4 The first step in getting fio to simulate a desired I/O workload, is writing a
5 job file describing that specific setup. A job file may contain any number of
6 threads and/or files -- the typical contents of the job file is a *global*
7 section defining shared parameters, and one or more job sections describing the
8 jobs involved. When run, fio parses this file and sets everything up as
9 described. If we break down a job from top to bottom, it contains the following
14 Defines the I/O pattern issued to the file(s). We may only be reading
15 sequentially from this file(s), or we may be writing randomly. Or even
16 mixing reads and writes, sequentially or randomly.
17 Should we be doing buffered I/O, or direct/raw I/O?
21 In how large chunks are we issuing I/O? This may be a single value,
22 or it may describe a range of block sizes.
26 How much data are we going to be reading/writing.
30 How do we issue I/O? We could be memory mapping the file, we could be
31 using regular read/write, we could be using splice, async I/O, or even
36 If the I/O engine is async, how large a queuing depth do we want to
42 How many files are we spreading the workload over.
44 `Threads, processes and job synchronization`_
46 How many threads or processes should we spread this workload over.
48 The above are the basic parameters defined for a workload, in addition there's a
49 multitude of parameters that modify other aspects of how this job behaves.
55 .. option:: --debug=type
57 Enable verbose tracing `type` of various fio actions. May be ``all`` for all types
58 or individual types separated by a comma (e.g. ``--debug=file,mem`` will
59 enable file and memory debugging). Currently, additional logging is
63 Dump info related to processes.
65 Dump info related to file actions.
67 Dump info related to I/O queuing.
69 Dump info related to memory allocations.
71 Dump info related to blktrace setup.
73 Dump info related to I/O verification.
75 Enable all debug options.
77 Dump info related to random offset generation.
79 Dump info related to option matching and parsing.
81 Dump info related to disk utilization updates.
83 Dump info only related to job number x.
85 Dump info only related to mutex up/down ops.
87 Dump info related to profile extensions.
89 Dump info related to internal time keeping.
91 Dump info related to networking connections.
93 Dump info related to I/O rate switching.
95 Dump info related to log compress/decompress.
97 Show available debug options.
99 .. option:: --parse-only
101 Parse options only, don't start any I/O.
103 .. option:: --output=filename
105 Write output to file `filename`.
107 .. option:: --output-format=format
109 Set the reporting `format` to `normal`, `terse`, `json`, or `json+`. Multiple
110 formats can be selected, separated by a comma. `terse` is a CSV based
111 format. `json+` is like `json`, except it adds a full dump of the latency
114 .. option:: --bandwidth-log
116 Generate aggregate bandwidth logs.
118 .. option:: --minimal
120 Print statistics in a terse, semicolon-delimited format.
122 .. option:: --append-terse
124 Print statistics in selected mode AND terse, semicolon-delimited format.
125 **Deprecated**, use :option:`--output-format` instead to select multiple
128 .. option:: --terse-version=version
130 Set terse `version` output format (default 3, or 2 or 4 or 5).
132 .. option:: --version
134 Print version information and exit.
138 Print a summary of the command line options and exit.
140 .. option:: --cpuclock-test
142 Perform test and validation of internal CPU clock.
144 .. option:: --crctest=[test]
146 Test the speed of the built-in checksumming functions. If no argument is
147 given, all of them are tested. Alternatively, a comma separated list can
148 be passed, in which case the given ones are tested.
150 .. option:: --cmdhelp=command
152 Print help information for `command`. May be ``all`` for all commands.
154 .. option:: --enghelp=[ioengine[,command]]
156 List all commands defined by `ioengine`, or print help for `command`
157 defined by `ioengine`. If no `ioengine` is given, list all
160 .. option:: --showcmd=jobfile
162 Convert `jobfile` to a set of command-line options.
164 .. option:: --readonly
166 Turn on safety read-only checks, preventing writes. The ``--readonly``
167 option is an extra safety guard to prevent users from accidentally starting
168 a write workload when that is not desired. Fio will only write if
169 `rw=write/randwrite/rw/randrw` is given. This extra safety net can be used
170 as an extra precaution as ``--readonly`` will also enable a write check in
171 the I/O engine core to prevent writes due to unknown user space bug(s).
173 .. option:: --eta=when
175 Specifies when real-time ETA estimate should be printed. `when` may be
176 `always`, `never` or `auto`.
178 .. option:: --eta-newline=time
180 Force a new line for every `time` period passed. When the unit is omitted,
181 the value is interpreted in seconds.
183 .. option:: --status-interval=time
185 Force a full status dump of cumulative (from job start) values at `time`
186 intervals. This option does *not* provide per-period measurements. So
187 values such as bandwidth are running averages. When the time unit is omitted,
188 `time` is interpreted in seconds.
190 .. option:: --section=name
192 Only run specified section `name` in job file. Multiple sections can be specified.
193 The ``--section`` option allows one to combine related jobs into one file.
194 E.g. one job file could define light, moderate, and heavy sections. Tell
195 fio to run only the "heavy" section by giving ``--section=heavy``
196 command line option. One can also specify the "write" operations in one
197 section and "verify" operation in another section. The ``--section`` option
198 only applies to job sections. The reserved *global* section is always
201 .. option:: --alloc-size=kb
203 Set the internal smalloc pool size to `kb` in KiB. The
204 ``--alloc-size`` switch allows one to use a larger pool size for smalloc.
205 If running large jobs with randommap enabled, fio can run out of memory.
206 Smalloc is an internal allocator for shared structures from a fixed size
207 memory pool and can grow to 16 pools. The pool size defaults to 16MiB.
209 NOTE: While running :file:`.fio_smalloc.*` backing store files are visible
212 .. option:: --warnings-fatal
214 All fio parser warnings are fatal, causing fio to exit with an
217 .. option:: --max-jobs=nr
219 Set the maximum number of threads/processes to support to `nr`.
221 .. option:: --server=args
223 Start a backend server, with `args` specifying what to listen to.
224 See `Client/Server`_ section.
226 .. option:: --daemonize=pidfile
228 Background a fio server, writing the pid to the given `pidfile` file.
230 .. option:: --client=hostname
232 Instead of running the jobs locally, send and run them on the given `hostname`
233 or set of `hostname`s. See `Client/Server`_ section.
235 .. option:: --remote-config=file
237 Tell fio server to load this local `file`.
239 .. option:: --idle-prof=option
241 Report CPU idleness. `option` is one of the following:
244 Run unit work calibration only and exit.
247 Show aggregate system idleness and unit work.
250 As **system** but also show per CPU idleness.
252 .. option:: --inflate-log=log
254 Inflate and output compressed `log`.
256 .. option:: --trigger-file=file
258 Execute trigger command when `file` exists.
260 .. option:: --trigger-timeout=time
262 Execute trigger at this `time`.
264 .. option:: --trigger=command
266 Set this `command` as local trigger.
268 .. option:: --trigger-remote=command
270 Set this `command` as remote trigger.
272 .. option:: --aux-path=path
274 Use this `path` for fio state generated files.
276 Any parameters following the options will be assumed to be job files, unless
277 they match a job file parameter. Multiple job files can be listed and each job
278 file will be regarded as a separate group. Fio will :option:`stonewall`
279 execution between each group.
285 As previously described, fio accepts one or more job files describing what it is
286 supposed to do. The job file format is the classic ini file, where the names
287 enclosed in [] brackets define the job name. You are free to use any ASCII name
288 you want, except *global* which has special meaning. Following the job name is
289 a sequence of zero or more parameters, one per line, that define the behavior of
290 the job. If the first character in a line is a ';' or a '#', the entire line is
291 discarded as a comment.
293 A *global* section sets defaults for the jobs described in that file. A job may
294 override a *global* section parameter, and a job file may even have several
295 *global* sections if so desired. A job is only affected by a *global* section
298 The :option:`--cmdhelp` option also lists all options. If used with a `command`
299 argument, :option:`--cmdhelp` will detail the given `command`.
301 See the `examples/` directory for inspiration on how to write job files. Note
302 the copyright and license requirements currently apply to `examples/` files.
304 So let's look at a really simple job file that defines two processes, each
305 randomly reading from a 128MiB file:
309 ; -- start job file --
320 As you can see, the job file sections themselves are empty as all the described
321 parameters are shared. As no :option:`filename` option is given, fio makes up a
322 `filename` for each of the jobs as it sees fit. On the command line, this job
323 would look as follows::
325 $ fio --name=global --rw=randread --size=128m --name=job1 --name=job2
328 Let's look at an example that has a number of processes writing randomly to
333 ; -- start job file --
344 Here we have no *global* section, as we only have one job defined anyway. We
345 want to use async I/O here, with a depth of 4 for each file. We also increased
346 the buffer size used to 32KiB and define numjobs to 4 to fork 4 identical
347 jobs. The result is 4 processes each randomly writing to their own 64MiB
348 file. Instead of using the above job file, you could have given the parameters
349 on the command line. For this case, you would specify::
351 $ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4
353 When fio is utilized as a basis of any reasonably large test suite, it might be
354 desirable to share a set of standardized settings across multiple job files.
355 Instead of copy/pasting such settings, any section may pull in an external
356 :file:`filename.fio` file with *include filename* directive, as in the following
359 ; -- start job file including.fio --
363 include glob-include.fio
370 include test-include.fio
371 ; -- end job file including.fio --
375 ; -- start job file glob-include.fio --
378 ; -- end job file glob-include.fio --
382 ; -- start job file test-include.fio --
385 ; -- end job file test-include.fio --
387 Settings pulled into a section apply to that section only (except *global*
388 section). Include directives may be nested in that any included file may contain
389 further include directive(s). Include files may not contain [] sections.
392 Environment variables
393 ~~~~~~~~~~~~~~~~~~~~~
395 Fio also supports environment variable expansion in job files. Any sub-string of
396 the form ``${VARNAME}`` as part of an option value (in other words, on the right
397 of the '='), will be expanded to the value of the environment variable called
398 `VARNAME`. If no such environment variable is defined, or `VARNAME` is the
399 empty string, the empty string will be substituted.
401 As an example, let's look at a sample fio invocation and job file::
403 $ SIZE=64m NUMJOBS=4 fio jobfile.fio
407 ; -- start job file --
414 This will expand to the following equivalent job file at runtime:
418 ; -- start job file --
425 Fio ships with a few example job files, you can also look there for inspiration.
430 Additionally, fio has a set of reserved keywords that will be replaced
431 internally with the appropriate value. Those keywords are:
435 The architecture page size of the running system.
439 Megabytes of total memory in the system.
443 Number of online available CPUs.
445 These can be used on the command line or in the job file, and will be
446 automatically substituted with the current system values when the job is
447 run. Simple math is also supported on these keywords, so you can perform actions
452 and get that properly expanded to 8 times the size of memory in the machine.
458 This section describes in details each parameter associated with a job. Some
459 parameters take an option of a given type, such as an integer or a
460 string. Anywhere a numeric value is required, an arithmetic expression may be
461 used, provided it is surrounded by parentheses. Supported operators are:
470 For time values in expressions, units are microseconds by default. This is
471 different than for time values not in expressions (not enclosed in
472 parentheses). The following types are used:
479 String: A sequence of alphanumeric characters.
482 Integer with possible time suffix. Without a unit value is interpreted as
483 seconds unless otherwise specified. Accepts a suffix of 'd' for days, 'h' for
484 hours, 'm' for minutes, 's' for seconds, 'ms' (or 'msec') for milliseconds and
485 'us' (or 'usec') for microseconds. For example, use 10m for 10 minutes.
490 Integer. A whole number value, which may contain an integer prefix
491 and an integer suffix:
493 [*integer prefix*] **number** [*integer suffix*]
495 The optional *integer prefix* specifies the number's base. The default
496 is decimal. *0x* specifies hexadecimal.
498 The optional *integer suffix* specifies the number's units, and includes an
499 optional unit prefix and an optional unit. For quantities of data, the
500 default unit is bytes. For quantities of time, the default unit is seconds
501 unless otherwise specified.
