. Default: **posix**.
+
+.. option:: fadvise_hint=str
+
+ Use :manpage:`posix_fadvise(2)` to advise the kernel on what I/O patterns
+ are likely to be issued. Accepted values are:
+
+ **0**
+ Backwards-compatible hint for "no hint".
+
+ **1**
+ Backwards compatible hint for "advise with fio workload type". This
+ uses **FADV_RANDOM** for a random workload, and **FADV_SEQUENTIAL**
+ for a sequential workload.
+
+ **sequential**
+ Advise using **FADV_SEQUENTIAL**.
+
+ **random**
+ Advise using **FADV_RANDOM**.
+
+.. option:: fadvise_stream=int
+
+ Use :manpage:`posix_fadvise(2)` to advise the kernel what stream ID the
+ writes issued belong to. Only supported on Linux. Note, this option may
+ change going forward.
+
+.. option:: offset=int
+
+ Start I/O at the provided offset in the file, given as either a fixed size in
+ bytes or a percentage. If a percentage is given, the next ``blockalign``-ed
+ offset will be used. Data before the given offset will not be touched. This
+ effectively caps the file size at `real_size - offset`. Can be combined with
+ :option:`size` to constrain the start and end range of the I/O workload.
+ A percentage can be specified by the percentage number plus 1 with preceding '-'.
+ For example, -1 is parsed as 0%, -10 is parsed as 9%, -101 is parsed as 100%.
+
+.. option:: offset_increment=int
+
+ If this is provided, then the real offset becomes `offset + offset_increment
+ * thread_number`, where the thread number is a counter that starts at 0 and
+ is incremented for each sub-job (i.e. when :option:`numjobs` option is
+ specified). This option is useful if there are several jobs which are
+ intended to operate on a file in parallel disjoint segments, with even
+ spacing between the starting points.
+
+.. option:: number_ios=int
+
+ Fio will normally perform I/Os until it has exhausted the size of the region
+ set by :option:`size`, or if it exhaust the allocated time (or hits an error
+ condition). With this setting, the range/size can be set independently of
+ the number of I/Os to perform. When fio reaches this number, it will exit
+ normally and report status. Note that this does not extend the amount of I/O
+ that will be done, it will only stop fio if this condition is met before
+ other end-of-job criteria.
+
+.. option:: fsync=int
+
+ If writing to a file, issue an :manpage:`fsync(2)` (or its equivalent) of
+ the dirty data for every number of blocks given. For example, if you give 32
+ as a parameter, fio will sync the file after every 32 writes issued. If fio is
+ using non-buffered I/O, we may not sync the file. The exception is the sg
+ I/O engine, which synchronizes the disk cache anyway. Defaults to 0, which
+ means fio does not periodically issue and wait for a sync to complete. Also
+ see :option:`end_fsync` and :option:`fsync_on_close`.
+
+.. option:: fdatasync=int
+
+ Like :option:`fsync` but uses :manpage:`fdatasync(2)` to only sync data and
+ not metadata blocks. In Windows, FreeBSD, and DragonFlyBSD there is no
+ :manpage:`fdatasync(2)` so this falls back to using :manpage:`fsync(2)`.
+ Defaults to 0, which means fio does not periodically issue and wait for a
+ data-only sync to complete.
+
+.. option:: write_barrier=int
+
+ Make every `N-th` write a barrier write.
+
+.. option:: sync_file_range=str:val
+
+ Use :manpage:`sync_file_range(2)` for every `val` number of write
+ operations. Fio will track range of writes that have happened since the last
+ :manpage:`sync_file_range(2)` call. `str` can currently be one or more of:
+
+ **wait_before**
+ SYNC_FILE_RANGE_WAIT_BEFORE
+ **write**
+ SYNC_FILE_RANGE_WRITE
+ **wait_after**
+ SYNC_FILE_RANGE_WAIT_AFTER
+
+ So if you do ``sync_file_range=wait_before,write:8``, fio would use
+ ``SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE`` for every 8
+ writes. Also see the :manpage:`sync_file_range(2)` man page. This option is
+ Linux specific.
+
+.. option:: overwrite=bool
+
+ If true, writes to a file will always overwrite existing data. If the file
+ doesn't already exist, it will be created before the write phase begins. If
+ the file exists and is large enough for the specified write phase, nothing
+ will be done. Default: false.
+
+.. option:: end_fsync=bool
+
+ If true, :manpage:`fsync(2)` file contents when a write stage has completed.
+ Default: false.
+
+.. option:: fsync_on_close=bool
+
+ If true, fio will :manpage:`fsync(2)` a dirty file on close. This differs
+ from :option:`end_fsync` in that it will happen on every file close, not
+ just at the end of the job. Default: false.
+
+.. option:: rwmixread=int
+
+ Percentage of a mixed workload that should be reads. Default: 50.
+
+.. option:: rwmixwrite=int
+
+ Percentage of a mixed workload that should be writes. If both
+ :option:`rwmixread` and :option:`rwmixwrite` is given and the values do not
+ add up to 100%, the latter of the two will be used to override the
+ first. This may interfere with a given rate setting, if fio is asked to
+ limit reads or writes to a certain rate. If that is the case, then the
+ distribution may be skewed. Default: 50.
+
+.. option:: random_distribution=str:float[,str:float][,str:float]
+
+ By default, fio will use a completely uniform random distribution when asked
+ to perform random I/O. Sometimes it is useful to skew the distribution in
+ specific ways, ensuring that some parts of the data is more hot than others.
+ fio includes the following distribution models:
+
+ **random**
+ Uniform random distribution
+
+ **zipf**
+ Zipf distribution
+
+ **pareto**
+ Pareto distribution
+
+ **gauss**
+ Normal (Gaussian) distribution
+
+ **zoned**
+ Zoned random distribution
+
+ When using a **zipf** or **pareto** distribution, an input value is also
+ needed to define the access pattern. For **zipf**, this is the `zipf
+ theta`. For **pareto**, it's the `Pareto power`. Fio includes a test
+ program, :command:`genzipf`, that can be used visualize what the given input
+ values will yield in terms of hit rates. If you wanted to use **zipf** with
+ a `theta` of 1.2, you would use ``random_distribution=zipf:1.2`` as the
+ option. If a non-uniform model is used, fio will disable use of the random
+ map. For the **gauss** distribution, a normal deviation is supplied as a
+ value between 0 and 100.
+
+ For a **zoned** distribution, fio supports specifying percentages of I/O
+ access that should fall within what range of the file or device. For
+ example, given a criteria of:
+
+ * 60% of accesses should be to the first 10%
+ * 30% of accesses should be to the next 20%
+ * 8% of accesses should be to to the next 30%
+ * 2% of accesses should be to the next 40%
+
+ we can define that through zoning of the random accesses. For the above
+ example, the user would do::
+
+ random_distribution=zoned:60/10:30/20:8/30:2/40
+
+ similarly to how :option:`bssplit` works for setting ranges and percentages
+ of block sizes. Like :option:`bssplit`, it's possible to specify separate
+ zones for reads, writes, and trims. If just one set is given, it'll apply to
+ all of them.
+
+.. option:: percentage_random=int[,int][,int]
+
+ For a random workload, set how big a percentage should be random. This
+ defaults to 100%, in which case the workload is fully random. It can be set
+ from anywhere from 0 to 100. Setting it to 0 would make the workload fully
+ sequential. Any setting in between will result in a random mix of sequential
+ and random I/O, at the given percentages. Comma-separated values may be
+ specified for reads, writes, and trims as described in :option:`blocksize`.
+
+.. option:: norandommap
+
+ Normally fio will cover every block of the file when doing random I/O. If
+ this option is given, fio will just get a new random offset without looking
+ at past I/O history. This means that some blocks may not be read or written,
+ and that some blocks may be read/written more than once. If this option is
+ used with :option:`verify` and multiple blocksizes (via :option:`bsrange`),
+ only intact blocks are verified, i.e., partially-overwritten blocks are
+ ignored.
+
+.. option:: softrandommap=bool
+
+ See :option:`norandommap`. If fio runs with the random block map enabled and
+ it fails to allocate the map, if this option is set it will continue without
+ a random block map. As coverage will not be as complete as with random maps,
+ this option is disabled by default.
+
+.. option:: random_generator=str
+
+ Fio supports the following engines for generating
+ I/O offsets for random I/O:
+
+ **tausworthe**
+ Strong 2^88 cycle random number generator
+ **lfsr**
+ Linear feedback shift register generator
+ **tausworthe64**
+ Strong 64-bit 2^258 cycle random number generator
+
+ **tausworthe** is a strong random number generator, but it requires tracking
+ on the side if we want to ensure that blocks are only read or written
+ once. **LFSR** guarantees that we never generate the same offset twice, and
+ it's also less computationally expensive. It's not a true random generator,
+ however, though for I/O purposes it's typically good enough. **LFSR** only
+ works with single block sizes, not with workloads that use multiple block
+ sizes. If used with such a workload, fio may read or write some blocks
+ multiple times. The default value is **tausworthe**, unless the required
+ space exceeds 2^32 blocks. If it does, then **tausworthe64** is
+ selected automatically.
+
+
+Block size
+~~~~~~~~~~
+
+.. option:: blocksize=int[,int][,int], bs=int[,int][,int]
+
+ The block size in bytes used for I/O units. Default: 4096. A single value
+ applies to reads, writes, and trims. Comma-separated values may be
+ specified for reads, writes, and trims. A value not terminated in a comma
+ applies to subsequent types.
+
+ Examples:
+
+ **bs=256k**
+ means 256k for reads, writes and trims.
+
+ **bs=8k,32k**
+ means 8k for reads, 32k for writes and trims.
+
+ **bs=8k,32k,**
+ means 8k for reads, 32k for writes, and default for trims.
+
+ **bs=,8k**
+ means default for reads, 8k for writes and trims.
+
+ **bs=,8k,**
+ means default for reads, 8k for writes, and default for trims.
+
+.. option:: blocksize_range=irange[,irange][,irange], bsrange=irange[,irange][,irange]
+
+ A range of block sizes in bytes for I/O units. The issued I/O unit will
+ always be a multiple of the minimum size, unless
+ :option:`blocksize_unaligned` is set.
+
+ Comma-separated ranges may be specified for reads, writes, and trims as
+ described in :option:`blocksize`.
+
+ Example: ``bsrange=1k-4k,2k-8k``.
+
+.. option:: bssplit=str[,str][,str]
+
+ Sometimes you want even finer grained control of the block sizes issued, not
+ just an even split between them. This option allows you to weight various
+ block sizes, so that you are able to define a specific amount of block sizes
+ issued. The format for this option is::
+
+ bssplit=blocksize/percentage:blocksize/percentage
+
+ for as many block sizes as needed. So if you want to define a workload that
+ has 50% 64k blocks, 10% 4k blocks, and 40% 32k blocks, you would write::
+
+ bssplit=4k/10:64k/50:32k/40
+
+ Ordering does not matter. If the percentage is left blank, fio will fill in
+ the remaining values evenly. So a bssplit option like this one::
+
+ bssplit=4k/50:1k/:32k/
+
+ would have 50% 4k ios, and 25% 1k and 32k ios. The percentages always add up
+ to 100, if bssplit is given a range that adds up to more, it will error out.
+
+ Comma-separated values may be specified for reads, writes, and trims as
+ described in :option:`blocksize`.
+
+ If you want a workload that has 50% 2k reads and 50% 4k reads, while having
+ 90% 4k writes and 10% 8k writes, you would specify::
+
+ bssplit=2k/50:4k/50,4k/90,8k/10
+
+.. option:: blocksize_unaligned, bs_unaligned
+
+ If set, fio will issue I/O units with any size within
+ :option:`blocksize_range`, not just multiples of the minimum size. This
+ typically won't work with direct I/O, as that normally requires sector
+ alignment.
+
+.. option:: bs_is_seq_rand
+
+ If this option is set, fio will use the normal read,write blocksize settings
+ as sequential,random blocksize settings instead. Any random read or write
+ will use the WRITE blocksize settings, and any sequential read or write will
+ use the READ blocksize settings.
+
+.. option:: blockalign=int[,int][,int], ba=int[,int][,int]
+
+ Boundary to which fio will align random I/O units. Default:
+ :option:`blocksize`. Minimum alignment is typically 512b for using direct
+ I/O, though it usually depends on the hardware block size. This option is
+ mutually exclusive with using a random map for files, so it will turn off
+ that option. Comma-separated values may be specified for reads, writes, and
+ trims as described in :option:`blocksize`.