503 With :option:`kb_base`\=1000, fio follows international standards for unit
504 prefixes. To specify power-of-10 decimal values defined in the
505 International System of Units (SI):
507 * *K* -- means kilo (K) or 1000
508 * *M* -- means mega (M) or 1000**2
509 * *G* -- means giga (G) or 1000**3
510 * *T* -- means tera (T) or 1000**4
511 * *P* -- means peta (P) or 1000**5
513 To specify power-of-2 binary values defined in IEC 80000-13:
515 * *Ki* -- means kibi (Ki) or 1024
516 * *Mi* -- means mebi (Mi) or 1024**2
517 * *Gi* -- means gibi (Gi) or 1024**3
518 * *Ti* -- means tebi (Ti) or 1024**4
519 * *Pi* -- means pebi (Pi) or 1024**5
521 With :option:`kb_base`\=1024 (the default), the unit prefixes are opposite
522 from those specified in the SI and IEC 80000-13 standards to provide
523 compatibility with old scripts. For example, 4k means 4096.
525 For quantities of data, an optional unit of 'B' may be included
526 (e.g., 'kB' is the same as 'k').
528 The *integer suffix* is not case sensitive (e.g., m/mi mean mebi/mega,
529 not milli). 'b' and 'B' both mean byte, not bit.
531 Examples with :option:`kb_base`\=1000:
533 * *4 KiB*: 4096, 4096b, 4096B, 4ki, 4kib, 4kiB, 4Ki, 4KiB
534 * *1 MiB*: 1048576, 1mi, 1024ki
535 * *1 MB*: 1000000, 1m, 1000k
536 * *1 TiB*: 1099511627776, 1ti, 1024gi, 1048576mi
537 * *1 TB*: 1000000000, 1t, 1000m, 1000000k
539 Examples with :option:`kb_base`\=1024 (default):
541 * *4 KiB*: 4096, 4096b, 4096B, 4k, 4kb, 4kB, 4K, 4KB
542 * *1 MiB*: 1048576, 1m, 1024k
543 * *1 MB*: 1000000, 1mi, 1000ki
544 * *1 TiB*: 1099511627776, 1t, 1024g, 1048576m
545 * *1 TB*: 1000000000, 1ti, 1000mi, 1000000ki
547 To specify times (units are not case sensitive):
551 * *M* -- means minutes
552 * *s* -- or sec means seconds (default)
553 * *ms* -- or *msec* means milliseconds
554 * *us* -- or *usec* means microseconds
556 If the option accepts an upper and lower range, use a colon ':' or
557 minus '-' to separate such values. See :ref:`irange <irange>`.
558 If the lower value specified happens to be larger than the upper value
559 the two values are swapped.
564 Boolean. Usually parsed as an integer, however only defined for
565 true and false (1 and 0).
570 Integer range with suffix. Allows value range to be given, such as
571 1024-4096. A colon may also be used as the separator, e.g. 1k:4k. If the
572 option allows two sets of ranges, they can be specified with a ',' or '/'
573 delimiter: 1k-4k/8k-32k. Also see :ref:`int <int>`.
576 A list of floating point numbers, separated by a ':' character.
578 With the above in mind, here follows the complete list of fio job parameters.
584 .. option:: kb_base=int
586 Select the interpretation of unit prefixes in input parameters.
589 Inputs comply with IEC 80000-13 and the International
590 System of Units (SI). Use:
592 - power-of-2 values with IEC prefixes (e.g., KiB)
593 - power-of-10 values with SI prefixes (e.g., kB)
596 Compatibility mode (default). To avoid breaking old scripts:
598 - power-of-2 values with SI prefixes
599 - power-of-10 values with IEC prefixes
601 See :option:`bs` for more details on input parameters.
603 Outputs always use correct prefixes. Most outputs include both
606 bw=2383.3kB/s (2327.4KiB/s)
608 If only one value is reported, then kb_base selects the one to use:
610 **1000** -- SI prefixes
612 **1024** -- IEC prefixes
614 .. option:: unit_base=int
616 Base unit for reporting. Allowed values are:
619 Use auto-detection (default).
631 ASCII name of the job. This may be used to override the name printed by fio
632 for this job. Otherwise the job name is used. On the command line this
633 parameter has the special purpose of also signaling the start of a new job.
635 .. option:: description=str
637 Text description of the job. Doesn't do anything except dump this text
638 description when this job is run. It's not parsed.
640 .. option:: loops=int
642 Run the specified number of iterations of this job. Used to repeat the same
643 workload a given number of times. Defaults to 1.
645 .. option:: numjobs=int
647 Create the specified number of clones of this job. Each clone of job
648 is spawned as an independent thread or process. May be used to setup a
649 larger number of threads/processes doing the same thing. Each thread is
650 reported separately; to see statistics for all clones as a whole, use
651 :option:`group_reporting` in conjunction with :option:`new_group`.
652 See :option:`--max-jobs`. Default: 1.
655 Time related parameters
656 ~~~~~~~~~~~~~~~~~~~~~~~
658 .. option:: runtime=time
660 Tell fio to terminate processing after the specified period of time. It
661 can be quite hard to determine for how long a specified job will run, so
662 this parameter is handy to cap the total runtime to a given time. When
663 the unit is omitted, the value is intepreted in seconds.
665 .. option:: time_based
667 If set, fio will run for the duration of the :option:`runtime` specified
668 even if the file(s) are completely read or written. It will simply loop over
669 the same workload as many times as the :option:`runtime` allows.
671 .. option:: startdelay=irange(time)
673 Delay the start of job for the specified amount of time. Can be a single
674 value or a range. When given as a range, each thread will choose a value
675 randomly from within the range. Value is in seconds if a unit is omitted.
677 .. option:: ramp_time=time
679 If set, fio will run the specified workload for this amount of time before
680 logging any performance numbers. Useful for letting performance settle
681 before logging results, thus minimizing the runtime required for stable
682 results. Note that the ``ramp_time`` is considered lead in time for a job,
683 thus it will increase the total runtime if a special timeout or
684 :option:`runtime` is specified. When the unit is omitted, the value is
687 .. option:: clocksource=str
689 Use the given clocksource as the base of timing. The supported options are:
692 :manpage:`gettimeofday(2)`
695 :manpage:`clock_gettime(2)`
698 Internal CPU clock source
700 cpu is the preferred clocksource if it is reliable, as it is very fast (and
701 fio is heavy on time calls). Fio will automatically use this clocksource if
702 it's supported and considered reliable on the system it is running on,
703 unless another clocksource is specifically set. For x86/x86-64 CPUs, this
704 means supporting TSC Invariant.
706 .. option:: gtod_reduce=bool
708 Enable all of the :manpage:`gettimeofday(2)` reducing options
709 (:option:`disable_clat`, :option:`disable_slat`, :option:`disable_bw_measurement`) plus
710 reduce precision of the timeout somewhat to really shrink the
711 :manpage:`gettimeofday(2)` call count. With this option enabled, we only do
712 about 0.4% of the :manpage:`gettimeofday(2)` calls we would have done if all
713 time keeping was enabled.
715 .. option:: gtod_cpu=int
717 Sometimes it's cheaper to dedicate a single thread of execution to just
718 getting the current time. Fio (and databases, for instance) are very
719 intensive on :manpage:`gettimeofday(2)` calls. With this option, you can set
720 one CPU aside for doing nothing but logging current time to a shared memory
721 location. Then the other threads/processes that run I/O workloads need only
722 copy that segment, instead of entering the kernel with a
723 :manpage:`gettimeofday(2)` call. The CPU set aside for doing these time
724 calls will be excluded from other uses. Fio will manually clear it from the
725 CPU mask of other jobs.
731 .. option:: directory=str
733 Prefix filenames with this directory. Used to place files in a different
734 location than :file:`./`. You can specify a number of directories by
735 separating the names with a ':' character. These directories will be
736 assigned equally distributed to job clones created by :option:`numjobs` as
737 long as they are using generated filenames. If specific `filename(s)` are
738 set fio will use the first listed directory, and thereby matching the
739 `filename` semantic which generates a file each clone if not specified, but
740 let all clones use the same if set.
742 See the :option:`filename` option for information on how to escape "``:``" and
743 "``\``" characters within the directory path itself.
745 .. option:: filename=str
747 Fio normally makes up a `filename` based on the job name, thread number, and
748 file number (see :option:`filename_format`). If you want to share files
749 between threads in a job or several
750 jobs with fixed file paths, specify a `filename` for each of them to override
751 the default. If the ioengine is file based, you can specify a number of files
752 by separating the names with a ':' colon. So if you wanted a job to open
753 :file:`/dev/sda` and :file:`/dev/sdb` as the two working files, you would use
754 ``filename=/dev/sda:/dev/sdb``. This also means that whenever this option is
755 specified, :option:`nrfiles` is ignored. The size of regular files specified
756 by this option will be :option:`size` divided by number of files unless an
757 explicit size is specified by :option:`filesize`.
759 Each colon and backslash in the wanted path must be escaped with a ``\``
760 character. For instance, if the path is :file:`/dev/dsk/foo@3,0:c` then you
761 would use ``filename=/dev/dsk/foo@3,0\:c`` and if the path is
762 :file:`F:\\filename` then you would use ``filename=F\:\\filename``.
764 On Windows, disk devices are accessed as :file:`\\\\.\\PhysicalDrive0` for
765 the first device, :file:`\\\\.\\PhysicalDrive1` for the second etc.
766 Note: Windows and FreeBSD prevent write access to areas
767 of the disk containing in-use data (e.g. filesystems).
769 The filename "`-`" is a reserved name, meaning *stdin* or *stdout*. Which
770 of the two depends on the read/write direction set.
772 .. option:: filename_format=str
774 If sharing multiple files between jobs, it is usually necessary to have fio
775 generate the exact names that you want. By default, fio will name a file
776 based on the default file format specification of
777 :file:`jobname.jobnumber.filenumber`. With this option, that can be
778 customized. Fio will recognize and replace the following keywords in this
782 The name of the worker thread or process.
784 The incremental number of the worker thread or process.
786 The incremental number of the file for that worker thread or
789 To have dependent jobs share a set of files, this option can be set to have
790 fio generate filenames that are shared between the two. For instance, if
791 :file:`testfiles.$filenum` is specified, file number 4 for any job will be
792 named :file:`testfiles.4`. The default of :file:`$jobname.$jobnum.$filenum`
793 will be used if no other format specifier is given.
795 .. option:: unique_filename=bool
797 To avoid collisions between networked clients, fio defaults to prefixing any
798 generated filenames (with a directory specified) with the source of the
799 client connecting. To disable this behavior, set this option to 0.
801 .. option:: opendir=str
803 Recursively open any files below directory `str`.
805 .. option:: lockfile=str
807 Fio defaults to not locking any files before it does I/O to them. If a file
808 or file descriptor is shared, fio can serialize I/O to that file to make the
809 end result consistent. This is usual for emulating real workloads that share
810 files. The lock modes are:
813 No locking. The default.
815 Only one thread or process may do I/O at a time, excluding all
818 Read-write locking on the file. Many readers may
819 access the file at the same time, but writes get exclusive access.
821 .. option:: nrfiles=int
823 Number of files to use for this job. Defaults to 1. The size of files
824 will be :option:`size` divided by this unless explicit size is specified by
825 :option:`filesize`. Files are created for each thread separately, and each
826 file will have a file number within its name by default, as explained in
827 :option:`filename` section.
830 .. option:: openfiles=int
832 Number of files to keep open at the same time. Defaults to the same as
833 :option:`nrfiles`, can be set smaller to limit the number simultaneous
836 .. option:: file_service_type=str
838 Defines how fio decides which file from a job to service next. The following
842 Choose a file at random.
845 Round robin over opened files. This is the default.
848 Finish one file before moving on to the next. Multiple files can
849 still be open depending on :option:`openfiles`.
852 Use a *Zipf* distribution to decide what file to access.
855 Use a *Pareto* distribution to decide what file to access.
858 Use a *Gaussian* (normal) distribution to decide what file to
864 For *random*, *roundrobin*, and *sequential*, a postfix can be appended to
865 tell fio how many I/Os to issue before switching to a new file. For example,
866 specifying ``file_service_type=random:8`` would cause fio to issue
867 8 I/Os before selecting a new file at random. For the non-uniform
868 distributions, a floating point postfix can be given to influence how the
869 distribution is skewed. See :option:`random_distribution` for a description
870 of how that would work.
872 .. option:: ioscheduler=str
874 Attempt to switch the device hosting the file to the specified I/O scheduler
877 .. option:: create_serialize=bool
879 If true, serialize the file creation for the jobs. This may be handy to
880 avoid interleaving of data files, which may greatly depend on the filesystem
881 used and even the number of processors in the system. Default: true.
883 .. option:: create_fsync=bool
885 :manpage:`fsync(2)` the data file after creation. This is the default.
887 .. option:: create_on_open=bool
889 If true, don't pre-create files but allow the job's open() to create a file
890 when it's time to do I/O. Default: false -- pre-create all necessary files
893 .. option:: create_only=bool
895 If true, fio will only run the setup phase of the job. If files need to be
896 laid out or updated on disk, only that will be done -- the actual job contents
897 are not executed. Default: false.
899 .. option:: allow_file_create=bool
901 If true, fio is permitted to create files as part of its workload. If this
902 option is false, then fio will error out if
903 the files it needs to use don't already exist. Default: true.
905 .. option:: allow_mounted_write=bool
907 If this isn't set, fio will abort jobs that are destructive (e.g. that write)
908 to what appears to be a mounted device or partition. This should help catch
909 creating inadvertently destructive tests, not realizing that the test will
910 destroy data on the mounted file system. Note that some platforms don't allow
911 writing against a mounted device regardless of this option. Default: false.
913 .. option:: pre_read=bool
915 If this is given, files will be pre-read into memory before starting the
916 given I/O operation. This will also clear the :option:`invalidate` flag,
917 since it is pointless to pre-read and then drop the cache. This will only
918 work for I/O engines that are seek-able, since they allow you to read the
919 same data multiple times. Thus it will not work on non-seekable I/O engines
920 (e.g. network, splice). Default: false.
922 .. option:: unlink=bool
924 Unlink the job files when done. Not the default, as repeated runs of that
925 job would then waste time recreating the file set again and again. Default:
928 .. option:: unlink_each_loop=bool
930 Unlink job files after each iteration or loop. Default: false.
932 .. option:: zonesize=int
934 Divide a file into zones of the specified size. See :option:`zoneskip`.
936 .. option:: zonerange=int
938 Give size of an I/O zone. See :option:`zoneskip`.
940 .. option:: zoneskip=int
942 Skip the specified number of bytes when :option:`zonesize` data has been
943 read. The two zone options can be used to only do I/O on zones of a file.
949 .. option:: direct=bool
951 If value is true, use non-buffered I/O. This is usually O_DIRECT. Note that
952 OpenBSD and ZFS on Solaris don't support direct I/O. On Windows the synchronous
953 ioengines don't support direct I/O. Default: false.
955 .. option:: atomic=bool
957 If value is true, attempt to use atomic direct I/O. Atomic writes are
958 guaranteed to be stable once acknowledged by the operating system. Only
959 Linux supports O_ATOMIC right now.
961 .. option:: buffered=bool
963 If value is true, use buffered I/O. This is the opposite of the
964 :option:`direct` option. Defaults to true.
966 .. option:: readwrite=str, rw=str
968 Type of I/O pattern. Accepted values are:
975 Sequential trims (Linux block devices only).
981 Random trims (Linux block devices only).
983 Sequential mixed reads and writes.
985 Random mixed reads and writes.
987 Sequential trim+write sequences. Blocks will be trimmed first,
988 then the same blocks will be written to.
990 Fio defaults to read if the option is not specified. For the mixed I/O
991 types, the default is to split them 50/50. For certain types of I/O the
992 result may still be skewed a bit, since the speed may be different.
994 It is possible to specify the number of I/Os to do before getting a new
995 offset by appending ``:<nr>`` to the end of the string given. For a
996 random read, it would look like ``rw=randread:8`` for passing in an offset
997 modifier with a value of 8. If the suffix is used with a sequential I/O
998 pattern, then the *<nr>* value specified will be **added** to the generated
999 offset for each I/O turning sequential I/O into sequential I/O with holes.
1000 For instance, using ``rw=write:4k`` will skip 4k for every write. Also see
1001 the :option:`rw_sequencer` option.
1003 .. option:: rw_sequencer=str
1005 If an offset modifier is given by appending a number to the ``rw=<str>``
1006 line, then this option controls how that number modifies the I/O offset
1007 being generated. Accepted values are:
1010 Generate sequential offset.
1012 Generate the same offset.
1014 ``sequential`` is only useful for random I/O, where fio would normally
1015 generate a new random offset for every I/O. If you append e.g. 8 to randread,
1016 you would get a new random offset for every 8 I/Os. The result would be a
1017 seek for only every 8 I/Os, instead of for every I/O. Use ``rw=randread:8``
1018 to specify that. As sequential I/O is already sequential, setting
1019 ``sequential`` for that would not result in any differences. ``identical``
1020 behaves in a similar fashion, except it sends the same offset 8 number of
1021 times before generating a new offset.
1023 .. option:: unified_rw_reporting=bool
1025 Fio normally reports statistics on a per data direction basis, meaning that
1026 reads, writes, and trims are accounted and reported separately. If this
1027 option is set fio sums the results and report them as "mixed" instead.
1029 .. option:: randrepeat=bool
1031 Seed the random number generator used for random I/O patterns in a
1032 predictable way so the pattern is repeatable across runs. Default: true.
1034 .. option:: allrandrepeat=bool
1036 Seed all random number generators in a predictable way so results are
1037 repeatable across runs. Default: false.
1039 .. option:: randseed=int
1041 Seed the random number generators based on this seed value, to be able to
1042 control what sequence of output is being generated. If not set, the random
1043 sequence depends on the :option:`randrepeat` setting.
1045 .. option:: fallocate=str
1047 Whether pre-allocation is performed when laying down files.
1048 Accepted values are:
1051 Do not pre-allocate space.
1054 Use a platform's native pre-allocation call but fall back to
1055 **none** behavior if it fails/is not implemented.
1058 Pre-allocate via :manpage:`posix_fallocate(3)`.
1061 Pre-allocate via :manpage:`fallocate(2)` with
1062 FALLOC_FL_KEEP_SIZE set.
1065 Backward-compatible alias for **none**.
1068 Backward-compatible alias for **posix**.
1070 May not be available on all supported platforms. **keep** is only available
1071 on Linux. If using ZFS on Solaris this cannot be set to **posix**
1072 because ZFS doesn't support pre-allocation. Default: **native** if any
1073 pre-allocation methods are available, **none** if not.
1075 .. option:: fadvise_hint=str
1077 Use :manpage:`posix_fadvise(2)` to advise the kernel on what I/O patterns
1078 are likely to be issued. Accepted values are:
1081 Backwards-compatible hint for "no hint".
1084 Backwards compatible hint for "advise with fio workload type". This
1085 uses **FADV_RANDOM** for a random workload, and **FADV_SEQUENTIAL**
1086 for a sequential workload.
1089 Advise using **FADV_SEQUENTIAL**.
1092 Advise using **FADV_RANDOM**.
1094 .. option:: write_hint=str
1096 Use :manpage:`fcntl(2)` to advise the kernel what life time to expect
1097 from a write. Only supported on Linux, as of version 4.13. Accepted
1101 No particular life time associated with this file.
1104 Data written to this file has a short life time.
1107 Data written to this file has a medium life time.
1110 Data written to this file has a long life time.
1113 Data written to this file has a very long life time.
1115 The values are all relative to each other, and no absolute meaning
1116 should be associated with them.
1118 .. option:: offset=int
1120 Start I/O at the provided offset in the file, given as either a fixed size in
1121 bytes or a percentage. If a percentage is given, the next ``blockalign``-ed
1122 offset will be used. Data before the given offset will not be touched. This
1123 effectively caps the file size at `real_size - offset`. Can be combined with
1124 :option:`size` to constrain the start and end range of the I/O workload.
1125 A percentage can be specified by a number between 1 and 100 followed by '%',
1126 for example, ``offset=20%`` to specify 20%.
1128 .. option:: offset_increment=int
1130 If this is provided, then the real offset becomes `offset + offset_increment
1131 * thread_number`, where the thread number is a counter that starts at 0 and
1132 is incremented for each sub-job (i.e. when :option:`numjobs` option is
1133 specified). This option is useful if there are several jobs which are
1134 intended to operate on a file in parallel disjoint segments, with even
1135 spacing between the starting points.
1137 .. option:: number_ios=int
1139 Fio will normally perform I/Os until it has exhausted the size of the region
1140 set by :option:`size`, or if it exhaust the allocated time (or hits an error
1141 condition). With this setting, the range/size can be set independently of
1142 the number of I/Os to perform. When fio reaches this number, it will exit
1143 normally and report status. Note that this does not extend the amount of I/O
1144 that will be done, it will only stop fio if this condition is met before
1145 other end-of-job criteria.
1147 .. option:: fsync=int
1149 If writing to a file, issue an :manpage:`fsync(2)` (or its equivalent) of
1150 the dirty data for every number of blocks given. For example, if you give 32
1151 as a parameter, fio will sync the file after every 32 writes issued. If fio is
1152 using non-buffered I/O, we may not sync the file. The exception is the sg
1153 I/O engine, which synchronizes the disk cache anyway. Defaults to 0, which
1154 means fio does not periodically issue and wait for a sync to complete. Also
1155 see :option:`end_fsync` and :option:`fsync_on_close`.
1157 .. option:: fdatasync=int
1159 Like :option:`fsync` but uses :manpage:`fdatasync(2)` to only sync data and
1160 not metadata blocks. In Windows, FreeBSD, and DragonFlyBSD there is no
1161 :manpage:`fdatasync(2)` so this falls back to using :manpage:`fsync(2)`.
1162 Defaults to 0, which means fio does not periodically issue and wait for a
1163 data-only sync to complete.
1165 .. option:: write_barrier=int
1167 Make every `N-th` write a barrier write.
1169 .. option:: sync_file_range=str:int
1171 Use :manpage:`sync_file_range(2)` for every `int` number of write
1172 operations. Fio will track range of writes that have happened since the last
1173 :manpage:`sync_file_range(2)` call. `str` can currently be one or more of:
1176 SYNC_FILE_RANGE_WAIT_BEFORE
1178 SYNC_FILE_RANGE_WRITE
1180 SYNC_FILE_RANGE_WAIT_AFTER
1182 So if you do ``sync_file_range=wait_before,write:8``, fio would use
1183 ``SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE`` for every 8
1184 writes. Also see the :manpage:`sync_file_range(2)` man page. This option is
1187 .. option:: overwrite=bool
1189 If true, writes to a file will always overwrite existing data. If the file
1190 doesn't already exist, it will be created before the write phase begins. If
1191 the file exists and is large enough for the specified write phase, nothing
1192 will be done. Default: false.
1194 .. option:: end_fsync=bool
1196 If true, :manpage:`fsync(2)` file contents when a write stage has completed.
1199 .. option:: fsync_on_close=bool
1201 If true, fio will :manpage:`fsync(2)` a dirty file on close. This differs
1202 from :option:`end_fsync` in that it will happen on every file close, not
1203 just at the end of the job. Default: false.
1205 .. option:: rwmixread=int
1207 Percentage of a mixed workload that should be reads. Default: 50.
1209 .. option:: rwmixwrite=int
1211 Percentage of a mixed workload that should be writes. If both
1212 :option:`rwmixread` and :option:`rwmixwrite` is given and the values do not
1213 add up to 100%, the latter of the two will be used to override the
1214 first. This may interfere with a given rate setting, if fio is asked to
1215 limit reads or writes to a certain rate. If that is the case, then the
1216 distribution may be skewed. Default: 50.
1218 .. option:: random_distribution=str:float[,str:float][,str:float]
1220 By default, fio will use a completely uniform random distribution when asked
1221 to perform random I/O. Sometimes it is useful to skew the distribution in
1222 specific ways, ensuring that some parts of the data is more hot than others.
1223 fio includes the following distribution models:
1226 Uniform random distribution
1235 Normal (Gaussian) distribution
1238 Zoned random distribution
1240 When using a **zipf** or **pareto** distribution, an input value is also
1241 needed to define the access pattern. For **zipf**, this is the `Zipf
1242 theta`. For **pareto**, it's the `Pareto power`. Fio includes a test
1243 program, :command:`fio-genzipf`, that can be used visualize what the given input
1244 values will yield in terms of hit rates. If you wanted to use **zipf** with
1245 a `theta` of 1.2, you would use ``random_distribution=zipf:1.2`` as the
1246 option. If a non-uniform model is used, fio will disable use of the random
1247 map. For the **normal** distribution, a normal (Gaussian) deviation is
1248 supplied as a value between 0 and 100.