+
+
+Buffers and memory
+~~~~~~~~~~~~~~~~~~
+
+.. option:: zero_buffers
+
+ Initialize buffers with all zeros. Default: fill buffers with random data.
+
+.. option:: refill_buffers
+
+ If this option is given, fio will refill the I/O buffers on every
+ submit. The default is to only fill it at init time and reuse that
+ data. Only makes sense if zero_buffers isn't specified, naturally. If data
+ verification is enabled, `refill_buffers` is also automatically enabled.
+
+.. option:: scramble_buffers=bool
+
+ If :option:`refill_buffers` is too costly and the target is using data
+ deduplication, then setting this option will slightly modify the I/O buffer
+ contents to defeat normal de-dupe attempts. This is not enough to defeat
+ more clever block compression attempts, but it will stop naive dedupe of
+ blocks. Default: true.
+
+.. option:: buffer_compress_percentage=int
+
+ If this is set, then fio will attempt to provide I/O buffer content (on
+ WRITEs) that compresses to the specified level. Fio does this by providing a
+ mix of random data and a fixed pattern. The fixed pattern is either zeros,
+ or the pattern specified by :option:`buffer_pattern`. If the pattern option
+ is used, it might skew the compression ratio slightly. Note that this is per
+ block size unit, for file/disk wide compression level that matches this
+ setting, you'll also want to set :option:`refill_buffers`.
+
+.. option:: buffer_compress_chunk=int
+
+ See :option:`buffer_compress_percentage`. This setting allows fio to manage
+ how big the ranges of random data and zeroed data is. Without this set, fio
+ will provide :option:`buffer_compress_percentage` of blocksize random data,
+ followed by the remaining zeroed. With this set to some chunk size smaller
+ than the block size, fio can alternate random and zeroed data throughout the
+ I/O buffer.
+
+.. option:: buffer_pattern=str
+
+ If set, fio will fill the I/O buffers with this pattern or with the contents
+ of a file. If not set, the contents of I/O buffers are defined by the other
+ options related to buffer contents. The setting can be any pattern of bytes,
+ and can be prefixed with 0x for hex values. It may also be a string, where
+ the string must then be wrapped with ``""``. Or it may also be a filename,
+ where the filename must be wrapped with ``''`` in which case the file is
+ opened and read. Note that not all the file contents will be read if that
+ would cause the buffers to overflow. So, for example::
+
+ buffer_pattern='filename'
+
+ or::
+
+ buffer_pattern="abcd"
+
+ or::
+
+ buffer_pattern=-12
+
+ or::
+
+ buffer_pattern=0xdeadface
+
+ Also you can combine everything together in any order::
+
+ buffer_pattern=0xdeadface"abcd"-12'filename'
+
+.. option:: dedupe_percentage=int
+
+ If set, fio will generate this percentage of identical buffers when
+ writing. These buffers will be naturally dedupable. The contents of the
+ buffers depend on what other buffer compression settings have been set. It's
+ possible to have the individual buffers either fully compressible, or not at
+ all. This option only controls the distribution of unique buffers.
+
+.. option:: invalidate=bool
+
+ Invalidate the buffer/page cache parts of the files to be used prior to
+ starting I/O if the platform and file type support it. Defaults to true.
+ This will be ignored if :option:`pre_read` is also specified for the
+ same job.
+
+.. option:: sync=bool
+
+ Use synchronous I/O for buffered writes. For the majority of I/O engines,
+ this means using O_SYNC. Default: false.
+
+.. option:: iomem=str, mem=str
+
+ Fio can use various types of memory as the I/O unit buffer. The allowed
+ values are:
+
+ **malloc**
+ Use memory from :manpage:`malloc(3)` as the buffers. Default memory
+ type.
+
+ **shm**
+ Use shared memory as the buffers. Allocated through
+ :manpage:`shmget(2)`.
+
+ **shmhuge**
+ Same as shm, but use huge pages as backing.
+
+ **mmap**
+ Use :manpage:`mmap(2)` to allocate buffers. May either be anonymous memory, or can
+ be file backed if a filename is given after the option. The format
+ is `mem=mmap:/path/to/file`.
+
+ **mmaphuge**
+ Use a memory mapped huge file as the buffer backing. Append filename
+ after mmaphuge, ala `mem=mmaphuge:/hugetlbfs/file`.
+
+ **mmapshared**
+ Same as mmap, but use a MMAP_SHARED mapping.
+
+ **cudamalloc**
+ Use GPU memory as the buffers for GPUDirect RDMA benchmark.
+
+ The area allocated is a function of the maximum allowed bs size for the job,
+ multiplied by the I/O depth given. Note that for **shmhuge** and
+ **mmaphuge** to work, the system must have free huge pages allocated. This
+ can normally be checked and set by reading/writing
+ :file:`/proc/sys/vm/nr_hugepages` on a Linux system. Fio assumes a huge page
+ is 4MiB in size. So to calculate the number of huge pages you need for a
+ given job file, add up the I/O depth of all jobs (normally one unless
+ :option:`iodepth` is used) and multiply by the maximum bs set. Then divide
+ that number by the huge page size. You can see the size of the huge pages in
+ :file:`/proc/meminfo`. If no huge pages are allocated by having a non-zero
+ number in `nr_hugepages`, using **mmaphuge** or **shmhuge** will fail. Also
+ see :option:`hugepage-size`.
+
+ **mmaphuge** also needs to have hugetlbfs mounted and the file location
+ should point there. So if it's mounted in :file:`/huge`, you would use
+ `mem=mmaphuge:/huge/somefile`.
+
+.. option:: iomem_align=int
+
+ This indicates the memory alignment of the I/O memory buffers. Note that
+ the given alignment is applied to the first I/O unit buffer, if using
+ :option:`iodepth` the alignment of the following buffers are given by the
+ :option:`bs` used. In other words, if using a :option:`bs` that is a
+ multiple of the page sized in the system, all buffers will be aligned to
+ this value. If using a :option:`bs` that is not page aligned, the alignment
+ of subsequent I/O memory buffers is the sum of the :option:`iomem_align` and
+ :option:`bs` used.
+
+.. option:: hugepage-size=int
+
+ Defines the size of a huge page. Must at least be equal to the system
+ setting, see :file:`/proc/meminfo`. Defaults to 4MiB. Should probably
+ always be a multiple of megabytes, so using ``hugepage-size=Xm`` is the
+ preferred way to set this to avoid setting a non-pow-2 bad value.
+
+.. option:: lockmem=int
+
+ Pin the specified amount of memory with :manpage:`mlock(2)`. Can be used to
+ simulate a smaller amount of memory. The amount specified is per worker.
+
+
+I/O size
+~~~~~~~~
+
+.. option:: size=int
+
+ The total size of file I/O for each thread of this job. Fio will run until
+ this many bytes has been transferred, unless runtime is limited by other options
+ (such as :option:`runtime`, for instance, or increased/decreased by :option:`io_size`).
+ Fio will divide this size between the available files determined by options
+ such as :option:`nrfiles`, :option:`filename`, unless :option:`filesize` is
+ specified by the job. If the result of division happens to be 0, the size is
+ set to the physical size of the given files or devices if they exist.
+ If this option is not specified, fio will use the full size of the given
+ files or devices. If the files do not exist, size must be given. It is also
+ possible to give size as a percentage between 1 and 100. If ``size=20%`` is
+ given, fio will use 20% of the full size of the given files or devices.
+ Can be combined with :option:`offset` to constrain the start and end range
+ that I/O will be done within.
+
+.. option:: io_size=int, io_limit=int
+
+ Normally fio operates within the region set by :option:`size`, which means
+ that the :option:`size` option sets both the region and size of I/O to be
+ performed. Sometimes that is not what you want. With this option, it is
+ possible to define just the amount of I/O that fio should do. For instance,
+ if :option:`size` is set to 20GiB and :option:`io_size` is set to 5GiB, fio
+ will perform I/O within the first 20GiB but exit when 5GiB have been
+ done. The opposite is also possible -- if :option:`size` is set to 20GiB,
+ and :option:`io_size` is set to 40GiB, then fio will do 40GiB of I/O within
+ the 0..20GiB region.
+
+.. option:: filesize=irange(int)
+
+ Individual file sizes. May be a range, in which case fio will select sizes
+ for files at random within the given range and limited to :option:`size` in
+ total (if that is given). If not given, each created file is the same size.
+ This option overrides :option:`size` in terms of file size, which means
+ this value is used as a fixed size or possible range of each file.
+
+.. option:: file_append=bool
+
+ Perform I/O after the end of the file. Normally fio will operate within the
+ size of a file. If this option is set, then fio will append to the file
+ instead. This has identical behavior to setting :option:`offset` to the size
+ of a file. This option is ignored on non-regular files.
+
+.. option:: fill_device=bool, fill_fs=bool
+
+ Sets size to something really large and waits for ENOSPC (no space left on
+ device) as the terminating condition. Only makes sense with sequential
+ write. For a read workload, the mount point will be filled first then I/O
+ started on the result. This option doesn't make sense if operating on a raw
+ device node, since the size of that is already known by the file system.
+ Additionally, writing beyond end-of-device will not return ENOSPC there.
+
+
+I/O engine
+~~~~~~~~~~
+
+.. option:: ioengine=str
+
+ Defines how the job issues I/O to the file. The following types are defined:
+
+ **sync**
+ Basic :manpage:`read(2)` or :manpage:`write(2)`
+ I/O. :manpage:`lseek(2)` is used to position the I/O location.
+ See :option:`fsync` and :option:`fdatasync` for syncing write I/Os.
+
+ **psync**
+ Basic :manpage:`pread(2)` or :manpage:`pwrite(2)` I/O. Default on
+ all supported operating systems except for Windows.
+
+ **vsync**
+ Basic :manpage:`readv(2)` or :manpage:`writev(2)` I/O. Will emulate
+ queuing by coalescing adjacent I/Os into a single submission.
+
+ **pvsync**
+ Basic :manpage:`preadv(2)` or :manpage:`pwritev(2)` I/O.
+
+ **pvsync2**
+ Basic :manpage:`preadv2(2)` or :manpage:`pwritev2(2)` I/O.
+
+ **libaio**
+ Linux native asynchronous I/O. Note that Linux may only support
+ queued behavior with non-buffered I/O (set ``direct=1`` or
+ ``buffered=0``).
+ This engine defines engine specific options.
+
+ **posixaio**
+ POSIX asynchronous I/O using :manpage:`aio_read(3)` and
+ :manpage:`aio_write(3)`.
+
+ **solarisaio**
+ Solaris native asynchronous I/O.
+
+ **windowsaio**
+ Windows native asynchronous I/O. Default on Windows.
+
+ **mmap**
+ File is memory mapped with :manpage:`mmap(2)` and data copied
+ to/from using :manpage:`memcpy(3)`.
+
+ **splice**
+ :manpage:`splice(2)` is used to transfer the data and
+ :manpage:`vmsplice(2)` to transfer data from user space to the
+ kernel.
+
+ **sg**
+ SCSI generic sg v3 I/O. May either be synchronous using the SG_IO
+ ioctl, or if the target is an sg character device we use
+ :manpage:`read(2)` and :manpage:`write(2)` for asynchronous
+ I/O. Requires filename option to specify either block or character
+ devices.
+
+ **null**
+ Doesn't transfer any data, just pretends to. This is mainly used to
+ exercise fio itself and for debugging/testing purposes.
+
+ **net**
+ Transfer over the network to given ``host:port``. Depending on the
+ :option:`protocol` used, the :option:`hostname`, :option:`port`,
+ :option:`listen` and :option:`filename` options are used to specify
+ what sort of connection to make, while the :option:`protocol` option
+ determines which protocol will be used. This engine defines engine
+ specific options.
+
+ **netsplice**
+ Like **net**, but uses :manpage:`splice(2)` and
+ :manpage:`vmsplice(2)` to map data and send/receive.
+ This engine defines engine specific options.
+
+ **cpuio**
+ Doesn't transfer any data, but burns CPU cycles according to the
+ :option:`cpuload` and :option:`cpuchunks` options. Setting
+ :option:`cpuload`\=85 will cause that job to do nothing but burn 85%
+ of the CPU. In case of SMP machines, use :option:`numjobs`
+ =<no_of_cpu> to get desired CPU usage, as the cpuload only loads a
+ single CPU at the desired rate. A job never finishes unless there is
+ at least one non-cpuio job.
+
+ **guasi**
+ The GUASI I/O engine is the Generic Userspace Asyncronous Syscall
+ Interface approach to async I/O. See
+
+ http://www.xmailserver.org/guasi-lib.html
+
+ for more info on GUASI.