1250 For a **zoned** distribution, fio supports specifying percentages of I/O
1251 access that should fall within what range of the file or device. For
1252 example, given a criteria of:
1254 * 60% of accesses should be to the first 10%
1255 * 30% of accesses should be to the next 20%
1256 * 8% of accesses should be to the next 30%
1257 * 2% of accesses should be to the next 40%
1259 we can define that through zoning of the random accesses. For the above
1260 example, the user would do::
1262 random_distribution=zoned:60/10:30/20:8/30:2/40
1264 similarly to how :option:`bssplit` works for setting ranges and percentages
1265 of block sizes. Like :option:`bssplit`, it's possible to specify separate
1266 zones for reads, writes, and trims. If just one set is given, it'll apply to
1269 .. option:: percentage_random=int[,int][,int]
1271 For a random workload, set how big a percentage should be random. This
1272 defaults to 100%, in which case the workload is fully random. It can be set
1273 from anywhere from 0 to 100. Setting it to 0 would make the workload fully
1274 sequential. Any setting in between will result in a random mix of sequential
1275 and random I/O, at the given percentages. Comma-separated values may be
1276 specified for reads, writes, and trims as described in :option:`blocksize`.
1278 .. option:: norandommap
1280 Normally fio will cover every block of the file when doing random I/O. If
1281 this option is given, fio will just get a new random offset without looking
1282 at past I/O history. This means that some blocks may not be read or written,
1283 and that some blocks may be read/written more than once. If this option is
1284 used with :option:`verify` and multiple blocksizes (via :option:`bsrange`),
1285 only intact blocks are verified, i.e., partially-overwritten blocks are
1288 .. option:: softrandommap=bool
1290 See :option:`norandommap`. If fio runs with the random block map enabled and
1291 it fails to allocate the map, if this option is set it will continue without
1292 a random block map. As coverage will not be as complete as with random maps,
1293 this option is disabled by default.
1295 .. option:: random_generator=str
1297 Fio supports the following engines for generating I/O offsets for random I/O:
1300 Strong 2^88 cycle random number generator.
1302 Linear feedback shift register generator.
1304 Strong 64-bit 2^258 cycle random number generator.
1306 **tausworthe** is a strong random number generator, but it requires tracking
1307 on the side if we want to ensure that blocks are only read or written
1308 once. **lfsr** guarantees that we never generate the same offset twice, and
1309 it's also less computationally expensive. It's not a true random generator,
1310 however, though for I/O purposes it's typically good enough. **lfsr** only
1311 works with single block sizes, not with workloads that use multiple block
1312 sizes. If used with such a workload, fio may read or write some blocks
1313 multiple times. The default value is **tausworthe**, unless the required
1314 space exceeds 2^32 blocks. If it does, then **tausworthe64** is
1315 selected automatically.
1321 .. option:: blocksize=int[,int][,int], bs=int[,int][,int]
1323 The block size in bytes used for I/O units. Default: 4096. A single value
1324 applies to reads, writes, and trims. Comma-separated values may be
1325 specified for reads, writes, and trims. A value not terminated in a comma
1326 applies to subsequent types.
1331 means 256k for reads, writes and trims.
1334 means 8k for reads, 32k for writes and trims.
1337 means 8k for reads, 32k for writes, and default for trims.
1340 means default for reads, 8k for writes and trims.
1343 means default for reads, 8k for writes, and default for trims.
1345 .. option:: blocksize_range=irange[,irange][,irange], bsrange=irange[,irange][,irange]
1347 A range of block sizes in bytes for I/O units. The issued I/O unit will
1348 always be a multiple of the minimum size, unless
1349 :option:`blocksize_unaligned` is set.
1351 Comma-separated ranges may be specified for reads, writes, and trims as
1352 described in :option:`blocksize`.
1354 Example: ``bsrange=1k-4k,2k-8k``.
1356 .. option:: bssplit=str[,str][,str]
1358 Sometimes you want even finer grained control of the block sizes issued, not
1359 just an even split between them. This option allows you to weight various
1360 block sizes, so that you are able to define a specific amount of block sizes
1361 issued. The format for this option is::
1363 bssplit=blocksize/percentage:blocksize/percentage
1365 for as many block sizes as needed. So if you want to define a workload that
1366 has 50% 64k blocks, 10% 4k blocks, and 40% 32k blocks, you would write::
1368 bssplit=4k/10:64k/50:32k/40
1370 Ordering does not matter. If the percentage is left blank, fio will fill in
1371 the remaining values evenly. So a bssplit option like this one::
1373 bssplit=4k/50:1k/:32k/
1375 would have 50% 4k ios, and 25% 1k and 32k ios. The percentages always add up
1376 to 100, if bssplit is given a range that adds up to more, it will error out.
1378 Comma-separated values may be specified for reads, writes, and trims as
1379 described in :option:`blocksize`.
1381 If you want a workload that has 50% 2k reads and 50% 4k reads, while having
1382 90% 4k writes and 10% 8k writes, you would specify::
1384 bssplit=2k/50:4k/50,4k/90,8k/10
1386 .. option:: blocksize_unaligned, bs_unaligned
1388 If set, fio will issue I/O units with any size within
1389 :option:`blocksize_range`, not just multiples of the minimum size. This
1390 typically won't work with direct I/O, as that normally requires sector
1393 .. option:: bs_is_seq_rand=bool
1395 If this option is set, fio will use the normal read,write blocksize settings
1396 as sequential,random blocksize settings instead. Any random read or write
1397 will use the WRITE blocksize settings, and any sequential read or write will
1398 use the READ blocksize settings.
1400 .. option:: blockalign=int[,int][,int], ba=int[,int][,int]
1402 Boundary to which fio will align random I/O units. Default:
1403 :option:`blocksize`. Minimum alignment is typically 512b for using direct
1404 I/O, though it usually depends on the hardware block size. This option is
1405 mutually exclusive with using a random map for files, so it will turn off
1406 that option. Comma-separated values may be specified for reads, writes, and
1407 trims as described in :option:`blocksize`.
1413 .. option:: zero_buffers
1415 Initialize buffers with all zeros. Default: fill buffers with random data.
1417 .. option:: refill_buffers
1419 If this option is given, fio will refill the I/O buffers on every
1420 submit. The default is to only fill it at init time and reuse that
1421 data. Only makes sense if zero_buffers isn't specified, naturally. If data
1422 verification is enabled, `refill_buffers` is also automatically enabled.
1424 .. option:: scramble_buffers=bool
1426 If :option:`refill_buffers` is too costly and the target is using data
1427 deduplication, then setting this option will slightly modify the I/O buffer
1428 contents to defeat normal de-dupe attempts. This is not enough to defeat
1429 more clever block compression attempts, but it will stop naive dedupe of
1430 blocks. Default: true.
1432 .. option:: buffer_compress_percentage=int
1434 If this is set, then fio will attempt to provide I/O buffer content (on
1435 WRITEs) that compresses to the specified level. Fio does this by providing a
1436 mix of random data and a fixed pattern. The fixed pattern is either zeros,
1437 or the pattern specified by :option:`buffer_pattern`. If the pattern option
1438 is used, it might skew the compression ratio slightly. Note that this is per
1439 block size unit, for file/disk wide compression level that matches this
1440 setting, you'll also want to set :option:`refill_buffers`.
1442 .. option:: buffer_compress_chunk=int
1444 See :option:`buffer_compress_percentage`. This setting allows fio to manage
1445 how big the ranges of random data and zeroed data is. Without this set, fio
1446 will provide :option:`buffer_compress_percentage` of blocksize random data,
1447 followed by the remaining zeroed. With this set to some chunk size smaller
1448 than the block size, fio can alternate random and zeroed data throughout the
1451 .. option:: buffer_pattern=str
1453 If set, fio will fill the I/O buffers with this pattern or with the contents
1454 of a file. If not set, the contents of I/O buffers are defined by the other
1455 options related to buffer contents. The setting can be any pattern of bytes,
1456 and can be prefixed with 0x for hex values. It may also be a string, where
1457 the string must then be wrapped with ``""``. Or it may also be a filename,
1458 where the filename must be wrapped with ``''`` in which case the file is
1459 opened and read. Note that not all the file contents will be read if that
1460 would cause the buffers to overflow. So, for example::
1462 buffer_pattern='filename'
1466 buffer_pattern="abcd"
1474 buffer_pattern=0xdeadface
1476 Also you can combine everything together in any order::
1478 buffer_pattern=0xdeadface"abcd"-12'filename'
1480 .. option:: dedupe_percentage=int
1482 If set, fio will generate this percentage of identical buffers when
1483 writing. These buffers will be naturally dedupable. The contents of the
1484 buffers depend on what other buffer compression settings have been set. It's
1485 possible to have the individual buffers either fully compressible, or not at
1486 all. This option only controls the distribution of unique buffers.
1488 .. option:: invalidate=bool
1490 Invalidate the buffer/page cache parts of the files to be used prior to
1491 starting I/O if the platform and file type support it. Defaults to true.
1492 This will be ignored if :option:`pre_read` is also specified for the
1495 .. option:: sync=bool
1497 Use synchronous I/O for buffered writes. For the majority of I/O engines,
1498 this means using O_SYNC. Default: false.
1500 .. option:: iomem=str, mem=str
1502 Fio can use various types of memory as the I/O unit buffer. The allowed
1506 Use memory from :manpage:`malloc(3)` as the buffers. Default memory
1510 Use shared memory as the buffers. Allocated through
1511 :manpage:`shmget(2)`.
1514 Same as shm, but use huge pages as backing.
1517 Use :manpage:`mmap(2)` to allocate buffers. May either be anonymous memory, or can
1518 be file backed if a filename is given after the option. The format
1519 is `mem=mmap:/path/to/file`.
1522 Use a memory mapped huge file as the buffer backing. Append filename
1523 after mmaphuge, ala `mem=mmaphuge:/hugetlbfs/file`.
1526 Same as mmap, but use a MMAP_SHARED mapping.
1529 Use GPU memory as the buffers for GPUDirect RDMA benchmark.
1530 The :option:`ioengine` must be `rdma`.
1532 The area allocated is a function of the maximum allowed bs size for the job,
1533 multiplied by the I/O depth given. Note that for **shmhuge** and
1534 **mmaphuge** to work, the system must have free huge pages allocated. This
1535 can normally be checked and set by reading/writing
1536 :file:`/proc/sys/vm/nr_hugepages` on a Linux system. Fio assumes a huge page
1537 is 4MiB in size. So to calculate the number of huge pages you need for a
1538 given job file, add up the I/O depth of all jobs (normally one unless
1539 :option:`iodepth` is used) and multiply by the maximum bs set. Then divide
1540 that number by the huge page size. You can see the size of the huge pages in
1541 :file:`/proc/meminfo`. If no huge pages are allocated by having a non-zero
1542 number in `nr_hugepages`, using **mmaphuge** or **shmhuge** will fail. Also
1543 see :option:`hugepage-size`.
1545 **mmaphuge** also needs to have hugetlbfs mounted and the file location
1546 should point there. So if it's mounted in :file:`/huge`, you would use
1547 `mem=mmaphuge:/huge/somefile`.
1549 .. option:: iomem_align=int, mem_align=int
1551 This indicates the memory alignment of the I/O memory buffers. Note that
1552 the given alignment is applied to the first I/O unit buffer, if using
1553 :option:`iodepth` the alignment of the following buffers are given by the
1554 :option:`bs` used. In other words, if using a :option:`bs` that is a
1555 multiple of the page sized in the system, all buffers will be aligned to
1556 this value. If using a :option:`bs` that is not page aligned, the alignment
1557 of subsequent I/O memory buffers is the sum of the :option:`iomem_align` and
1560 .. option:: hugepage-size=int
1562 Defines the size of a huge page. Must at least be equal to the system
1563 setting, see :file:`/proc/meminfo`. Defaults to 4MiB. Should probably
1564 always be a multiple of megabytes, so using ``hugepage-size=Xm`` is the
1565 preferred way to set this to avoid setting a non-pow-2 bad value.
1567 .. option:: lockmem=int
1569 Pin the specified amount of memory with :manpage:`mlock(2)`. Can be used to
1570 simulate a smaller amount of memory. The amount specified is per worker.
1576 .. option:: size=int
1578 The total size of file I/O for each thread of this job. Fio will run until
1579 this many bytes has been transferred, unless runtime is limited by other options
1580 (such as :option:`runtime`, for instance, or increased/decreased by :option:`io_size`).
1581 Fio will divide this size between the available files determined by options
1582 such as :option:`nrfiles`, :option:`filename`, unless :option:`filesize` is
1583 specified by the job. If the result of division happens to be 0, the size is
1584 set to the physical size of the given files or devices if they exist.
1585 If this option is not specified, fio will use the full size of the given
1586 files or devices. If the files do not exist, size must be given. It is also
1587 possible to give size as a percentage between 1 and 100. If ``size=20%`` is
1588 given, fio will use 20% of the full size of the given files or devices.
1589 Can be combined with :option:`offset` to constrain the start and end range
1590 that I/O will be done within.
1592 .. option:: io_size=int, io_limit=int
1594 Normally fio operates within the region set by :option:`size`, which means
1595 that the :option:`size` option sets both the region and size of I/O to be
1596 performed. Sometimes that is not what you want. With this option, it is
1597 possible to define just the amount of I/O that fio should do. For instance,
1598 if :option:`size` is set to 20GiB and :option:`io_size` is set to 5GiB, fio
1599 will perform I/O within the first 20GiB but exit when 5GiB have been
1600 done. The opposite is also possible -- if :option:`size` is set to 20GiB,
1601 and :option:`io_size` is set to 40GiB, then fio will do 40GiB of I/O within
1602 the 0..20GiB region.
1604 .. option:: filesize=irange(int)
1606 Individual file sizes. May be a range, in which case fio will select sizes
1607 for files at random within the given range and limited to :option:`size` in
1608 total (if that is given). If not given, each created file is the same size.
1609 This option overrides :option:`size` in terms of file size, which means
1610 this value is used as a fixed size or possible range of each file.
1612 .. option:: file_append=bool
1614 Perform I/O after the end of the file. Normally fio will operate within the
1615 size of a file. If this option is set, then fio will append to the file
1616 instead. This has identical behavior to setting :option:`offset` to the size
1617 of a file. This option is ignored on non-regular files.
1619 .. option:: fill_device=bool, fill_fs=bool
1621 Sets size to something really large and waits for ENOSPC (no space left on
1622 device) as the terminating condition. Only makes sense with sequential
1623 write. For a read workload, the mount point will be filled first then I/O
1624 started on the result. This option doesn't make sense if operating on a raw
1625 device node, since the size of that is already known by the file system.
1626 Additionally, writing beyond end-of-device will not return ENOSPC there.
1632 .. option:: ioengine=str
1634 Defines how the job issues I/O to the file. The following types are defined:
1637 Basic :manpage:`read(2)` or :manpage:`write(2)`
1638 I/O. :manpage:`lseek(2)` is used to position the I/O location.
1639 See :option:`fsync` and :option:`fdatasync` for syncing write I/Os.
1642 Basic :manpage:`pread(2)` or :manpage:`pwrite(2)` I/O. Default on
1643 all supported operating systems except for Windows.
1646 Basic :manpage:`readv(2)` or :manpage:`writev(2)` I/O. Will emulate
1647 queuing by coalescing adjacent I/Os into a single submission.
1650 Basic :manpage:`preadv(2)` or :manpage:`pwritev(2)` I/O.
1653 Basic :manpage:`preadv2(2)` or :manpage:`pwritev2(2)` I/O.
1656 Linux native asynchronous I/O. Note that Linux may only support
1657 queued behavior with non-buffered I/O (set ``direct=1`` or
1659 This engine defines engine specific options.
1662 POSIX asynchronous I/O using :manpage:`aio_read(3)` and
1663 :manpage:`aio_write(3)`.
1666 Solaris native asynchronous I/O.
1669 Windows native asynchronous I/O. Default on Windows.
1672 File is memory mapped with :manpage:`mmap(2)` and data copied
1673 to/from using :manpage:`memcpy(3)`.
1676 :manpage:`splice(2)` is used to transfer the data and
1677 :manpage:`vmsplice(2)` to transfer data from user space to the
1681 SCSI generic sg v3 I/O. May either be synchronous using the SG_IO
1682 ioctl, or if the target is an sg character device we use
1683 :manpage:`read(2)` and :manpage:`write(2)` for asynchronous
1684 I/O. Requires :option:`filename` option to specify either block or
1688 Doesn't transfer any data, just pretends to. This is mainly used to
1689 exercise fio itself and for debugging/testing purposes.
1692 Transfer over the network to given ``host:port``. Depending on the
1693 :option:`protocol` used, the :option:`hostname`, :option:`port`,
1694 :option:`listen` and :option:`filename` options are used to specify
1695 what sort of connection to make, while the :option:`protocol` option
1696 determines which protocol will be used. This engine defines engine
1700 Like **net**, but uses :manpage:`splice(2)` and
1701 :manpage:`vmsplice(2)` to map data and send/receive.
1702 This engine defines engine specific options.
1705 Doesn't transfer any data, but burns CPU cycles according to the
1706 :option:`cpuload` and :option:`cpuchunks` options. Setting
1707 :option:`cpuload`\=85 will cause that job to do nothing but burn 85%
1708 of the CPU. In case of SMP machines, use :option:`numjobs`=<nr_of_cpu>
1709 to get desired CPU usage, as the cpuload only loads a
1710 single CPU at the desired rate. A job never finishes unless there is
1711 at least one non-cpuio job.
1714 The GUASI I/O engine is the Generic Userspace Asyncronous Syscall
1715 Interface approach to async I/O. See
1717 http://www.xmailserver.org/guasi-lib.html
1719 for more info on GUASI.
1722 The RDMA I/O engine supports both RDMA memory semantics
1723 (RDMA_WRITE/RDMA_READ) and channel semantics (Send/Recv) for the
1724 InfiniBand, RoCE and iWARP protocols.
1727 I/O engine that does regular fallocate to simulate data transfer as
1731 does fallocate(,mode = FALLOC_FL_KEEP_SIZE,).
1734 does fallocate(,mode = 0).
1737 does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE).
1740 I/O engine that sends :manpage:`ftruncate(2)` operations in response
1741 to write (DDIR_WRITE) events. Each ftruncate issued sets the file's
1742 size to the current block offset. :option:`blocksize` is ignored.
1745 I/O engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate
1746 defragment activity in request to DDIR_WRITE event.
1749 I/O engine supporting direct access to Ceph Rados Block Devices
1750 (RBD) via librbd without the need to use the kernel rbd driver. This
1751 ioengine defines engine specific options.
1754 Using GlusterFS libgfapi sync interface to direct access to
1755 GlusterFS volumes without having to go through FUSE. This ioengine
1756 defines engine specific options.
1759 Using GlusterFS libgfapi async interface to direct access to
1760 GlusterFS volumes without having to go through FUSE. This ioengine
1761 defines engine specific options.
1764 Read and write through Hadoop (HDFS). The :option:`filename` option
1765 is used to specify host,port of the hdfs name-node to connect. This
1766 engine interprets offsets a little differently. In HDFS, files once
1767 created cannot be modified so random writes are not possible. To
1768 imitate this the libhdfs engine expects a bunch of small files to be
1769 created over HDFS and will randomly pick a file from them
1770 based on the offset generated by fio backend (see the example
1771 job file to create such files, use ``rw=write`` option). Please
1772 note, it may be necessary to set environment variables to work
1773 with HDFS/libhdfs properly. Each job uses its own connection to
1777 Read, write and erase an MTD character device (e.g.,
1778 :file:`/dev/mtd0`). Discards are treated as erases. Depending on the
1779 underlying device type, the I/O may have to go in a certain pattern,
1780 e.g., on NAND, writing sequentially to erase blocks and discarding
1781 before overwriting. The `trimwrite` mode works well for this
1785 Read and write using filesystem DAX to a file on a filesystem
1786 mounted with DAX on a persistent memory device through the NVML
1790 Read and write using device DAX to a persistent memory device (e.g.,
1791 /dev/dax0.0) through the NVML libpmem library.
1794 Prefix to specify loading an external I/O engine object file. Append
1795 the engine filename, e.g. ``ioengine=external:/tmp/foo.o`` to load
1796 ioengine :file:`foo.o` in :file:`/tmp`. The path can be either
1797 absolute or relative. See :file:`engines/skeleton_external.c` for
1798 details of writing an external I/O engine.
1801 I/O engine specific parameters
1802 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1804 In addition, there are some parameters which are only valid when a specific
1805 :option:`ioengine` is in use. These are used identically to normal parameters,
1806 with the caveat that when used on the command line, they must come after the
1807 :option:`ioengine` that defines them is selected.
1809 .. option:: userspace_reap : [libaio]
1811 Normally, with the libaio engine in use, fio will use the
1812 :manpage:`io_getevents(2)` system call to reap newly returned events. With
1813 this flag turned on, the AIO ring will be read directly from user-space to
1814 reap events. The reaping mode is only enabled when polling for a minimum of
1815 0 events (e.g. when :option:`iodepth_batch_complete` `=0`).
1817 .. option:: hipri : [pvsync2]
1819 Set RWF_HIPRI on I/O, indicating to the kernel that it's of higher priority
1822 .. option:: hipri_percentage : [pvsync2]
1824 When hipri is set this determines the probability of a pvsync2 I/O being high
1825 priority. The default is 100%.
1827 .. option:: cpuload=int : [cpuio]
1829 Attempt to use the specified percentage of CPU cycles. This is a mandatory
1830 option when using cpuio I/O engine.
1832 .. option:: cpuchunks=int : [cpuio]
1834 Split the load into cycles of the given time. In microseconds.
1836 .. option:: exit_on_io_done=bool : [cpuio]
1838 Detect when I/O threads are done, then exit.
1840 .. option:: namenode=str : [libhdfs]
1842 The hostname or IP address of a HDFS cluster namenode to contact.
1844 .. option:: port=int
1848 The listening port of the HFDS cluster namenode.
1852 The TCP or UDP port to bind to or connect to. If this is used with
1853 :option:`numjobs` to spawn multiple instances of the same job type, then
1854 this will be the starting port number since fio will use a range of
1857 .. option:: hostname=str : [netsplice] [net]
1859 The hostname or IP address to use for TCP or UDP based I/O. If the job is
1860 a TCP listener or UDP reader, the hostname is not used and must be omitted
1861 unless it is a valid UDP multicast address.
1863 .. option:: interface=str : [netsplice] [net]
1865 The IP address of the network interface used to send or receive UDP
1868 .. option:: ttl=int : [netsplice] [net]
1870 Time-to-live value for outgoing UDP multicast packets. Default: 1.
1872 .. option:: nodelay=bool : [netsplice] [net]
1874 Set TCP_NODELAY on TCP connections.
1876 .. option:: protocol=str, proto=str : [netsplice] [net]
1878 The network protocol to use. Accepted values are:
1881 Transmission control protocol.
1883 Transmission control protocol V6.
1885 User datagram protocol.
1887 User datagram protocol V6.
1891 When the protocol is TCP or UDP, the port must also be given, as well as the
1892 hostname if the job is a TCP listener or UDP reader. For unix sockets, the
1893 normal :option:`filename` option should be used and the port is invalid.
1895 .. option:: listen : [netsplice] [net]
1897 For TCP network connections, tell fio to listen for incoming connections
1898 rather than initiating an outgoing connection. The :option:`hostname` must
1899 be omitted if this option is used.
1901 .. option:: pingpong : [netsplice] [net]
1903 Normally a network writer will just continue writing data, and a network
1904 reader will just consume packages. If ``pingpong=1`` is set, a writer will
1905 send its normal payload to the reader, then wait for the reader to send the
1906 same payload back. This allows fio to measure network latencies. The
1907 submission and completion latencies then measure local time spent sending or
1908 receiving, and the completion latency measures how long it took for the
1909 other end to receive and send back. For UDP multicast traffic
1910 ``pingpong=1`` should only be set for a single reader when multiple readers
1911 are listening to the same address.