+
+ **rdma**
+ The RDMA I/O engine supports both RDMA memory semantics
+ (RDMA_WRITE/RDMA_READ) and channel semantics (Send/Recv) for the
+ InfiniBand, RoCE and iWARP protocols.
+
+ **falloc**
+ I/O engine that does regular fallocate to simulate data transfer as
+ fio ioengine.
+
+ DDIR_READ
+ does fallocate(,mode = FALLOC_FL_KEEP_SIZE,).
+
+ DDIR_WRITE
+ does fallocate(,mode = 0).
+
+ DDIR_TRIM
+ does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE).
+
+ **ftruncate**
+ I/O engine that sends :manpage:`ftruncate(2)` operations in response
+ to write (DDIR_WRITE) events. Each ftruncate issued sets the file's
+ size to the current block offset. Block size is ignored.
+
+ **e4defrag**
+ I/O engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate
+ defragment activity in request to DDIR_WRITE event.
+
+ **rbd**
+ I/O engine supporting direct access to Ceph Rados Block Devices
+ (RBD) via librbd without the need to use the kernel rbd driver. This
+ ioengine defines engine specific options.
+
+ **gfapi**
+ Using GlusterFS libgfapi sync interface to direct access to
+ GlusterFS volumes without having to go through FUSE. This ioengine
+ defines engine specific options.
+
+ **gfapi_async**
+ Using GlusterFS libgfapi async interface to direct access to
+ GlusterFS volumes without having to go through FUSE. This ioengine
+ defines engine specific options.
+
+ **libhdfs**
+ Read and write through Hadoop (HDFS). The :file:`filename` option
+ is used to specify host,port of the hdfs name-node to connect. This
+ engine interprets offsets a little differently. In HDFS, files once
+ created cannot be modified so random writes are not possible. To
+ imitate this the libhdfs engine expects a bunch of small files to be
+ created over HDFS and will randomly pick a file from them
+ based on the offset generated by fio backend (see the example
+ job file to create such files, use ``rw=write`` option). Please
+ note, it may be necessary to set environment variables to work
+ with HDFS/libhdfs properly. Each job uses its own connection to
+ HDFS.
+
+ **mtd**
+ Read, write and erase an MTD character device (e.g.,
+ :file:`/dev/mtd0`). Discards are treated as erases. Depending on the
+ underlying device type, the I/O may have to go in a certain pattern,
+ e.g., on NAND, writing sequentially to erase blocks and discarding
+ before overwriting. The `trimwrite` mode works well for this
+ constraint.
+
+ **pmemblk**
+ Read and write using filesystem DAX to a file on a filesystem
+ mounted with DAX on a persistent memory device through the NVML
+ libpmemblk library.
+
+ **dev-dax**
+ Read and write using device DAX to a persistent memory device (e.g.,
+ /dev/dax0.0) through the NVML libpmem library.
+
+ **external**
+ Prefix to specify loading an external I/O engine object file. Append
+ the engine filename, e.g. ``ioengine=external:/tmp/foo.o`` to load
+ ioengine :file:`foo.o` in :file:`/tmp`.
+
+
+I/O engine specific parameters
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In addition, there are some parameters which are only valid when a specific
+ioengine is in use. These are used identically to normal parameters, with the
+caveat that when used on the command line, they must come after the
+:option:`ioengine` that defines them is selected.
+
+.. option:: userspace_reap : [libaio]
+
+ Normally, with the libaio engine in use, fio will use the
+ :manpage:`io_getevents(2)` system call to reap newly returned events. With
+ this flag turned on, the AIO ring will be read directly from user-space to
+ reap events. The reaping mode is only enabled when polling for a minimum of
+ 0 events (e.g. when :option:`iodepth_batch_complete` `=0`).
+
+.. option:: hipri : [pvsync2]
+
+ Set RWF_HIPRI on I/O, indicating to the kernel that it's of higher priority
+ than normal.
+
+.. option:: cpuload=int : [cpuio]
+
+ Attempt to use the specified percentage of CPU cycles. This is a mandatory
+ option when using cpuio I/O engine.
+
+.. option:: cpuchunks=int : [cpuio]
+
+ Split the load into cycles of the given time. In microseconds.
+
+.. option:: exit_on_io_done=bool : [cpuio]
+
+ Detect when I/O threads are done, then exit.
+
+.. option:: hostname=str : [netsplice] [net]
+
+ The hostname or IP address to use for TCP or UDP based I/O. If the job is
+ a TCP listener or UDP reader, the hostname is not used and must be omitted
+ unless it is a valid UDP multicast address.
+
+.. option:: namenode=str : [libhdfs]
+
+ The hostname or IP address of a HDFS cluster namenode to contact.
+
+.. option:: port=int
+
+ [netsplice], [net]
+
+ The TCP or UDP port to bind to or connect to. If this is used with
+ :option:`numjobs` to spawn multiple instances of the same job type, then
+ this will be the starting port number since fio will use a range of
+ ports.
+
+ [libhdfs]
+
+ the listening port of the HFDS cluster namenode.
+
+.. option:: interface=str : [netsplice] [net]
+
+ The IP address of the network interface used to send or receive UDP
+ multicast.
+
+.. option:: ttl=int : [netsplice] [net]
+
+ Time-to-live value for outgoing UDP multicast packets. Default: 1.
+
+.. option:: nodelay=bool : [netsplice] [net]
+
+ Set TCP_NODELAY on TCP connections.
+
+.. option:: protocol=str : [netsplice] [net]
+
+.. option:: proto=str : [netsplice] [net]
+
+ The network protocol to use. Accepted values are:
+
+ **tcp**
+ Transmission control protocol.
+ **tcpv6**
+ Transmission control protocol V6.
+ **udp**
+ User datagram protocol.
+ **udpv6**
+ User datagram protocol V6.
+ **unix**
+ UNIX domain socket.
+
+ When the protocol is TCP or UDP, the port must also be given, as well as the
+ hostname if the job is a TCP listener or UDP reader. For unix sockets, the
+ normal filename option should be used and the port is invalid.
+
+.. option:: listen : [net]
+
+ For TCP network connections, tell fio to listen for incoming connections
+ rather than initiating an outgoing connection. The :option:`hostname` must
+ be omitted if this option is used.
+
+.. option:: pingpong : [net]
+
+ Normally a network writer will just continue writing data, and a network
+ reader will just consume packages. If ``pingpong=1`` is set, a writer will
+ send its normal payload to the reader, then wait for the reader to send the
+ same payload back. This allows fio to measure network latencies. The
+ submission and completion latencies then measure local time spent sending or
+ receiving, and the completion latency measures how long it took for the
+ other end to receive and send back. For UDP multicast traffic
+ ``pingpong=1`` should only be set for a single reader when multiple readers
+ are listening to the same address.
+
+.. option:: window_size : [net]
+
+ Set the desired socket buffer size for the connection.
+
+.. option:: mss : [net]
+
+ Set the TCP maximum segment size (TCP_MAXSEG).
+
+.. option:: donorname=str : [e4defrag]
+
+ File will be used as a block donor (swap extents between files).
+
+.. option:: inplace=int : [e4defrag]
+
+ Configure donor file blocks allocation strategy:
+
+ **0**
+ Default. Preallocate donor's file on init.
+ **1**
+ Allocate space immediately inside defragment event, and free right
+ after event.
+
+.. option:: clustername=str : [rbd]
+
+ Specifies the name of the Ceph cluster.
+
+.. option:: rbdname=str : [rbd]
+
+ Specifies the name of the RBD.
+
+.. option:: pool=str : [rbd]
+
+ Specifies the name of the Ceph pool containing RBD.
+
+.. option:: clientname=str : [rbd]
+
+ Specifies the username (without the 'client.' prefix) used to access the
+ Ceph cluster. If the *clustername* is specified, the *clientname* shall be
+ the full *type.id* string. If no type. prefix is given, fio will add
+ 'client.' by default.
+
+.. option:: skip_bad=bool : [mtd]
+
+ Skip operations against known bad blocks.
+
+.. option:: hdfsdirectory : [libhdfs]
+
+ libhdfs will create chunk in this HDFS directory.
+
+.. option:: chunk_size : [libhdfs]
+
+ the size of the chunk to use for each file.
+
+
+I/O depth
+~~~~~~~~~
+
+.. option:: iodepth=int
+
+ Number of I/O units to keep in flight against the file. Note that
+ increasing *iodepth* beyond 1 will not affect synchronous ioengines (except
+ for small degrees when :option:`verify_async` is in use). Even async
+ engines may impose OS restrictions causing the desired depth not to be
+ achieved. This may happen on Linux when using libaio and not setting
+ :option:`direct`\=1, since buffered I/O is not async on that OS. Keep an
+ eye on the I/O depth distribution in the fio output to verify that the
+ achieved depth is as expected. Default: 1.
+
+.. option:: iodepth_batch_submit=int, iodepth_batch=int
+
+ This defines how many pieces of I/O to submit at once. It defaults to 1
+ which means that we submit each I/O as soon as it is available, but can be
+ raised to submit bigger batches of I/O at the time. If it is set to 0 the
+ :option:`iodepth` value will be used.
+
+.. option:: iodepth_batch_complete_min=int, iodepth_batch_complete=int
+
+ This defines how many pieces of I/O to retrieve at once. It defaults to 1
+ which means that we'll ask for a minimum of 1 I/O in the retrieval process
+ from the kernel. The I/O retrieval will go on until we hit the limit set by
+ :option:`iodepth_low`. If this variable is set to 0, then fio will always
+ check for completed events before queuing more I/O. This helps reduce I/O
+ latency, at the cost of more retrieval system calls.
+
+.. option:: iodepth_batch_complete_max=int
+
+ This defines maximum pieces of I/O to retrieve at once. This variable should
+ be used along with :option:`iodepth_batch_complete_min`\=int variable,
+ specifying the range of min and max amount of I/O which should be
+ retrieved. By default it is equal to the :option:`iodepth_batch_complete_min`
+ value.
+
+ Example #1::
+
+ iodepth_batch_complete_min=1
+ iodepth_batch_complete_max=<iodepth>
+
+ which means that we will retrieve at least 1 I/O and up to the whole
+ submitted queue depth. If none of I/O has been completed yet, we will wait.
+
+ Example #2::
+
+ iodepth_batch_complete_min=0
+ iodepth_batch_complete_max=<iodepth>
+
+ which means that we can retrieve up to the whole submitted queue depth, but
+ if none of I/O has been completed yet, we will NOT wait and immediately exit
+ the system call. In this example we simply do polling.
+
+.. option:: iodepth_low=int
+
+ The low water mark indicating when to start filling the queue
+ again. Defaults to the same as :option:`iodepth`, meaning that fio will
+ attempt to keep the queue full at all times. If :option:`iodepth` is set to
+ e.g. 16 and *iodepth_low* is set to 4, then after fio has filled the queue of
+ 16 requests, it will let the depth drain down to 4 before starting to fill
+ it again.
+
+.. option:: io_submit_mode=str
+
+ This option controls how fio submits the I/O to the I/O engine. The default
+ is `inline`, which means that the fio job threads submit and reap I/O
+ directly. If set to `offload`, the job threads will offload I/O submission
+ to a dedicated pool of I/O threads. This requires some coordination and thus
+ has a bit of extra overhead, especially for lower queue depth I/O where it
+ can increase latencies. The benefit is that fio can manage submission rates
+ independently of the device completion rates. This avoids skewed latency
+ reporting if I/O gets backed up on the device side (the coordinated omission
+ problem).
+
+
+I/O rate
+~~~~~~~~
+
+.. option:: thinktime=time
+
+ Stall the job for the specified period of time after an I/O has completed before issuing the
+ next. May be used to simulate processing being done by an application.
+ When the unit is omitted, the value is interpreted in microseconds. See
+ :option:`thinktime_blocks` and :option:`thinktime_spin`.
+
+.. option:: thinktime_spin=time
+
+ Only valid if :option:`thinktime` is set - pretend to spend CPU time doing
+ something with the data received, before falling back to sleeping for the
+ rest of the period specified by :option:`thinktime`. When the unit is
+ omitted, the value is interpreted in microseconds.
+
+.. option:: thinktime_blocks=int
+
+ Only valid if :option:`thinktime` is set - control how many blocks to issue,
+ before waiting `thinktime` usecs. If not set, defaults to 1 which will make
+ fio wait `thinktime` usecs after every block. This effectively makes any
+ queue depth setting redundant, since no more than 1 I/O will be queued
+ before we have to complete it and do our thinktime. In other words, this
+ setting effectively caps the queue depth if the latter is larger.
+
+.. option:: rate=int[,int][,int]
+
+ Cap the bandwidth used by this job. The number is in bytes/sec, the normal
+ suffix rules apply. Comma-separated values may be specified for reads,
+ writes, and trims as described in :option:`blocksize`.
+
+ For example, using `rate=1m,500k` would limit reads to 1MiB/sec and writes to
+ 500KiB/sec. Capping only reads or writes can be done with `rate=,500k` or
+ `rate=500k,` where the former will only limit writes (to 500KiB/sec) and the
+ latter will only limit reads.
+
+.. option:: rate_min=int[,int][,int]
+
+ Tell fio to do whatever it can to maintain at least this bandwidth. Failing
+ to meet this requirement will cause the job to exit. Comma-separated values
+ may be specified for reads, writes, and trims as described in
+ :option:`blocksize`.
+
+.. option:: rate_iops=int[,int][,int]
+
+ Cap the bandwidth to this number of IOPS. Basically the same as
+ :option:`rate`, just specified independently of bandwidth. If the job is
+ given a block size range instead of a fixed value, the smallest block size
+ is used as the metric. Comma-separated values may be specified for reads,
+ writes, and trims as described in :option:`blocksize`.
+
+.. option:: rate_iops_min=int[,int][,int]
+
+ If fio doesn't meet this rate of I/O, it will cause the job to exit.
+ Comma-separated values may be specified for reads, writes, and trims as
+ described in :option:`blocksize`.
+
+.. option:: rate_process=str
+
+ This option controls how fio manages rated I/O submissions. The default is
+ `linear`, which submits I/O in a linear fashion with fixed delays between
+ I/Os that gets adjusted based on I/O completion rates. If this is set to
+ `poisson`, fio will submit I/O based on a more real world random request
+ flow, known as the Poisson process
+ (https://en.wikipedia.org/wiki/Poisson_point_process). The lambda will be
+ 10^6 / IOPS for the given workload.
+
+
+I/O latency
+~~~~~~~~~~~
+
+.. option:: latency_target=time
+
+ If set, fio will attempt to find the max performance point that the given
+ workload will run at while maintaining a latency below this target. When
+ the unit is omitted, the value is interpreted in microseconds. See
+ :option:`latency_window` and :option:`latency_percentile`.
+
+.. option:: latency_window=time
+
+ Used with :option:`latency_target` to specify the sample window that the job
+ is run at varying queue depths to test the performance. When the unit is
+ omitted, the value is interpreted in microseconds.
+
+.. option:: latency_percentile=float
+
+ The percentage of I/Os that must fall within the criteria specified by
+ :option:`latency_target` and :option:`latency_window`. If not set, this
+ defaults to 100.0, meaning that all I/Os must be equal or below to the value
+ set by :option:`latency_target`.
+
+.. option:: max_latency=time
+
+ If set, fio will exit the job with an ETIMEDOUT error if it exceeds this
+ maximum latency. When the unit is omitted, the value is interpreted in
+ microseconds.
+
+.. option:: rate_cycle=int
+
+ Average bandwidth for :option:`rate` and :option:`rate_min` over this number
+ of milliseconds. Defaults to 1000.
+
+
+I/O replay
+~~~~~~~~~~
+
+.. option:: write_iolog=str
+
+ Write the issued I/O patterns to the specified file. See
+ :option:`read_iolog`. Specify a separate file for each job, otherwise the
+ iologs will be interspersed and the file may be corrupt.
+
+.. option:: read_iolog=str
+
+ Open an iolog with the specified filename and replay the I/O patterns it
+ contains. This can be used to store a workload and replay it sometime
+ later. The iolog given may also be a blktrace binary file, which allows fio
+ to replay a workload captured by :command:`blktrace`. See
+ :manpage:`blktrace(8)` for how to capture such logging data. For blktrace
+ replay, the file needs to be turned into a blkparse binary data file first
+ (``blkparse <device> -o /dev/null -d file_for_fio.bin``).
+
+.. option:: replay_no_stall=int
+
+ When replaying I/O with :option:`read_iolog` the default behavior is to
+ attempt to respect the timestamps within the log and replay them with the
+ appropriate delay between IOPS. By setting this variable fio will not
+ respect the timestamps and attempt to replay them as fast as possible while
+ still respecting ordering. The result is the same I/O pattern to a given
+ device, but different timings.
+
+.. option:: replay_redirect=str
+
+ While replaying I/O patterns using :option:`read_iolog` the default behavior
+ is to replay the IOPS onto the major/minor device that each IOP was recorded
+ from. This is sometimes undesirable because on a different machine those
+ major/minor numbers can map to a different device. Changing hardware on the
+ same system can also result in a different major/minor mapping.
+ ``replay_redirect`` causes all I/Os to be replayed onto the single specified
+ device regardless of the device it was recorded
+ from. i.e. :option:`replay_redirect`\= :file:`/dev/sdc` would cause all I/O
+ in the blktrace or iolog to be replayed onto :file:`/dev/sdc`. This means
+ multiple devices will be replayed onto a single device, if the trace
+ contains multiple devices. If you want multiple devices to be replayed
+ concurrently to multiple redirected devices you must blkparse your trace
+ into separate traces and replay them with independent fio invocations.
+ Unfortunately this also breaks the strict time ordering between multiple
+ device accesses.
+
+.. option:: replay_align=int
+
+ Force alignment of I/O offsets and lengths in a trace to this power of 2
+ value.
+
+.. option:: replay_scale=int
+
+ Scale sector offsets down by this factor when replaying traces.
+
+
+Threads, processes and job synchronization
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. option:: thread
+
+ Fio defaults to creating jobs by using fork, however if this option is
+ given, fio will create jobs by using POSIX Threads' function
+ :manpage:`pthread_create(3)` to create threads instead.
+
+.. option:: wait_for=str
+
+ If set, the current job won't be started until all workers of the specified
+ waitee job are done.
+
+ ``wait_for`` operates on the job name basis, so there are a few
+ limitations. First, the waitee must be defined prior to the waiter job
+ (meaning no forward references). Second, if a job is being referenced as a
+ waitee, it must have a unique name (no duplicate waitees).
+
+.. option:: nice=int
+
+ Run the job with the given nice value. See man :manpage:`nice(2)`.
+
+ On Windows, values less than -15 set the process class to "High"; -1 through
+ -15 set "Above Normal"; 1 through 15 "Below Normal"; and above 15 "Idle"
+ priority class.
+
+.. option:: prio=int
+
+ Set the I/O priority value of this job. Linux limits us to a positive value
+ between 0 and 7, with 0 being the highest. See man
+ :manpage:`ionice(1)`. Refer to an appropriate manpage for other operating
+ systems since meaning of priority may differ.
+
+.. option:: prioclass=int
+
+ Set the I/O priority class. See man :manpage:`ionice(1)`.
+
+.. option:: cpumask=int
+
+ Set the CPU affinity of this job. The parameter given is a bit mask of
+ allowed CPUs the job may run on. So if you want the allowed CPUs to be 1
+ and 5, you would pass the decimal value of (1 << 1 | 1 << 5), or 34. See man
+ :manpage:`sched_setaffinity(2)`. This may not work on all supported
+ operating systems or kernel versions. This option doesn't work well for a
+ higher CPU count than what you can store in an integer mask, so it can only
+ control cpus 1-32. For boxes with larger CPU counts, use
+ :option:`cpus_allowed`.
+
+.. option:: cpus_allowed=str
+
+ Controls the same options as :option:`cpumask`, but accepts a textual
+ specification of the permitted CPUs instead. So to use CPUs 1 and 5 you
+ would specify ``cpus_allowed=1,5``. This option also allows a range of CPUs
+ to be specified -- say you wanted a binding to CPUs 1, 5, and 8 to 15, you
+ would set ``cpus_allowed=1,5,8-15``.
+
+.. option:: cpus_allowed_policy=str
+
+ Set the policy of how fio distributes the CPUs specified by
+ :option:`cpus_allowed` or :option:`cpumask`. Two policies are supported:
+
+ **shared**
+ All jobs will share the CPU set specified.
+ **split**
+ Each job will get a unique CPU from the CPU set.
+
+ **shared** is the default behavior, if the option isn't specified. If
+ **split** is specified, then fio will will assign one cpu per job. If not
+ enough CPUs are given for the jobs listed, then fio will roundrobin the CPUs
+ in the set.
+
+.. option:: numa_cpu_nodes=str
+
+ Set this job running on specified NUMA nodes' CPUs. The arguments allow
+ comma delimited list of cpu numbers, A-B ranges, or `all`. Note, to enable
+ NUMA options support, fio must be built on a system with libnuma-dev(el)
+ installed.
+
+.. option:: numa_mem_policy=str
+
+ Set this job's memory policy and corresponding NUMA nodes. Format of the
+ arguments::
+
+ <mode>[:<nodelist>]
+
+ ``mode`` is one of the following memory poicies: ``default``, ``prefer``,
+ ``bind``, ``interleave`` or ``local``. For ``default`` and ``local`` memory
+ policies, no node needs to be specified. For ``prefer``, only one node is
+ allowed. For ``bind`` and ``interleave`` the ``nodelist`` may be as
+ follows: a comma delimited list of numbers, A-B ranges, or `all`.
+
+.. option:: cgroup=str
+
+ Add job to this control group. If it doesn't exist, it will be created. The
+ system must have a mounted cgroup blkio mount point for this to work. If
+ your system doesn't have it mounted, you can do so with::
+
+ # mount -t cgroup -o blkio none /cgroup
+
+.. option:: cgroup_weight=int
+
+ Set the weight of the cgroup to this value. See the documentation that comes
+ with the kernel, allowed values are in the range of 100..1000.
+
+.. option:: cgroup_nodelete=bool
+
+ Normally fio will delete the cgroups it has created after the job
+ completion. To override this behavior and to leave cgroups around after the
+ job completion, set ``cgroup_nodelete=1``. This can be useful if one wants
+ to inspect various cgroup files after job completion. Default: false.
+
+.. option:: flow_id=int
+
+ The ID of the flow. If not specified, it defaults to being a global
+ flow. See :option:`flow`.
+
+.. option:: flow=int
+
+ Weight in token-based flow control. If this value is used, then there is a
+ 'flow counter' which is used to regulate the proportion of activity between
+ two or more jobs. Fio attempts to keep this flow counter near zero. The
+ ``flow`` parameter stands for how much should be added or subtracted to the
+ flow counter on each iteration of the main I/O loop. That is, if one job has
+ ``flow=8`` and another job has ``flow=-1``, then there will be a roughly 1:8
+ ratio in how much one runs vs the other.
+
+.. option:: flow_watermark=int
+
+ The maximum value that the absolute value of the flow counter is allowed to
+ reach before the job must wait for a lower value of the counter.
+
+.. option:: flow_sleep=int
+
+ The period of time, in microseconds, to wait after the flow watermark has
+ been exceeded before retrying operations.
+
+.. option:: stonewall, wait_for_previous
+
+ Wait for preceding jobs in the job file to exit, before starting this
+ one. Can be used to insert serialization points in the job file. A stone
+ wall also implies starting a new reporting group, see
+ :option:`group_reporting`.
+
+.. option:: exitall
+
+ By default, fio will continue running all other jobs when one job finishes
+ but sometimes this is not the desired action. Setting ``exitall`` will
+ instead make fio terminate all other jobs when one job finishes.
+
+.. option:: exec_prerun=str
+
+ Before running this job, issue the command specified through
+ :manpage:`system(3)`. Output is redirected in a file called
+ :file:`jobname.prerun.txt`.
+
+.. option:: exec_postrun=str
+
+ After the job completes, issue the command specified though
+ :manpage:`system(3)`. Output is redirected in a file called
+ :file:`jobname.postrun.txt`.
+
+.. option:: uid=int
+
+ Instead of running as the invoking user, set the user ID to this value
+ before the thread/process does any work.
+
+.. option:: gid=int
+
+ Set group ID, see :option:`uid`.
+
+
+Verification
+~~~~~~~~~~~~
+
+.. option:: verify_only
+
+ Do not perform specified workload, only verify data still matches previous
+ invocation of this workload. This option allows one to check data multiple
+ times at a later date without overwriting it. This option makes sense only
+ for workloads that write data, and does not support workloads with the
+ :option:`time_based` option set.