1913 .. option:: window_size : [netsplice] [net]
1915 Set the desired socket buffer size for the connection.
1917 .. option:: mss : [netsplice] [net]
1919 Set the TCP maximum segment size (TCP_MAXSEG).
1921 .. option:: donorname=str : [e4defrag]
1923 File will be used as a block donor (swap extents between files).
1925 .. option:: inplace=int : [e4defrag]
1927 Configure donor file blocks allocation strategy:
1930 Default. Preallocate donor's file on init.
1932 Allocate space immediately inside defragment event, and free right
1935 .. option:: clustername=str : [rbd]
1937 Specifies the name of the Ceph cluster.
1939 .. option:: rbdname=str : [rbd]
1941 Specifies the name of the RBD.
1943 .. option:: pool=str : [rbd]
1945 Specifies the name of the Ceph pool containing RBD.
1947 .. option:: clientname=str : [rbd]
1949 Specifies the username (without the 'client.' prefix) used to access the
1950 Ceph cluster. If the *clustername* is specified, the *clientname* shall be
1951 the full *type.id* string. If no type. prefix is given, fio will add
1952 'client.' by default.
1954 .. option:: skip_bad=bool : [mtd]
1956 Skip operations against known bad blocks.
1958 .. option:: hdfsdirectory : [libhdfs]
1960 libhdfs will create chunk in this HDFS directory.
1962 .. option:: chunk_size : [libhdfs]
1964 The size of the chunk to use for each file.
1970 .. option:: iodepth=int
1972 Number of I/O units to keep in flight against the file. Note that
1973 increasing *iodepth* beyond 1 will not affect synchronous ioengines (except
1974 for small degrees when :option:`verify_async` is in use). Even async
1975 engines may impose OS restrictions causing the desired depth not to be
1976 achieved. This may happen on Linux when using libaio and not setting
1977 :option:`direct`\=1, since buffered I/O is not async on that OS. Keep an
1978 eye on the I/O depth distribution in the fio output to verify that the
1979 achieved depth is as expected. Default: 1.
1981 .. option:: iodepth_batch_submit=int, iodepth_batch=int
1983 This defines how many pieces of I/O to submit at once. It defaults to 1
1984 which means that we submit each I/O as soon as it is available, but can be
1985 raised to submit bigger batches of I/O at the time. If it is set to 0 the
1986 :option:`iodepth` value will be used.
1988 .. option:: iodepth_batch_complete_min=int, iodepth_batch_complete=int
1990 This defines how many pieces of I/O to retrieve at once. It defaults to 1
1991 which means that we'll ask for a minimum of 1 I/O in the retrieval process
1992 from the kernel. The I/O retrieval will go on until we hit the limit set by
1993 :option:`iodepth_low`. If this variable is set to 0, then fio will always
1994 check for completed events before queuing more I/O. This helps reduce I/O
1995 latency, at the cost of more retrieval system calls.
1997 .. option:: iodepth_batch_complete_max=int
1999 This defines maximum pieces of I/O to retrieve at once. This variable should
2000 be used along with :option:`iodepth_batch_complete_min`\=int variable,
2001 specifying the range of min and max amount of I/O which should be
2002 retrieved. By default it is equal to the :option:`iodepth_batch_complete_min`
2007 iodepth_batch_complete_min=1
2008 iodepth_batch_complete_max=<iodepth>
2010 which means that we will retrieve at least 1 I/O and up to the whole
2011 submitted queue depth. If none of I/O has been completed yet, we will wait.
2015 iodepth_batch_complete_min=0
2016 iodepth_batch_complete_max=<iodepth>
2018 which means that we can retrieve up to the whole submitted queue depth, but
2019 if none of I/O has been completed yet, we will NOT wait and immediately exit
2020 the system call. In this example we simply do polling.
2022 .. option:: iodepth_low=int
2024 The low water mark indicating when to start filling the queue
2025 again. Defaults to the same as :option:`iodepth`, meaning that fio will
2026 attempt to keep the queue full at all times. If :option:`iodepth` is set to
2027 e.g. 16 and *iodepth_low* is set to 4, then after fio has filled the queue of
2028 16 requests, it will let the depth drain down to 4 before starting to fill
2031 .. option:: serialize_overlap=bool
2033 Serialize in-flight I/Os that might otherwise cause or suffer from data races.
2034 When two or more I/Os are submitted simultaneously, there is no guarantee that
2035 the I/Os will be processed or completed in the submitted order. Further, if
2036 two or more of those I/Os are writes, any overlapping region between them can
2037 become indeterminate/undefined on certain storage. These issues can cause
2038 verification to fail erratically when at least one of the racing I/Os is
2039 changing data and the overlapping region has a non-zero size. Setting
2040 ``serialize_overlap`` tells fio to avoid provoking this behavior by explicitly
2041 serializing in-flight I/Os that have a non-zero overlap. Note that setting
2042 this option can reduce both performance and the `:option:iodepth` achieved.
2043 Additionally this option does not work when :option:`io_submit_mode` is set to
2044 offload. Default: false.
2046 .. option:: io_submit_mode=str
2048 This option controls how fio submits the I/O to the I/O engine. The default
2049 is `inline`, which means that the fio job threads submit and reap I/O
2050 directly. If set to `offload`, the job threads will offload I/O submission
2051 to a dedicated pool of I/O threads. This requires some coordination and thus
2052 has a bit of extra overhead, especially for lower queue depth I/O where it
2053 can increase latencies. The benefit is that fio can manage submission rates
2054 independently of the device completion rates. This avoids skewed latency
2055 reporting if I/O gets backed up on the device side (the coordinated omission
2062 .. option:: thinktime=time
2064 Stall the job for the specified period of time after an I/O has completed before issuing the
2065 next. May be used to simulate processing being done by an application.
2066 When the unit is omitted, the value is interpreted in microseconds. See
2067 :option:`thinktime_blocks` and :option:`thinktime_spin`.
2069 .. option:: thinktime_spin=time
2071 Only valid if :option:`thinktime` is set - pretend to spend CPU time doing
2072 something with the data received, before falling back to sleeping for the
2073 rest of the period specified by :option:`thinktime`. When the unit is
2074 omitted, the value is interpreted in microseconds.
2076 .. option:: thinktime_blocks=int
2078 Only valid if :option:`thinktime` is set - control how many blocks to issue,
2079 before waiting :option:`thinktime` usecs. If not set, defaults to 1 which will make
2080 fio wait :option:`thinktime` usecs after every block. This effectively makes any
2081 queue depth setting redundant, since no more than 1 I/O will be queued
2082 before we have to complete it and do our :option:`thinktime`. In other words, this
2083 setting effectively caps the queue depth if the latter is larger.
2085 .. option:: rate=int[,int][,int]
2087 Cap the bandwidth used by this job. The number is in bytes/sec, the normal
2088 suffix rules apply. Comma-separated values may be specified for reads,
2089 writes, and trims as described in :option:`blocksize`.
2091 For example, using `rate=1m,500k` would limit reads to 1MiB/sec and writes to
2092 500KiB/sec. Capping only reads or writes can be done with `rate=,500k` or
2093 `rate=500k,` where the former will only limit writes (to 500KiB/sec) and the
2094 latter will only limit reads.
2096 .. option:: rate_min=int[,int][,int]
2098 Tell fio to do whatever it can to maintain at least this bandwidth. Failing
2099 to meet this requirement will cause the job to exit. Comma-separated values
2100 may be specified for reads, writes, and trims as described in
2101 :option:`blocksize`.
2103 .. option:: rate_iops=int[,int][,int]
2105 Cap the bandwidth to this number of IOPS. Basically the same as
2106 :option:`rate`, just specified independently of bandwidth. If the job is
2107 given a block size range instead of a fixed value, the smallest block size
2108 is used as the metric. Comma-separated values may be specified for reads,
2109 writes, and trims as described in :option:`blocksize`.
2111 .. option:: rate_iops_min=int[,int][,int]
2113 If fio doesn't meet this rate of I/O, it will cause the job to exit.
2114 Comma-separated values may be specified for reads, writes, and trims as
2115 described in :option:`blocksize`.
2117 .. option:: rate_process=str
2119 This option controls how fio manages rated I/O submissions. The default is
2120 `linear`, which submits I/O in a linear fashion with fixed delays between
2121 I/Os that gets adjusted based on I/O completion rates. If this is set to
2122 `poisson`, fio will submit I/O based on a more real world random request
2123 flow, known as the Poisson process
2124 (https://en.wikipedia.org/wiki/Poisson_point_process). The lambda will be
2125 10^6 / IOPS for the given workload.
2131 .. option:: latency_target=time
2133 If set, fio will attempt to find the max performance point that the given
2134 workload will run at while maintaining a latency below this target. When
2135 the unit is omitted, the value is interpreted in microseconds. See
2136 :option:`latency_window` and :option:`latency_percentile`.
2138 .. option:: latency_window=time
2140 Used with :option:`latency_target` to specify the sample window that the job
2141 is run at varying queue depths to test the performance. When the unit is
2142 omitted, the value is interpreted in microseconds.
2144 .. option:: latency_percentile=float
2146 The percentage of I/Os that must fall within the criteria specified by
2147 :option:`latency_target` and :option:`latency_window`. If not set, this
2148 defaults to 100.0, meaning that all I/Os must be equal or below to the value
2149 set by :option:`latency_target`.
2151 .. option:: max_latency=time
2153 If set, fio will exit the job with an ETIMEDOUT error if it exceeds this
2154 maximum latency. When the unit is omitted, the value is interpreted in
2157 .. option:: rate_cycle=int
2159 Average bandwidth for :option:`rate` and :option:`rate_min` over this number
2160 of milliseconds. Defaults to 1000.
2166 .. option:: write_iolog=str
2168 Write the issued I/O patterns to the specified file. See
2169 :option:`read_iolog`. Specify a separate file for each job, otherwise the
2170 iologs will be interspersed and the file may be corrupt.
2172 .. option:: read_iolog=str
2174 Open an iolog with the specified filename and replay the I/O patterns it
2175 contains. This can be used to store a workload and replay it sometime
2176 later. The iolog given may also be a blktrace binary file, which allows fio
2177 to replay a workload captured by :command:`blktrace`. See
2178 :manpage:`blktrace(8)` for how to capture such logging data. For blktrace
2179 replay, the file needs to be turned into a blkparse binary data file first
2180 (``blkparse <device> -o /dev/null -d file_for_fio.bin``).
2182 .. option:: replay_no_stall=bool
2184 When replaying I/O with :option:`read_iolog` the default behavior is to
2185 attempt to respect the timestamps within the log and replay them with the
2186 appropriate delay between IOPS. By setting this variable fio will not
2187 respect the timestamps and attempt to replay them as fast as possible while
2188 still respecting ordering. The result is the same I/O pattern to a given
2189 device, but different timings.
2191 .. option:: replay_redirect=str
2193 While replaying I/O patterns using :option:`read_iolog` the default behavior
2194 is to replay the IOPS onto the major/minor device that each IOP was recorded
2195 from. This is sometimes undesirable because on a different machine those
2196 major/minor numbers can map to a different device. Changing hardware on the
2197 same system can also result in a different major/minor mapping.
2198 ``replay_redirect`` causes all I/Os to be replayed onto the single specified
2199 device regardless of the device it was recorded
2200 from. i.e. :option:`replay_redirect`\= :file:`/dev/sdc` would cause all I/O
2201 in the blktrace or iolog to be replayed onto :file:`/dev/sdc`. This means
2202 multiple devices will be replayed onto a single device, if the trace
2203 contains multiple devices. If you want multiple devices to be replayed
2204 concurrently to multiple redirected devices you must blkparse your trace
2205 into separate traces and replay them with independent fio invocations.
2206 Unfortunately this also breaks the strict time ordering between multiple
2209 .. option:: replay_align=int
2211 Force alignment of I/O offsets and lengths in a trace to this power of 2
2214 .. option:: replay_scale=int
2216 Scale sector offsets down by this factor when replaying traces.
2219 Threads, processes and job synchronization
2220 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2224 Fio defaults to creating jobs by using fork, however if this option is
2225 given, fio will create jobs by using POSIX Threads' function
2226 :manpage:`pthread_create(3)` to create threads instead.