+
+.. option:: do_verify=bool
+
+ Run the verify phase after a write phase. Only valid if :option:`verify` is
+ set. Default: true.
+
+.. option:: verify=str
+
+ If writing to a file, fio can verify the file contents after each iteration
+ of the job. Each verification method also implies verification of special
+ header, which is written to the beginning of each block. This header also
+ includes meta information, like offset of the block, block number, timestamp
+ when block was written, etc. :option:`verify` can be combined with
+ :option:`verify_pattern` option. The allowed values are:
+
+ **md5**
+ Use an md5 sum of the data area and store it in the header of
+ each block.
+
+ **crc64**
+ Use an experimental crc64 sum of the data area and store it in the
+ header of each block.
+
+ **crc32c**
+ Use a crc32c sum of the data area and store it in the header of
+ each block. This will automatically use hardware acceleration
+ (e.g. SSE4.2 on an x86 or CRC crypto extensions on ARM64) but will
+ fall back to software crc32c if none is found. Generally the
+ fatest checksum fio supports when hardware accelerated.
+
+ **crc32c-intel**
+ Synonym for crc32c.
+
+ **crc32**
+ Use a crc32 sum of the data area and store it in the header of each
+ block.
+
+ **crc16**
+ Use a crc16 sum of the data area and store it in the header of each
+ block.
+
+ **crc7**
+ Use a crc7 sum of the data area and store it in the header of each
+ block.
+
+ **xxhash**
+ Use xxhash as the checksum function. Generally the fastest software
+ checksum that fio supports.
+
+ **sha512**
+ Use sha512 as the checksum function.
+
+ **sha256**
+ Use sha256 as the checksum function.
+
+ **sha1**
+ Use optimized sha1 as the checksum function.
+
+ **sha3-224**
+ Use optimized sha3-224 as the checksum function.
+
+ **sha3-256**
+ Use optimized sha3-256 as the checksum function.
+
+ **sha3-384**
+ Use optimized sha3-384 as the checksum function.
+
+ **sha3-512**
+ Use optimized sha3-512 as the checksum function.
+
+ **meta**
+ This option is deprecated, since now meta information is included in
+ generic verification header and meta verification happens by
+ default. For detailed information see the description of the
+ :option:`verify` setting. This option is kept because of
+ compatibility's sake with old configurations. Do not use it.
+
+ **pattern**
+ Verify a strict pattern. Normally fio includes a header with some
+ basic information and checksumming, but if this option is set, only
+ the specific pattern set with :option:`verify_pattern` is verified.
+
+ **null**
+ Only pretend to verify. Useful for testing internals with
+ :option:`ioengine`\=null, not for much else.
+
+ This option can be used for repeated burn-in tests of a system to make sure
+ that the written data is also correctly read back. If the data direction
+ given is a read or random read, fio will assume that it should verify a
+ previously written file. If the data direction includes any form of write,
+ the verify will be of the newly written data.
+
+.. option:: verifysort=bool
+
+ If true, fio will sort written verify blocks when it deems it faster to read
+ them back in a sorted manner. This is often the case when overwriting an
+ existing file, since the blocks are already laid out in the file system. You
+ can ignore this option unless doing huge amounts of really fast I/O where
+ the red-black tree sorting CPU time becomes significant. Default: true.
+
+.. option:: verifysort_nr=int
+
+ Pre-load and sort verify blocks for a read workload.
+
+.. option:: verify_offset=int
+
+ Swap the verification header with data somewhere else in the block before
+ writing. It is swapped back before verifying.
+
+.. option:: verify_interval=int
+
+ Write the verification header at a finer granularity than the
+ :option:`blocksize`. It will be written for chunks the size of
+ ``verify_interval``. :option:`blocksize` should divide this evenly.
+
+.. option:: verify_pattern=str
+
+ If set, fio will fill the I/O buffers with this pattern. Fio defaults to
+ filling with totally random bytes, but sometimes it's interesting to fill
+ with a known pattern for I/O verification purposes. Depending on the width
+ of the pattern, fio will fill 1/2/3/4 bytes of the buffer at the time (it can
+ be either a decimal or a hex number). The ``verify_pattern`` if larger than
+ a 32-bit quantity has to be a hex number that starts with either "0x" or
+ "0X". Use with :option:`verify`. Also, ``verify_pattern`` supports %o
+ format, which means that for each block offset will be written and then
+ verified back, e.g.::
+
+ verify_pattern=%o
+
+ Or use combination of everything::
+
+ verify_pattern=0xff%o"abcd"-12
+
+.. option:: verify_fatal=bool
+
+ Normally fio will keep checking the entire contents before quitting on a
+ block verification failure. If this option is set, fio will exit the job on
+ the first observed failure. Default: false.
+
+.. option:: verify_dump=bool
+
+ If set, dump the contents of both the original data block and the data block
+ we read off disk to files. This allows later analysis to inspect just what
+ kind of data corruption occurred. Off by default.
+
+.. option:: verify_async=int
+
+ Fio will normally verify I/O inline from the submitting thread. This option
+ takes an integer describing how many async offload threads to create for I/O
+ verification instead, causing fio to offload the duty of verifying I/O
+ contents to one or more separate threads. If using this offload option, even
+ sync I/O engines can benefit from using an :option:`iodepth` setting higher
+ than 1, as it allows them to have I/O in flight while verifies are running.
+ Defaults to 0 async threads, i.e. verification is not asynchronous.
+
+.. option:: verify_async_cpus=str
+
+ Tell fio to set the given CPU affinity on the async I/O verification
+ threads. See :option:`cpus_allowed` for the format used.
+
+.. option:: verify_backlog=int
+
+ Fio will normally verify the written contents of a job that utilizes verify
+ once that job has completed. In other words, everything is written then
+ everything is read back and verified. You may want to verify continually
+ instead for a variety of reasons. Fio stores the meta data associated with
+ an I/O block in memory, so for large verify workloads, quite a bit of memory
+ would be used up holding this meta data. If this option is enabled, fio will
+ write only N blocks before verifying these blocks.
+
+.. option:: verify_backlog_batch=int
+
+ Control how many blocks fio will verify if :option:`verify_backlog` is
+ set. If not set, will default to the value of :option:`verify_backlog`
+ (meaning the entire queue is read back and verified). If
+ ``verify_backlog_batch`` is less than :option:`verify_backlog` then not all
+ blocks will be verified, if ``verify_backlog_batch`` is larger than
+ :option:`verify_backlog`, some blocks will be verified more than once.
+
+.. option:: verify_state_save=bool
+
+ When a job exits during the write phase of a verify workload, save its
+ current state. This allows fio to replay up until that point, if the verify
+ state is loaded for the verify read phase. The format of the filename is,
+ roughly::
+
+ <type>-<jobname>-<jobindex>-verify.state.
+
+ <type> is "local" for a local run, "sock" for a client/server socket
+ connection, and "ip" (192.168.0.1, for instance) for a networked
+ client/server connection. Defaults to true.
+
+.. option:: verify_state_load=bool
+
+ If a verify termination trigger was used, fio stores the current write state
+ of each thread. This can be used at verification time so that fio knows how
+ far it should verify. Without this information, fio will run a full
+ verification pass, according to the settings in the job file used. Default
+ false.
+
+.. option:: trim_percentage=int
+
+ Number of verify blocks to discard/trim.
+
+.. option:: trim_verify_zero=bool
+
+ Verify that trim/discarded blocks are returned as zeros.
+
+.. option:: trim_backlog=int
+
+ Verify that trim/discarded blocks are returned as zeros.
+
+.. option:: trim_backlog_batch=int
+
+ Trim this number of I/O blocks.
+
+.. option:: experimental_verify=bool
+
+ Enable experimental verification.
+
+
+Steady state
+~~~~~~~~~~~~
+
+.. option:: steadystate=str:float, ss=str:float
+
+ Define the criterion and limit for assessing steady state performance. The
+ first parameter designates the criterion whereas the second parameter sets
+ the threshold. When the criterion falls below the threshold for the
+ specified duration, the job will stop. For example, `iops_slope:0.1%` will
+ direct fio to terminate the job when the least squares regression slope
+ falls below 0.1% of the mean IOPS. If :option:`group_reporting` is enabled
+ this will apply to all jobs in the group. Below is the list of available
+ steady state assessment criteria. All assessments are carried out using only
+ data from the rolling collection window. Threshold limits can be expressed
+ as a fixed value or as a percentage of the mean in the collection window.
+
+ **iops**
+ Collect IOPS data. Stop the job if all individual IOPS measurements
+ are within the specified limit of the mean IOPS (e.g., ``iops:2``
+ means that all individual IOPS values must be within 2 of the mean,
+ whereas ``iops:0.2%`` means that all individual IOPS values must be
+ within 0.2% of the mean IOPS to terminate the job).
+
+ **iops_slope**
+ Collect IOPS data and calculate the least squares regression
+ slope. Stop the job if the slope falls below the specified limit.
+
+ **bw**
+ Collect bandwidth data. Stop the job if all individual bandwidth
+ measurements are within the specified limit of the mean bandwidth.
+
+ **bw_slope**
+ Collect bandwidth data and calculate the least squares regression
+ slope. Stop the job if the slope falls below the specified limit.
+
+.. option:: steadystate_duration=time, ss_dur=time
+
+ A rolling window of this duration will be used to judge whether steady state
+ has been reached. Data will be collected once per second. The default is 0
+ which disables steady state detection. When the unit is omitted, the
+ value is interpreted in seconds.
+
+.. option:: steadystate_ramp_time=time, ss_ramp=time
+
+ Allow the job to run for the specified duration before beginning data
+ collection for checking the steady state job termination criterion. The
+ default is 0. When the unit is omitted, the value is interpreted in seconds.
+
+
+Measurements and reporting
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. option:: per_job_logs=bool
+
+ If set, this generates bw/clat/iops log with per file private filenames. If
+ not set, jobs with identical names will share the log filename. Default:
+ true.
+
+.. option:: group_reporting
+
+ It may sometimes be interesting to display statistics for groups of jobs as
+ a whole instead of for each individual job. This is especially true if
+ :option:`numjobs` is used; looking at individual thread/process output
+ quickly becomes unwieldy. To see the final report per-group instead of
+ per-job, use :option:`group_reporting`. Jobs in a file will be part of the
+ same reporting group, unless if separated by a :option:`stonewall`, or by
+ using :option:`new_group`.
+
+.. option:: new_group
+
+ Start a new reporting group. See: :option:`group_reporting`. If not given,
+ all jobs in a file will be part of the same reporting group, unless
+ separated by a :option:`stonewall`.
+
+.. option:: stats
+
+ By default, fio collects and shows final output results for all jobs
+ that run. If this option is set to 0, then fio will ignore it in
+ the final stat output.
+
+.. option:: write_bw_log=str
+
+ If given, write a bandwidth log for this job. Can be used to store data of
+ the bandwidth of the jobs in their lifetime. The included
+ :command:`fio_generate_plots` script uses :command:`gnuplot` to turn these
+ text files into nice graphs. See :option:`write_lat_log` for behavior of
+ given filename. For this option, the postfix is :file:`_bw.x.log`, where `x`
+ is the index of the job (`1..N`, where `N` is the number of jobs). If
+ :option:`per_job_logs` is false, then the filename will not include the job
+ index. See `Log File Formats`_.
+
+.. option:: write_lat_log=str
+
+ Same as :option:`write_bw_log`, except that this option stores I/O
+ submission, completion, and total latencies instead. If no filename is given
+ with this option, the default filename of :file:`jobname_type.log` is
+ used. Even if the filename is given, fio will still append the type of
+ log. So if one specifies::
+
+ write_lat_log=foo
+
+ The actual log names will be :file:`foo_slat.x.log`, :file:`foo_clat.x.log`,
+ and :file:`foo_lat.x.log`, where `x` is the index of the job (1..N, where N
+ is the number of jobs). This helps :command:`fio_generate_plot` find the
+ logs automatically. If :option:`per_job_logs` is false, then the filename
+ will not include the job index. See `Log File Formats`_.
+
+.. option:: write_hist_log=str
+
+ Same as :option:`write_lat_log`, but writes I/O completion latency
+ histograms. If no filename is given with this option, the default filename
+ of :file:`jobname_clat_hist.x.log` is used, where `x` is the index of the
+ job (1..N, where `N` is the number of jobs). Even if the filename is given,
+ fio will still append the type of log. If :option:`per_job_logs` is false,
+ then the filename will not include the job index. See `Log File Formats`_.
+
+.. option:: write_iops_log=str
+
+ Same as :option:`write_bw_log`, but writes IOPS. If no filename is given
+ with this option, the default filename of :file:`jobname_type.x.log` is
+ used,where `x` is the index of the job (1..N, where `N` is the number of
+ jobs). Even if the filename is given, fio will still append the type of
+ log. If :option:`per_job_logs` is false, then the filename will not include
+ the job index. See `Log File Formats`_.
+
+.. option:: log_avg_msec=int
+
+ By default, fio will log an entry in the iops, latency, or bw log for every
+ I/O that completes. When writing to the disk log, that can quickly grow to a
+ very large size. Setting this option makes fio average the each log entry
+ over the specified period of time, reducing the resolution of the log. See
+ :option:`log_max_value` as well. Defaults to 0, logging all entries.
+ Also see `Log File Formats`_.
+
+.. option:: log_hist_msec=int
+
+ Same as :option:`log_avg_msec`, but logs entries for completion latency
+ histograms. Computing latency percentiles from averages of intervals using
+ :option:`log_avg_msec` is inaccurate. Setting this option makes fio log
+ histogram entries over the specified period of time, reducing log sizes for
+ high IOPS devices while retaining percentile accuracy. See
+ :option:`log_hist_coarseness` as well. Defaults to 0, meaning histogram
+ logging is disabled.
+
+.. option:: log_hist_coarseness=int
+
+ Integer ranging from 0 to 6, defining the coarseness of the resolution of
+ the histogram logs enabled with :option:`log_hist_msec`. For each increment
+ in coarseness, fio outputs half as many bins. Defaults to 0, for which
+ histogram logs contain 1216 latency bins. See `Log File Formats`_.
+
+.. option:: log_max_value=bool
+
+ If :option:`log_avg_msec` is set, fio logs the average over that window. If
+ you instead want to log the maximum value, set this option to 1. Defaults to
+ 0, meaning that averaged values are logged.
+
+.. option:: log_offset=int
+
+ If this is set, the iolog options will include the byte offset for the I/O
+ entry as well as the other data values.
+
+.. option:: log_compression=int
+
+ If this is set, fio will compress the I/O logs as it goes, to keep the
+ memory footprint lower. When a log reaches the specified size, that chunk is
+ removed and compressed in the background. Given that I/O logs are fairly
+ highly compressible, this yields a nice memory savings for longer runs. The
+ downside is that the compression will consume some background CPU cycles, so
+ it may impact the run. This, however, is also true if the logging ends up
+ consuming most of the system memory. So pick your poison. The I/O logs are
+ saved normally at the end of a run, by decompressing the chunks and storing
+ them in the specified log file. This feature depends on the availability of
+ zlib.
+
+.. option:: log_compression_cpus=str
+
+ Define the set of CPUs that are allowed to handle online log compression for
+ the I/O jobs. This can provide better isolation between performance
+ sensitive jobs, and background compression work.
+
+.. option:: log_store_compressed=bool
+
+ If set, fio will store the log files in a compressed format. They can be
+ decompressed with fio, using the :option:`--inflate-log` command line
+ parameter. The files will be stored with a :file:`.fz` suffix.
+
+.. option:: log_unix_epoch=bool
+
+ If set, fio will log Unix timestamps to the log files produced by enabling
+ write_type_log for each log type, instead of the default zero-based
+ timestamps.
+
+.. option:: block_error_percentiles=bool
+
+ If set, record errors in trim block-sized units from writes and trims and
+ output a histogram of how many trims it took to get to errors, and what kind
+ of error was encountered.
+
+.. option:: bwavgtime=int
+
+ Average the calculated bandwidth over the given time. Value is specified in
+ milliseconds. If the job also does bandwidth logging through
+ :option:`write_bw_log`, then the minimum of this option and
+ :option:`log_avg_msec` will be used. Default: 500ms.
+
+.. option:: iopsavgtime=int
+
+ Average the calculated IOPS over the given time. Value is specified in
+ milliseconds. If the job also does IOPS logging through
+ :option:`write_iops_log`, then the minimum of this option and
+ :option:`log_avg_msec` will be used. Default: 500ms.
+
+.. option:: disk_util=bool
+
+ Generate disk utilization statistics, if the platform supports it.
+ Default: true.
+
+.. option:: disable_lat=bool
+
+ Disable measurements of total latency numbers. Useful only for cutting back
+ the number of calls to :manpage:`gettimeofday(2)`, as that does impact
+ performance at really high IOPS rates. Note that to really get rid of a
+ large amount of these calls, this option must be used with
+ :option:`disable_slat` and :option:`disable_bw_measurement` as well.
+
+.. option:: disable_clat=bool
+
+ Disable measurements of completion latency numbers. See
+ :option:`disable_lat`.
+
+.. option:: disable_slat=bool
+
+ Disable measurements of submission latency numbers. See
+ :option:`disable_slat`.
+
+.. option:: disable_bw_measurement=bool, disable_bw=bool
+
+ Disable measurements of throughput/bandwidth numbers. See
+ :option:`disable_lat`.
+
+.. option:: clat_percentiles=bool
+
+ Enable the reporting of percentiles of completion latencies.
+
+.. option:: percentile_list=float_list
+
+ Overwrite the default list of percentiles for completion latencies and the
+ block error histogram. Each number is a floating number in the range
+ (0,100], and the maximum length of the list is 20. Use ``:`` to separate the
+ numbers, and list the numbers in ascending order. For example,
+ ``--percentile_list=99.5:99.9`` will cause fio to report the values of
+ completion latency below which 99.5% and 99.9% of the observed latencies
+ fell, respectively.
+
+
+Error handling
+~~~~~~~~~~~~~~
+
+.. option:: exitall_on_error
+
+ When one job finishes in error, terminate the rest. The default is to wait
+ for each job to finish.
+
+.. option:: continue_on_error=str
+
+ Normally fio will exit the job on the first observed failure. If this option
+ is set, fio will continue the job when there is a 'non-fatal error' (EIO or
+ EILSEQ) until the runtime is exceeded or the I/O size specified is
+ completed. If this option is used, there are two more stats that are
+ appended, the total error count and the first error. The error field given
+ in the stats is the first error that was hit during the run.
+
+ The allowed values are:
+
+ **none**
+ Exit on any I/O or verify errors.
+
+ **read**
+ Continue on read errors, exit on all others.
+
+ **write**
+ Continue on write errors, exit on all others.
+
+ **io**
+ Continue on any I/O error, exit on all others.
+
+ **verify**
+ Continue on verify errors, exit on all others.
+
+ **all**
+ Continue on all errors.
+
+ **0**
+ Backward-compatible alias for 'none'.
+
+ **1**
+ Backward-compatible alias for 'all'.
+
+.. option:: ignore_error=str
+
+ Sometimes you want to ignore some errors during test in that case you can
+ specify error list for each error type, instead of only being able to
+ ignore the default 'non-fatal error' using :option:`continue_on_error`.
+ ``ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST`` errors for
+ given error type is separated with ':'. Error may be symbol ('ENOSPC',
+ 'ENOMEM') or integer. Example::
+
+ ignore_error=EAGAIN,ENOSPC:122
+
+ This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from
+ WRITE. This option works by overriding :option:`continue_on_error` with
+ the list of errors for each error type if any.
+
+.. option:: error_dump=bool
+
+ If set dump every error even if it is non fatal, true by default. If
+ disabled only fatal error will be dumped.
+
+Running predefined workloads
+----------------------------
+
+Fio includes predefined profiles that mimic the I/O workloads generated by
+other tools.
+
+.. option:: profile=str
+
+ The predefined workload to run. Current profiles are:
+
+ **tiobench**
+ Threaded I/O bench (tiotest/tiobench) like workload.
+
+ **act**
+ Aerospike Certification Tool (ACT) like workload.
+
+To view a profile's additional options use :option:`--cmdhelp` after specifying
+the profile. For example::
+
+$ fio --profile=act --cmdhelp
+
+Act profile options
+~~~~~~~~~~~~~~~~~~~
+
+.. option:: device-names=str
+ :noindex:
+
+ Devices to use.
+
+.. option:: load=int
+ :noindex:
+
+ ACT load multiplier. Default: 1.
+
+.. option:: test-duration=time
+ :noindex:
+
+ How long the entire test takes to run. When the unit is omitted, the value
+ is given in seconds. Default: 24h.
+
+.. option:: threads-per-queue=int
+ :noindex:
+
+ Number of read IO threads per device. Default: 8.
+
+.. option:: read-req-num-512-blocks=int
+ :noindex:
+
+ Number of 512B blocks to read at the time. Default: 3.
+
+.. option:: large-block-op-kbytes=int
+ :noindex:
+
+ Size of large block ops in KiB (writes). Default: 131072.
+
+.. option:: prep
+ :noindex:
+
+ Set to run ACT prep phase.
+
+Tiobench profile options
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. option:: size=str
+ :noindex:
+
+ Size in MiB
+
+.. option:: block=int
+ :noindex:
+
+ Block size in bytes. Default: 4096.
+
+.. option:: numruns=int
+ :noindex:
+
+ Number of runs.
+
+.. option:: dir=str
+ :noindex:
+
+ Test directory.
+
+.. option:: threads=int
+ :noindex:
+
+ Number of threads.
+
+Interpreting the output
+-----------------------
+
+..
+ Example output was based on the following:
+ TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --time_based \
+ --rate=1256k --bs=14K --name=quick --runtime=1s --name=mixed \
+ --runtime=2m --rw=rw
+
+Fio spits out a lot of output. While running, fio will display the status of the
+jobs created. An example of that would be::
+
+ Jobs: 1 (f=1): [_(1),M(1)][24.8%][r=20.5MiB/s,w=23.5MiB/s][r=82,w=94 IOPS][eta 01m:31s]
+
+The characters inside the first set of square brackets denote the current status of
+each thread. The first character is the first job defined in the job file, and so
+forth. The possible values (in typical life cycle order) are:
+
++------+-----+-----------------------------------------------------------+
+| Idle | Run | |
++======+=====+===========================================================+
+| P | | Thread setup, but not started. |
++------+-----+-----------------------------------------------------------+
+| C | | Thread created. |
++------+-----+-----------------------------------------------------------+
+| I | | Thread initialized, waiting or generating necessary data. |
++------+-----+-----------------------------------------------------------+
+| | p | Thread running pre-reading file(s). |
++------+-----+-----------------------------------------------------------+
+| | / | Thread is in ramp period. |
++------+-----+-----------------------------------------------------------+
+| | R | Running, doing sequential reads. |
++------+-----+-----------------------------------------------------------+
+| | r | Running, doing random reads. |
++------+-----+-----------------------------------------------------------+
+| | W | Running, doing sequential writes. |
++------+-----+-----------------------------------------------------------+
+| | w | Running, doing random writes. |
++------+-----+-----------------------------------------------------------+
+| | M | Running, doing mixed sequential reads/writes. |
++------+-----+-----------------------------------------------------------+
+| | m | Running, doing mixed random reads/writes. |
++------+-----+-----------------------------------------------------------+
+| | D | Running, doing sequential trims. |
++------+-----+-----------------------------------------------------------+
+| | d | Running, doing random trims. |
++------+-----+-----------------------------------------------------------+
+| | F | Running, currently waiting for :manpage:`fsync(2)`. |
++------+-----+-----------------------------------------------------------+
+| | V | Running, doing verification of written data. |
++------+-----+-----------------------------------------------------------+
+| f | | Thread finishing. |
++------+-----+-----------------------------------------------------------+
+| E | | Thread exited, not reaped by main thread yet. |
++------+-----+-----------------------------------------------------------+
+| _ | | Thread reaped. |
++------+-----+-----------------------------------------------------------+
+| X | | Thread reaped, exited with an error. |
++------+-----+-----------------------------------------------------------+
+| K | | Thread reaped, exited due to signal. |
++------+-----+-----------------------------------------------------------+
+
+..
+ Example output was based on the following:
+ TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --runtime=58m \
+ --time_based --rate=2512k --bs=256K --numjobs=10 \
+ --name=readers --rw=read --name=writers --rw=write
+
+Fio will condense the thread string as not to take up more space on the command
+line than needed. For instance, if you have 10 readers and 10 writers running,
+the output would look like this::
+
+ Jobs: 20 (f=20): [R(10),W(10)][4.0%][r=20.5MiB/s,w=23.5MiB/s][r=82,w=94 IOPS][eta 57m:36s]
+
+Note that the status string is displayed in order, so it's possible to tell which of
+the jobs are currently doing what. In the example above this means that jobs 1--10
+are readers and 11--20 are writers.