2228 .. option:: wait_for=str
2230 If set, the current job won't be started until all workers of the specified
2231 waitee job are done.
2233 ``wait_for`` operates on the job name basis, so there are a few
2234 limitations. First, the waitee must be defined prior to the waiter job
2235 (meaning no forward references). Second, if a job is being referenced as a
2236 waitee, it must have a unique name (no duplicate waitees).
2238 .. option:: nice=int
2240 Run the job with the given nice value. See man :manpage:`nice(2)`.
2242 On Windows, values less than -15 set the process class to "High"; -1 through
2243 -15 set "Above Normal"; 1 through 15 "Below Normal"; and above 15 "Idle"
2246 .. option:: prio=int
2248 Set the I/O priority value of this job. Linux limits us to a positive value
2249 between 0 and 7, with 0 being the highest. See man
2250 :manpage:`ionice(1)`. Refer to an appropriate manpage for other operating
2251 systems since meaning of priority may differ.
2253 .. option:: prioclass=int
2255 Set the I/O priority class. See man :manpage:`ionice(1)`.
2257 .. option:: cpumask=int
2259 Set the CPU affinity of this job. The parameter given is a bit mask of
2260 allowed CPUs the job may run on. So if you want the allowed CPUs to be 1
2261 and 5, you would pass the decimal value of (1 << 1 | 1 << 5), or 34. See man
2262 :manpage:`sched_setaffinity(2)`. This may not work on all supported
2263 operating systems or kernel versions. This option doesn't work well for a
2264 higher CPU count than what you can store in an integer mask, so it can only
2265 control cpus 1-32. For boxes with larger CPU counts, use
2266 :option:`cpus_allowed`.
2268 .. option:: cpus_allowed=str
2270 Controls the same options as :option:`cpumask`, but accepts a textual
2271 specification of the permitted CPUs instead. So to use CPUs 1 and 5 you
2272 would specify ``cpus_allowed=1,5``. This option also allows a range of CPUs
2273 to be specified -- say you wanted a binding to CPUs 1, 5, and 8 to 15, you
2274 would set ``cpus_allowed=1,5,8-15``.
2276 .. option:: cpus_allowed_policy=str
2278 Set the policy of how fio distributes the CPUs specified by
2279 :option:`cpus_allowed` or :option:`cpumask`. Two policies are supported:
2282 All jobs will share the CPU set specified.
2284 Each job will get a unique CPU from the CPU set.
2286 **shared** is the default behavior, if the option isn't specified. If
2287 **split** is specified, then fio will will assign one cpu per job. If not
2288 enough CPUs are given for the jobs listed, then fio will roundrobin the CPUs
2291 .. option:: numa_cpu_nodes=str
2293 Set this job running on specified NUMA nodes' CPUs. The arguments allow
2294 comma delimited list of cpu numbers, A-B ranges, or `all`. Note, to enable
2295 NUMA options support, fio must be built on a system with libnuma-dev(el)
2298 .. option:: numa_mem_policy=str
2300 Set this job's memory policy and corresponding NUMA nodes. Format of the
2305 ``mode`` is one of the following memory poicies: ``default``, ``prefer``,
2306 ``bind``, ``interleave`` or ``local``. For ``default`` and ``local`` memory
2307 policies, no node needs to be specified. For ``prefer``, only one node is
2308 allowed. For ``bind`` and ``interleave`` the ``nodelist`` may be as
2309 follows: a comma delimited list of numbers, A-B ranges, or `all`.
2311 .. option:: cgroup=str
2313 Add job to this control group. If it doesn't exist, it will be created. The
2314 system must have a mounted cgroup blkio mount point for this to work. If
2315 your system doesn't have it mounted, you can do so with::
2317 # mount -t cgroup -o blkio none /cgroup
2319 .. option:: cgroup_weight=int
2321 Set the weight of the cgroup to this value. See the documentation that comes
2322 with the kernel, allowed values are in the range of 100..1000.
2324 .. option:: cgroup_nodelete=bool
2326 Normally fio will delete the cgroups it has created after the job
2327 completion. To override this behavior and to leave cgroups around after the
2328 job completion, set ``cgroup_nodelete=1``. This can be useful if one wants
2329 to inspect various cgroup files after job completion. Default: false.
2331 .. option:: flow_id=int
2333 The ID of the flow. If not specified, it defaults to being a global
2334 flow. See :option:`flow`.
2336 .. option:: flow=int
2338 Weight in token-based flow control. If this value is used, then there is a
2339 'flow counter' which is used to regulate the proportion of activity between
2340 two or more jobs. Fio attempts to keep this flow counter near zero. The
2341 ``flow`` parameter stands for how much should be added or subtracted to the
2342 flow counter on each iteration of the main I/O loop. That is, if one job has
2343 ``flow=8`` and another job has ``flow=-1``, then there will be a roughly 1:8
2344 ratio in how much one runs vs the other.
2346 .. option:: flow_watermark=int
2348 The maximum value that the absolute value of the flow counter is allowed to
2349 reach before the job must wait for a lower value of the counter.
2351 .. option:: flow_sleep=int
2353 The period of time, in microseconds, to wait after the flow watermark has
2354 been exceeded before retrying operations.
2356 .. option:: stonewall, wait_for_previous
2358 Wait for preceding jobs in the job file to exit, before starting this
2359 one. Can be used to insert serialization points in the job file. A stone
2360 wall also implies starting a new reporting group, see
2361 :option:`group_reporting`.
2365 By default, fio will continue running all other jobs when one job finishes
2366 but sometimes this is not the desired action. Setting ``exitall`` will
2367 instead make fio terminate all other jobs when one job finishes.
2369 .. option:: exec_prerun=str
2371 Before running this job, issue the command specified through
2372 :manpage:`system(3)`. Output is redirected in a file called
2373 :file:`jobname.prerun.txt`.
2375 .. option:: exec_postrun=str
2377 After the job completes, issue the command specified though
2378 :manpage:`system(3)`. Output is redirected in a file called
2379 :file:`jobname.postrun.txt`.
2383 Instead of running as the invoking user, set the user ID to this value
2384 before the thread/process does any work.
2388 Set group ID, see :option:`uid`.
2394 .. option:: verify_only
2396 Do not perform specified workload, only verify data still matches previous
2397 invocation of this workload. This option allows one to check data multiple
2398 times at a later date without overwriting it. This option makes sense only
2399 for workloads that write data, and does not support workloads with the
2400 :option:`time_based` option set.
2402 .. option:: do_verify=bool
2404 Run the verify phase after a write phase. Only valid if :option:`verify` is
2407 .. option:: verify=str
2409 If writing to a file, fio can verify the file contents after each iteration
2410 of the job. Each verification method also implies verification of special
2411 header, which is written to the beginning of each block. This header also
2412 includes meta information, like offset of the block, block number, timestamp
2413 when block was written, etc. :option:`verify` can be combined with
2414 :option:`verify_pattern` option. The allowed values are:
2417 Use an md5 sum of the data area and store it in the header of
2421 Use an experimental crc64 sum of the data area and store it in the
2422 header of each block.
2425 Use a crc32c sum of the data area and store it in the header of
2426 each block. This will automatically use hardware acceleration
2427 (e.g. SSE4.2 on an x86 or CRC crypto extensions on ARM64) but will
2428 fall back to software crc32c if none is found. Generally the
2429 fatest checksum fio supports when hardware accelerated.
2435 Use a crc32 sum of the data area and store it in the header of each
2439 Use a crc16 sum of the data area and store it in the header of each
2443 Use a crc7 sum of the data area and store it in the header of each
2447 Use xxhash as the checksum function. Generally the fastest software
2448 checksum that fio supports.
2451 Use sha512 as the checksum function.
2454 Use sha256 as the checksum function.
2457 Use optimized sha1 as the checksum function.
2460 Use optimized sha3-224 as the checksum function.
2463 Use optimized sha3-256 as the checksum function.
2466 Use optimized sha3-384 as the checksum function.
2469 Use optimized sha3-512 as the checksum function.
2472 This option is deprecated, since now meta information is included in
2473 generic verification header and meta verification happens by
2474 default. For detailed information see the description of the
2475 :option:`verify` setting. This option is kept because of
2476 compatibility's sake with old configurations. Do not use it.
2479 Verify a strict pattern. Normally fio includes a header with some
2480 basic information and checksumming, but if this option is set, only
2481 the specific pattern set with :option:`verify_pattern` is verified.
2484 Only pretend to verify. Useful for testing internals with
2485 :option:`ioengine`\=null, not for much else.
2487 This option can be used for repeated burn-in tests of a system to make sure
2488 that the written data is also correctly read back. If the data direction
2489 given is a read or random read, fio will assume that it should verify a
2490 previously written file. If the data direction includes any form of write,
2491 the verify will be of the newly written data.
2493 .. option:: verifysort=bool
2495 If true, fio will sort written verify blocks when it deems it faster to read
2496 them back in a sorted manner. This is often the case when overwriting an
2497 existing file, since the blocks are already laid out in the file system. You
2498 can ignore this option unless doing huge amounts of really fast I/O where
2499 the red-black tree sorting CPU time becomes significant. Default: true.
2501 .. option:: verifysort_nr=int
2503 Pre-load and sort verify blocks for a read workload.
2505 .. option:: verify_offset=int
2507 Swap the verification header with data somewhere else in the block before
2508 writing. It is swapped back before verifying.
2510 .. option:: verify_interval=int
2512 Write the verification header at a finer granularity than the
2513 :option:`blocksize`. It will be written for chunks the size of
2514 ``verify_interval``. :option:`blocksize` should divide this evenly.
2516 .. option:: verify_pattern=str
2518 If set, fio will fill the I/O buffers with this pattern. Fio defaults to
2519 filling with totally random bytes, but sometimes it's interesting to fill
2520 with a known pattern for I/O verification purposes. Depending on the width
2521 of the pattern, fio will fill 1/2/3/4 bytes of the buffer at the time (it can
2522 be either a decimal or a hex number). The ``verify_pattern`` if larger than
2523 a 32-bit quantity has to be a hex number that starts with either "0x" or
2524 "0X". Use with :option:`verify`. Also, ``verify_pattern`` supports %o
2525 format, which means that for each block offset will be written and then
2526 verified back, e.g.::
2530 Or use combination of everything::
2532 verify_pattern=0xff%o"abcd"-12
2534 .. option:: verify_fatal=bool
2536 Normally fio will keep checking the entire contents before quitting on a
2537 block verification failure. If this option is set, fio will exit the job on
2538 the first observed failure. Default: false.
2540 .. option:: verify_dump=bool
2542 If set, dump the contents of both the original data block and the data block
2543 we read off disk to files. This allows later analysis to inspect just what
2544 kind of data corruption occurred. Off by default.
2546 .. option:: verify_async=int
2548 Fio will normally verify I/O inline from the submitting thread. This option
2549 takes an integer describing how many async offload threads to create for I/O
2550 verification instead, causing fio to offload the duty of verifying I/O
2551 contents to one or more separate threads. If using this offload option, even
2552 sync I/O engines can benefit from using an :option:`iodepth` setting higher
2553 than 1, as it allows them to have I/O in flight while verifies are running.
2554 Defaults to 0 async threads, i.e. verification is not asynchronous.
2556 .. option:: verify_async_cpus=str
2558 Tell fio to set the given CPU affinity on the async I/O verification
2559 threads. See :option:`cpus_allowed` for the format used.
2561 .. option:: verify_backlog=int
2563 Fio will normally verify the written contents of a job that utilizes verify
2564 once that job has completed. In other words, everything is written then
2565 everything is read back and verified. You may want to verify continually
2566 instead for a variety of reasons. Fio stores the meta data associated with
2567 an I/O block in memory, so for large verify workloads, quite a bit of memory
2568 would be used up holding this meta data. If this option is enabled, fio will
2569 write only N blocks before verifying these blocks.
2571 .. option:: verify_backlog_batch=int
2573 Control how many blocks fio will verify if :option:`verify_backlog` is
2574 set. If not set, will default to the value of :option:`verify_backlog`
2575 (meaning the entire queue is read back and verified). If
2576 ``verify_backlog_batch`` is less than :option:`verify_backlog` then not all
2577 blocks will be verified, if ``verify_backlog_batch`` is larger than
2578 :option:`verify_backlog`, some blocks will be verified more than once.