+
+The other values are fairly self explanatory -- number of threads currently
+running and doing I/O, the number of currently open files (f=), the estimated
+completion percentage, the rate of I/O since last check (read speed listed first,
+then write speed and optionally trim speed) in terms of bandwidth and IOPS, and time to completion for the current
+running group. It's impossible to estimate runtime of the following groups (if
+any).
+
+..
+ Example output was based on the following:
+ TZ=UTC fio --iodepth=16 --ioengine=posixaio --filename=/tmp/fiofile \
+ --direct=1 --size=100M --time_based --runtime=50s --rate_iops=89 \
+ --bs=7K --name=Client1 --rw=write
+
+When fio is done (or interrupted by :kbd:`Ctrl-C`), it will show the data for
+each thread, group of threads, and disks in that order. For each overall thread (or
+group) the output looks like::
+
+ Client1: (groupid=0, jobs=1): err= 0: pid=16109: Sat Jun 24 12:07:54 2017
+ write: IOPS=88, BW=623KiB/s (638kB/s)(30.4MiB/50032msec)
+ slat (nsec): min=500, max=145500, avg=8318.00, stdev=4781.50
+ clat (usec): min=170, max=78367, avg=4019.02, stdev=8293.31
+ lat (usec): min=174, max=78375, avg=4027.34, stdev=8291.79
+ clat percentiles (usec):
+ | 1.00th=[ 302], 5.00th=[ 326], 10.00th=[ 343], 20.00th=[ 363],
+ | 30.00th=[ 392], 40.00th=[ 404], 50.00th=[ 416], 60.00th=[ 445],
+ | 70.00th=[ 816], 80.00th=[ 6718], 90.00th=[12911], 95.00th=[21627],
+ | 99.00th=[43779], 99.50th=[51643], 99.90th=[68682], 99.95th=[72877],
+ | 99.99th=[78119]
+ bw ( KiB/s): min= 532, max= 686, per=0.10%, avg=622.87, stdev=24.82, samples= 100
+ iops : min= 76, max= 98, avg=88.98, stdev= 3.54, samples= 100
+ lat (usec) : 250=0.04%, 500=64.11%, 750=4.81%, 1000=2.79%
+ lat (msec) : 2=4.16%, 4=1.84%, 10=4.90%, 20=11.33%, 50=5.37%
+ lat (msec) : 100=0.65%
+ cpu : usr=0.27%, sys=0.18%, ctx=12072, majf=0, minf=21
+ IO depths : 1=85.0%, 2=13.1%, 4=1.8%, 8=0.1%, 16=0.0%, 32=0.0%, >=64=0.0%
+ submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
+ complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
+ issued rwt: total=0,4450,0, short=0,0,0, dropped=0,0,0
+ latency : target=0, window=0, percentile=100.00%, depth=8
+
+The job name (or first job's name when using :option:`group_reporting`) is printed,
+along with the group id, count of jobs being aggregated, last error id seen (which
+is 0 when there are no errors), pid/tid of that thread and the time the job/group
+completed. Below are the I/O statistics for each data direction performed (showing
+writes in the example above). In the order listed, they denote:
+
+**read/write/trim**
+ The string before the colon shows the I/O direction the statistics
+ are for. **IOPS** is the average I/Os performed per second. **BW**
+ is the average bandwidth rate shown as: value in power of 2 format
+ (value in power of 10 format). The last two values show: (**total
+ I/O performed** in power of 2 format / **runtime** of that thread).
+
+**slat**
+ Submission latency (**min** being the minimum, **max** being the
+ maximum, **avg** being the average, **stdev** being the standard
+ deviation). This is the time it took to submit the I/O. For
+ sync I/O this row is not displayed as the slat is really the
+ completion latency (since queue/complete is one operation there).
+ This value can be in nanoseconds, microseconds or milliseconds ---
+ fio will choose the most appropriate base and print that (in the
+ example above nanoseconds was the best scale). Note: in :option:`--minimal` mode
+ latencies are always expressed in microseconds.
+
+**clat**
+ Completion latency. Same names as slat, this denotes the time from
+ submission to completion of the I/O pieces. For sync I/O, clat will
+ usually be equal (or very close) to 0, as the time from submit to
+ complete is basically just CPU time (I/O has already been done, see slat
+ explanation).
+
+**bw**
+ Bandwidth statistics based on samples. Same names as the xlat stats,
+ but also includes the number of samples taken (**samples**) and an
+ approximate percentage of total aggregate bandwidth this thread
+ received in its group (**per**). This last value is only really
+ useful if the threads in this group are on the same disk, since they
+ are then competing for disk access.
+
+**iops**
+ IOPS statistics based on samples. Same names as bw.
+
+**cpu**
+ CPU usage. User and system time, along with the number of context
+ switches this thread went through, usage of system and user time, and
+ finally the number of major and minor page faults. The CPU utilization
+ numbers are averages for the jobs in that reporting group, while the
+ context and fault counters are summed.
+
+**IO depths**
+ The distribution of I/O depths over the job lifetime. The numbers are
+ divided into powers of 2 and each entry covers depths from that value
+ up to those that are lower than the next entry -- e.g., 16= covers
+ depths from 16 to 31. Note that the range covered by a depth
+ distribution entry can be different to the range covered by the
+ equivalent submit/complete distribution entry.
+
+**IO submit**
+ How many pieces of I/O were submitting in a single submit call. Each
+ entry denotes that amount and below, until the previous entry -- e.g.,
+ 16=100% means that we submitted anywhere between 9 to 16 I/Os per submit
+ call. Note that the range covered by a submit distribution entry can
+ be different to the range covered by the equivalent depth distribution
+ entry.
+
+**IO complete**
+ Like the above submit number, but for completions instead.
+
+**IO issued rwt**
+ The number of read/write/trim requests issued, and how many of them were
+ short or dropped.
+
+**IO latencies**
+ The distribution of I/O completion latencies. This is the time from when
+ I/O leaves fio and when it gets completed. The numbers follow the same
+ pattern as the I/O depths, meaning that 2=1.6% means that 1.6% of the
+ I/O completed within 2 msecs, 20=12.8% means that 12.8% of the I/O took
+ more than 10 msecs, but less than (or equal to) 20 msecs.
+
+..
+ Example output was based on the following:
+ TZ=UTC fio --ioengine=null --iodepth=2 --size=100M --numjobs=2 \
+ --rate_process=poisson --io_limit=32M --name=read --bs=128k \
+ --rate=11M --name=write --rw=write --bs=2k --rate=700k
+
+After each client has been listed, the group statistics are printed. They
+will look like this::
+
+ Run status group 0 (all jobs):
+ READ: bw=20.9MiB/s (21.9MB/s), 10.4MiB/s-10.8MiB/s (10.9MB/s-11.3MB/s), io=64.0MiB (67.1MB), run=2973-3069msec
+ WRITE: bw=1231KiB/s (1261kB/s), 616KiB/s-621KiB/s (630kB/s-636kB/s), io=64.0MiB (67.1MB), run=52747-53223msec
+
+For each data direction it prints:
+
+**bw**
+ Aggregate bandwidth of threads in this group followed by the
+ minimum and maximum bandwidth of all the threads in this group.
+ Values outside of brackets are power-of-2 format and those
+ within are the equivalent value in a power-of-10 format.
+**io**
+ Aggregate I/O performed of all threads in this group. The
+ format is the same as bw.
+**run**
+ The smallest and longest runtimes of the threads in this group.
+
+And finally, the disk statistics are printed. They will look like this::
+
+ Disk stats (read/write):
+ sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00%
+
+Each value is printed for both reads and writes, with reads first. The
+numbers denote:
+
+**ios**
+ Number of I/Os performed by all groups.
+**merge**
+ Number of merges I/O the I/O scheduler.
+**ticks**
+ Number of ticks we kept the disk busy.
+**in_queue**
+ Total time spent in the disk queue.
+**util**
+ The disk utilization. A value of 100% means we kept the disk
+ busy constantly, 50% would be a disk idling half of the time.
+
+It is also possible to get fio to dump the current output while it is running,
+without terminating the job. To do that, send fio the **USR1** signal. You can
+also get regularly timed dumps by using the :option:`--status-interval`
+parameter, or by creating a file in :file:`/tmp` named
+:file:`fio-dump-status`. If fio sees this file, it will unlink it and dump the
+current output status.
+
+
+Terse output
+------------
+
+For scripted usage where you typically want to generate tables or graphs of the
+results, fio can output the results in a semicolon separated format. The format
+is one long line of values, such as::
+
+ 2;card0;0;0;7139336;121836;60004;1;10109;27.932460;116.933948;220;126861;3495.446807;1085.368601;226;126864;3523.635629;1089.012448;24063;99944;50.275485%;59818.274627;5540.657370;7155060;122104;60004;1;8338;29.086342;117.839068;388;128077;5032.488518;1234.785715;391;128085;5061.839412;1236.909129;23436;100928;50.287926%;59964.832030;5644.844189;14.595833%;19.394167%;123706;0;7313;0.1%;0.1%;0.1%;0.1%;0.1%;0.1%;100.0%;0.00%;0.00%;0.00%;0.00%;0.00%;0.00%;0.01%;0.02%;0.05%;0.16%;6.04%;40.40%;52.68%;0.64%;0.01%;0.00%;0.01%;0.00%;0.00%;0.00%;0.00%;0.00%
+ A description of this job goes here.
+
+The job description (if provided) follows on a second line.
+
+To enable terse output, use the :option:`--minimal` or
+:option:`--output-format`\=terse command line options. The
+first value is the version of the terse output format. If the output has to be
+changed for some reason, this number will be incremented by 1 to signify that
+change.
+
+Split up, the format is as follows (comments in brackets denote when a
+field was introduced or whether its specific to some terse version):
+
+ ::
+
+ terse version, fio version [v3], jobname, groupid, error
+
+ READ status::
+
+ Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
+ Submission latency: min, max, mean, stdev (usec)
+ Completion latency: min, max, mean, stdev (usec)
+ Completion latency percentiles: 20 fields (see below)
+ Total latency: min, max, mean, stdev (usec)
+ Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
+ IOPS [v5]: min, max, mean, stdev, number of samples
+
+ WRITE status:
+
+ ::
+
+ Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
+ Submission latency: min, max, mean, stdev (usec)
+ Completion latency: min, max, mean, stdev (usec)
+ Completion latency percentiles: 20 fields (see below)
+ Total latency: min, max, mean, stdev (usec)
+ Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
+ IOPS [v5]: min, max, mean, stdev, number of samples
+
+ TRIM status [all but version 3]:
+
+ Fields are similar to READ/WRITE status.
+
+ CPU usage::
+
+ user, system, context switches, major faults, minor faults
+
+ I/O depths::
+
+ <=1, 2, 4, 8, 16, 32, >=64
+
+ I/O latencies microseconds::
+
+ <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
+
+ I/O latencies milliseconds::
+
+ <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
+
+ Disk utilization [v3]::
+
+ Disk name, Read ios, write ios,
+ Read merges, write merges,
+ Read ticks, write ticks,
+ Time spent in queue, disk utilization percentage
+
+ Additional Info (dependent on continue_on_error, default off)::
+
+ total # errors, first error code
+
+ Additional Info (dependent on description being set)::
+
+ Text description
+
+Completion latency percentiles can be a grouping of up to 20 sets, so for the
+terse output fio writes all of them. Each field will look like this::
+
+ 1.00%=6112
+
+which is the Xth percentile, and the `usec` latency associated with it.
+
+For disk utilization, all disks used by fio are shown. So for each disk there
+will be a disk utilization section.
+
+Below is a single line containing short names for each of the fields in the
+minimal output v3, separated by semicolons::
+
+terse_version_3;fio_version;jobname;groupid;error;read_kb;read_bandwidth;read_iops;read_runtime_ms;read_slat_min;read_slat_max;read_slat_mean;read_slat_dev;read_clat_min;read_clat_max;read_clat_mean;read_clat_dev;read_clat_pct01;read_clat_pct02;read_clat_pct03;read_clat_pct04;read_clat_pct05;read_clat_pct06;read_clat_pct07;read_clat_pct08;read_clat_pct09;read_clat_pct10;read_clat_pct11;read_clat_pct12;read_clat_pct13;read_clat_pct14;read_clat_pct15;read_clat_pct16;read_clat_pct17;read_clat_pct18;read_clat_pct19;read_clat_pct20;read_tlat_min;read_lat_max;read_lat_mean;read_lat_dev;read_bw_min;read_bw_max;read_bw_agg_pct;read_bw_mean;read_bw_dev;write_kb;write_bandwidth;write_iops;write_runtime_ms;write_slat_min;write_slat_max;write_slat_mean;write_slat_dev;write_clat_min;write_clat_max;write_clat_mean;write_clat_dev;write_clat_pct01;write_clat_pct02;write_clat_pct03;write_clat_pct04;write_clat_pct05;write_clat_pct06;write_clat_pct07;write_clat_pct08;write_clat_pct09;write_clat_pct10;write_clat_pct11;write_clat_pct12;write_clat_pct13;write_clat_pct14;write_clat_pct15;write_clat_pct16;write_clat_pct17;write_clat_pct18;write_clat_pct19;write_clat_pct20;write_tlat_min;write_lat_max;write_lat_mean;write_lat_dev;write_bw_min;write_bw_max;write_bw_agg_pct;write_bw_mean;write_bw_dev;cpu_user;cpu_sys;cpu_csw;cpu_mjf;cpu_minf;iodepth_1;iodepth_2;iodepth_4;iodepth_8;iodepth_16;iodepth_32;iodepth_64;lat_2us;lat_4us;lat_10us;lat_20us;lat_50us;lat_100us;lat_250us;lat_500us;lat_750us;lat_1000us;lat_2ms;lat_4ms;lat_10ms;lat_20ms;lat_50ms;lat_100ms;lat_250ms;lat_500ms;lat_750ms;lat_1000ms;lat_2000ms;lat_over_2000ms;disk_name;disk_read_iops;disk_write_iops;disk_read_merges;disk_write_merges;disk_read_ticks;write_ticks;disk_queue_time;disk_util
+
+
+Trace file format
+-----------------
+
+There are two trace file format that you can encounter. The older (v1) format is
+unsupported since version 1.20-rc3 (March 2008). It will still be described
+below in case that you get an old trace and want to understand it.
+
+In any case the trace is a simple text file with a single action per line.
+
+
+Trace file format v1
+~~~~~~~~~~~~~~~~~~~~
+
+Each line represents a single I/O action in the following format::
+
+ rw, offset, length
+
+where `rw=0/1` for read/write, and the offset and length entries being in bytes.
+
+This format is not supported in fio versions >= 1.20-rc3.
+
+
+Trace file format v2
+~~~~~~~~~~~~~~~~~~~~
+
+The second version of the trace file format was added in fio version 1.17. It
+allows to access more then one file per trace and has a bigger set of possible
+file actions.
+
+The first line of the trace file has to be::
+
+ fio version 2 iolog
+
+Following this can be lines in two different formats, which are described below.
+
+The file management format::
+
+ filename action
+
+The filename is given as an absolute path. The action can be one of these:
+
+**add**
+ Add the given filename to the trace.
+**open**
+ Open the file with the given filename. The filename has to have
+ been added with the **add** action before.
+**close**
+ Close the file with the given filename. The file has to have been
+ opened before.
+
+
+The file I/O action format::
+
+ filename action offset length
+
+The `filename` is given as an absolute path, and has to have been added and
+opened before it can be used with this format. The `offset` and `length` are
+given in bytes. The `action` can be one of these:
+
+**wait**
+ Wait for `offset` microseconds. Everything below 100 is discarded.
+ The time is relative to the previous `wait` statement.
+**read**
+ Read `length` bytes beginning from `offset`.
+**write**
+ Write `length` bytes beginning from `offset`.
+**sync**
+ :manpage:`fsync(2)` the file.
+**datasync**
+ :manpage:`fdatasync(2)` the file.
+**trim**
+ Trim the given file from the given `offset` for `length` bytes.
+
+CPU idleness profiling
+----------------------
+
+In some cases, we want to understand CPU overhead in a test. For example, we
+test patches for the specific goodness of whether they reduce CPU usage.
+Fio implements a balloon approach to create a thread per CPU that runs at idle
+priority, meaning that it only runs when nobody else needs the cpu.
+By measuring the amount of work completed by the thread, idleness of each CPU
+can be derived accordingly.
+
+An unit work is defined as touching a full page of unsigned characters. Mean and
+standard deviation of time to complete an unit work is reported in "unit work"
+section. Options can be chosen to report detailed percpu idleness or overall
+system idleness by aggregating percpu stats.
+
+
+Verification and triggers
+-------------------------
+
+Fio is usually run in one of two ways, when data verification is done. The first
+is a normal write job of some sort with verify enabled. When the write phase has
+completed, fio switches to reads and verifies everything it wrote. The second
+model is running just the write phase, and then later on running the same job
+(but with reads instead of writes) to repeat the same I/O patterns and verify
+the contents. Both of these methods depend on the write phase being completed,
+as fio otherwise has no idea how much data was written.
+
+With verification triggers, fio supports dumping the current write state to
+local files. Then a subsequent read verify workload can load this state and know
+exactly where to stop. This is useful for testing cases where power is cut to a
+server in a managed fashion, for instance.
+
+A verification trigger consists of two things:
+
+1) Storing the write state of each job.
+2) Executing a trigger command.
+
+The write state is relatively small, on the order of hundreds of bytes to single
+kilobytes. It contains information on the number of completions done, the last X
+completions, etc.
+
+A trigger is invoked either through creation ('touch') of a specified file in
+the system, or through a timeout setting. If fio is run with
+:option:`--trigger-file`\= :file:`/tmp/trigger-file`, then it will continually
+check for the existence of :file:`/tmp/trigger-file`. When it sees this file, it
+will fire off the trigger (thus saving state, and executing the trigger
+command).
+
+For client/server runs, there's both a local and remote trigger. If fio is
+running as a server backend, it will send the job states back to the client for
+safe storage, then execute the remote trigger, if specified. If a local trigger
+is specified, the server will still send back the write state, but the client
+will then execute the trigger.
+
+Verification trigger example
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Let's say we want to run a powercut test on the remote machine 'server'. Our
+write workload is in :file:`write-test.fio`. We want to cut power to 'server' at
+some point during the run, and we'll run this test from the safety or our local
+machine, 'localbox'. On the server, we'll start the fio backend normally::
+
+ server# fio --server
+
+and on the client, we'll fire off the workload::
+
+ localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger-remote="bash -c \"echo b > /proc/sysrq-triger\""
+
+We set :file:`/tmp/my-trigger` as the trigger file, and we tell fio to execute::
+
+ echo b > /proc/sysrq-trigger
+
+on the server once it has received the trigger and sent us the write state. This
+will work, but it's not **really** cutting power to the server, it's merely
+abruptly rebooting it. If we have a remote way of cutting power to the server
+through IPMI or similar, we could do that through a local trigger command
+instead. Let's assume we have a script that does IPMI reboot of a given hostname,
+ipmi-reboot. On localbox, we could then have run fio with a local trigger
+instead::
+
+ localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger="ipmi-reboot server"
+
+For this case, fio would wait for the server to send us the write state, then
+execute ``ipmi-reboot server`` when that happened.
+
+Loading verify state
+~~~~~~~~~~~~~~~~~~~~
+
+To load stored write state, a read verification job file must contain the
+:option:`verify_state_load` option. If that is set, fio will load the previously
+stored state. For a local fio run this is done by loading the files directly,
+and on a client/server run, the server backend will ask the client to send the
+files over and load them from there.
+
+
+Log File Formats
+----------------
+
+Fio supports a variety of log file formats, for logging latencies, bandwidth,
+and IOPS. The logs share a common format, which looks like this:
+
+ *time* (`msec`), *value*, *data direction*, *offset*
+
+Time for the log entry is always in milliseconds. The *value* logged depends
+on the type of log, it will be one of the following:
+
+ **Latency log**
+ Value is latency in usecs
+ **Bandwidth log**
+ Value is in KiB/sec
+ **IOPS log**
+ Value is IOPS
+
+*Data direction* is one of the following:
+
+ **0**
+ I/O is a READ
+ **1**
+ I/O is a WRITE
+ **2**
+ I/O is a TRIM
+
+The *offset* is the offset, in bytes, from the start of the file, for that
+particular I/O. The logging of the offset can be toggled with
+:option:`log_offset`.
+
+Fio defaults to logging every individual I/O. When IOPS are logged for individual
+I/Os the value entry will always be 1. If windowed logging is enabled through
+:option:`log_avg_msec`, fio logs the average values over the specified period of time.
+If windowed logging is enabled and :option:`log_max_value` is set, then fio logs
+maximum values in that window instead of averages. Since 'data direction' and
+'offset' are per-I/O values, they aren't applicable if windowed logging is enabled.
+
+Client/server
+-------------
+
+Normally fio is invoked as a stand-alone application on the machine where the
+I/O workload should be generated. However, the backend and frontend of fio can
+be run separately i.e., the fio server can generate an I/O workload on the "Device
+Under Test" while being controlled by a client on another machine.
+
+Start the server on the machine which has access to the storage DUT::
+
+ fio --server=args
+
+where `args` defines what fio listens to. The arguments are of the form
+``type,hostname`` or ``IP,port``. *type* is either ``ip`` (or ip4) for TCP/IP
+v4, ``ip6`` for TCP/IP v6, or ``sock`` for a local unix domain socket.
+*hostname* is either a hostname or IP address, and *port* is the port to listen
+to (only valid for TCP/IP, not a local socket). Some examples:
+
+1) ``fio --server``
+
+ Start a fio server, listening on all interfaces on the default port (8765).
+
+2) ``fio --server=ip:hostname,4444``
+
+ Start a fio server, listening on IP belonging to hostname and on port 4444.
+
+3) ``fio --server=ip6:::1,4444``
+
+ Start a fio server, listening on IPv6 localhost ::1 and on port 4444.
+
+4) ``fio --server=,4444``
+
+ Start a fio server, listening on all interfaces on port 4444.
+
+5) ``fio --server=1.2.3.4``
+
+ Start a fio server, listening on IP 1.2.3.4 on the default port.
+
+6) ``fio --server=sock:/tmp/fio.sock``
+
+ Start a fio server, listening on the local socket :file:`/tmp/fio.sock`.
+
+Once a server is running, a "client" can connect to the fio server with::
+
+ fio <local-args> --client=<server> <remote-args> <job file(s)>
+
+where `local-args` are arguments for the client where it is running, `server`
+is the connect string, and `remote-args` and `job file(s)` are sent to the
+server. The `server` string follows the same format as it does on the server
+side, to allow IP/hostname/socket and port strings.
+
+Fio can connect to multiple servers this way::
+
+ fio --client=<server1> <job file(s)> --client=<server2> <job file(s)>
+
+If the job file is located on the fio server, then you can tell the server to
+load a local file as well. This is done by using :option:`--remote-config` ::
+
+ fio --client=server --remote-config /path/to/file.fio
+
+Then fio will open this local (to the server) job file instead of being passed
+one from the client.
+
+If you have many servers (example: 100 VMs/containers), you can input a pathname
+of a file containing host IPs/names as the parameter value for the
+:option:`--client` option. For example, here is an example :file:`host.list`
+file containing 2 hostnames::
+
+ host1.your.dns.domain
+ host2.your.dns.domain
- Latency log Value is latency in usecs
- Bandwidth log Value is in KiB/sec
- IOPS log Value is IOPS
+The fio command would then be::
-Data direction is one of the following:
+ fio --client=host.list <job file(s)>
- 0 IO is a READ
- 1 IO is a WRITE
- 2 IO is a TRIM
+In this mode, you cannot input server-specific parameters or job files -- all
+servers receive the same job file.
-The offset is the offset, in bytes, from the start of the file, for that
-particular IO. The logging of the offset can be toggled with 'log_offset'.
+In order to let ``fio --client`` runs use a shared filesystem from multiple
+hosts, ``fio --client`` now prepends the IP address of the server to the
+filename. For example, if fio is using the directory :file:`/mnt/nfs/fio` and is
+writing filename :file:`fileio.tmp`, with a :option:`--client` `hostfile`
+containing two hostnames ``h1`` and ``h2`` with IP addresses 192.168.10.120 and
+192.168.10.121, then fio will create two files::
-If windowed logging is enabled through 'log_avg_msec', then fio doesn't log
-individual IOs. Instead of logs the average values over the specified
-period of time. Since 'data direction' and 'offset' are per-IO values,
-they aren't applicable if windowed logging is enabled. If windowed logging
-is enabled and 'log_max_value' is set, then fio logs maximum values in
-that window instead of averages.
+ /mnt/nfs/fio/192.168.10.120.fileio.tmp
+ /mnt/nfs/fio/192.168.10.121.fileio.tmp
projects / fio.git / blobdiff