2580 .. option:: verify_state_save=bool
2582 When a job exits during the write phase of a verify workload, save its
2583 current state. This allows fio to replay up until that point, if the verify
2584 state is loaded for the verify read phase. The format of the filename is,
2587 <type>-<jobname>-<jobindex>-verify.state.
2589 <type> is "local" for a local run, "sock" for a client/server socket
2590 connection, and "ip" (192.168.0.1, for instance) for a networked
2591 client/server connection. Defaults to true.
2593 .. option:: verify_state_load=bool
2595 If a verify termination trigger was used, fio stores the current write state
2596 of each thread. This can be used at verification time so that fio knows how
2597 far it should verify. Without this information, fio will run a full
2598 verification pass, according to the settings in the job file used. Default
2601 .. option:: trim_percentage=int
2603 Number of verify blocks to discard/trim.
2605 .. option:: trim_verify_zero=bool
2607 Verify that trim/discarded blocks are returned as zeros.
2609 .. option:: trim_backlog=int
2611 Trim after this number of blocks are written.
2613 .. option:: trim_backlog_batch=int
2615 Trim this number of I/O blocks.
2617 .. option:: experimental_verify=bool
2619 Enable experimental verification.
2624 .. option:: steadystate=str:float, ss=str:float
2626 Define the criterion and limit for assessing steady state performance. The
2627 first parameter designates the criterion whereas the second parameter sets
2628 the threshold. When the criterion falls below the threshold for the
2629 specified duration, the job will stop. For example, `iops_slope:0.1%` will
2630 direct fio to terminate the job when the least squares regression slope
2631 falls below 0.1% of the mean IOPS. If :option:`group_reporting` is enabled
2632 this will apply to all jobs in the group. Below is the list of available
2633 steady state assessment criteria. All assessments are carried out using only
2634 data from the rolling collection window. Threshold limits can be expressed
2635 as a fixed value or as a percentage of the mean in the collection window.
2638 Collect IOPS data. Stop the job if all individual IOPS measurements
2639 are within the specified limit of the mean IOPS (e.g., ``iops:2``
2640 means that all individual IOPS values must be within 2 of the mean,
2641 whereas ``iops:0.2%`` means that all individual IOPS values must be
2642 within 0.2% of the mean IOPS to terminate the job).
2645 Collect IOPS data and calculate the least squares regression
2646 slope. Stop the job if the slope falls below the specified limit.
2649 Collect bandwidth data. Stop the job if all individual bandwidth
2650 measurements are within the specified limit of the mean bandwidth.
2653 Collect bandwidth data and calculate the least squares regression
2654 slope. Stop the job if the slope falls below the specified limit.
2656 .. option:: steadystate_duration=time, ss_dur=time
2658 A rolling window of this duration will be used to judge whether steady state
2659 has been reached. Data will be collected once per second. The default is 0
2660 which disables steady state detection. When the unit is omitted, the
2661 value is interpreted in seconds.
2663 .. option:: steadystate_ramp_time=time, ss_ramp=time
2665 Allow the job to run for the specified duration before beginning data
2666 collection for checking the steady state job termination criterion. The
2667 default is 0. When the unit is omitted, the value is interpreted in seconds.
2670 Measurements and reporting
2671 ~~~~~~~~~~~~~~~~~~~~~~~~~~
2673 .. option:: per_job_logs=bool
2675 If set, this generates bw/clat/iops log with per file private filenames. If
2676 not set, jobs with identical names will share the log filename. Default:
2679 .. option:: group_reporting
2681 It may sometimes be interesting to display statistics for groups of jobs as
2682 a whole instead of for each individual job. This is especially true if
2683 :option:`numjobs` is used; looking at individual thread/process output
2684 quickly becomes unwieldy. To see the final report per-group instead of
2685 per-job, use :option:`group_reporting`. Jobs in a file will be part of the
2686 same reporting group, unless if separated by a :option:`stonewall`, or by
2687 using :option:`new_group`.
2689 .. option:: new_group
2691 Start a new reporting group. See: :option:`group_reporting`. If not given,
2692 all jobs in a file will be part of the same reporting group, unless
2693 separated by a :option:`stonewall`.
2695 .. option:: stats=bool
2697 By default, fio collects and shows final output results for all jobs
2698 that run. If this option is set to 0, then fio will ignore it in
2699 the final stat output.
2701 .. option:: write_bw_log=str
2703 If given, write a bandwidth log for this job. Can be used to store data of
2704 the bandwidth of the jobs in their lifetime. The included
2705 :command:`fio_generate_plots` script uses :command:`gnuplot` to turn these
2706 text files into nice graphs. See :option:`write_lat_log` for behavior of
2707 given filename. For this option, the postfix is :file:`_bw.x.log`, where `x`
2708 is the index of the job (`1..N`, where `N` is the number of jobs). If
2709 :option:`per_job_logs` is false, then the filename will not include the job
2710 index. See `Log File Formats`_.
2712 .. option:: write_lat_log=str
2714 Same as :option:`write_bw_log`, except that this option stores I/O
2715 submission, completion, and total latencies instead. If no filename is given
2716 with this option, the default filename of :file:`jobname_type.log` is
2717 used. Even if the filename is given, fio will still append the type of
2718 log. So if one specifies::
2722 The actual log names will be :file:`foo_slat.x.log`, :file:`foo_clat.x.log`,
2723 and :file:`foo_lat.x.log`, where `x` is the index of the job (`1..N`, where `N`
2724 is the number of jobs). This helps :command:`fio_generate_plots` find the
2725 logs automatically. If :option:`per_job_logs` is false, then the filename
2726 will not include the job index. See `Log File Formats`_.
2728 .. option:: write_hist_log=str
2730 Same as :option:`write_lat_log`, but writes I/O completion latency
2731 histograms. If no filename is given with this option, the default filename
2732 of :file:`jobname_clat_hist.x.log` is used, where `x` is the index of the
2733 job (`1..N`, where `N` is the number of jobs). Even if the filename is given,
2734 fio will still append the type of log. If :option:`per_job_logs` is false,
2735 then the filename will not include the job index. See `Log File Formats`_.
2737 .. option:: write_iops_log=str
2739 Same as :option:`write_bw_log`, but writes IOPS. If no filename is given
2740 with this option, the default filename of :file:`jobname_type.x.log` is
2741 used, where `x` is the index of the job (`1..N`, where `N` is the number of
2742 jobs). Even if the filename is given, fio will still append the type of
2743 log. If :option:`per_job_logs` is false, then the filename will not include
2744 the job index. See `Log File Formats`_.
2746 .. option:: log_avg_msec=int
2748 By default, fio will log an entry in the iops, latency, or bw log for every
2749 I/O that completes. When writing to the disk log, that can quickly grow to a
2750 very large size. Setting this option makes fio average the each log entry
2751 over the specified period of time, reducing the resolution of the log. See
2752 :option:`log_max_value` as well. Defaults to 0, logging all entries.
2753 Also see `Log File Formats`_.
2755 .. option:: log_hist_msec=int
2757 Same as :option:`log_avg_msec`, but logs entries for completion latency
2758 histograms. Computing latency percentiles from averages of intervals using
2759 :option:`log_avg_msec` is inaccurate. Setting this option makes fio log
2760 histogram entries over the specified period of time, reducing log sizes for
2761 high IOPS devices while retaining percentile accuracy. See
2762 :option:`log_hist_coarseness` as well. Defaults to 0, meaning histogram
2763 logging is disabled.
2765 .. option:: log_hist_coarseness=int
2767 Integer ranging from 0 to 6, defining the coarseness of the resolution of
2768 the histogram logs enabled with :option:`log_hist_msec`. For each increment
2769 in coarseness, fio outputs half as many bins. Defaults to 0, for which
2770 histogram logs contain 1216 latency bins. See `Log File Formats`_.
2772 .. option:: log_max_value=bool
2774 If :option:`log_avg_msec` is set, fio logs the average over that window. If
2775 you instead want to log the maximum value, set this option to 1. Defaults to
2776 0, meaning that averaged values are logged.
2778 .. option:: log_offset=bool
2780 If this is set, the iolog options will include the byte offset for the I/O
2781 entry as well as the other data values. Defaults to 0 meaning that
2782 offsets are not present in logs. Also see `Log File Formats`_.
2784 .. option:: log_compression=int
2786 If this is set, fio will compress the I/O logs as it goes, to keep the
2787 memory footprint lower. When a log reaches the specified size, that chunk is
2788 removed and compressed in the background. Given that I/O logs are fairly
2789 highly compressible, this yields a nice memory savings for longer runs. The
2790 downside is that the compression will consume some background CPU cycles, so
2791 it may impact the run. This, however, is also true if the logging ends up
2792 consuming most of the system memory. So pick your poison. The I/O logs are
2793 saved normally at the end of a run, by decompressing the chunks and storing
2794 them in the specified log file. This feature depends on the availability of
2797 .. option:: log_compression_cpus=str
2799 Define the set of CPUs that are allowed to handle online log compression for
2800 the I/O jobs. This can provide better isolation between performance
2801 sensitive jobs, and background compression work.
2803 .. option:: log_store_compressed=bool
2805 If set, fio will store the log files in a compressed format. They can be
2806 decompressed with fio, using the :option:`--inflate-log` command line
2807 parameter. The files will be stored with a :file:`.fz` suffix.
2809 .. option:: log_unix_epoch=bool
2811 If set, fio will log Unix timestamps to the log files produced by enabling
2812 write_type_log for each log type, instead of the default zero-based
2815 .. option:: block_error_percentiles=bool
2817 If set, record errors in trim block-sized units from writes and trims and
2818 output a histogram of how many trims it took to get to errors, and what kind
2819 of error was encountered.
2821 .. option:: bwavgtime=int
2823 Average the calculated bandwidth over the given time. Value is specified in
2824 milliseconds. If the job also does bandwidth logging through
2825 :option:`write_bw_log`, then the minimum of this option and
2826 :option:`log_avg_msec` will be used. Default: 500ms.
2828 .. option:: iopsavgtime=int
2830 Average the calculated IOPS over the given time. Value is specified in
2831 milliseconds. If the job also does IOPS logging through
2832 :option:`write_iops_log`, then the minimum of this option and
2833 :option:`log_avg_msec` will be used. Default: 500ms.
2835 .. option:: disk_util=bool
2837 Generate disk utilization statistics, if the platform supports it.
2840 .. option:: disable_lat=bool
2842 Disable measurements of total latency numbers. Useful only for cutting back
2843 the number of calls to :manpage:`gettimeofday(2)`, as that does impact
2844 performance at really high IOPS rates. Note that to really get rid of a
2845 large amount of these calls, this option must be used with
2846 :option:`disable_slat` and :option:`disable_bw_measurement` as well.
2848 .. option:: disable_clat=bool
2850 Disable measurements of completion latency numbers. See
2851 :option:`disable_lat`.
2853 .. option:: disable_slat=bool
2855 Disable measurements of submission latency numbers. See
2856 :option:`disable_lat`.
2858 .. option:: disable_bw_measurement=bool, disable_bw=bool
2860 Disable measurements of throughput/bandwidth numbers. See
2861 :option:`disable_lat`.
2863 .. option:: clat_percentiles=bool
2865 Enable the reporting of percentiles of completion latencies. This
2866 option is mutually exclusive with :option:`lat_percentiles`.
2868 .. option:: lat_percentiles=bool
2870 Enable the reporting of percentiles of IO latencies. This is similar
2871 to :option:`clat_percentiles`, except that this includes the
2872 submission latency. This option is mutually exclusive with
2873 :option:`clat_percentiles`.
2875 .. option:: percentile_list=float_list
2877 Overwrite the default list of percentiles for completion latencies and the
2878 block error histogram. Each number is a floating number in the range
2879 (0,100], and the maximum length of the list is 20. Use ``:`` to separate the
2880 numbers, and list the numbers in ascending order. For example,
2881 ``--percentile_list=99.5:99.9`` will cause fio to report the values of
2882 completion latency below which 99.5% and 99.9% of the observed latencies
2889 .. option:: exitall_on_error
2891 When one job finishes in error, terminate the rest. The default is to wait
2892 for each job to finish.
2894 .. option:: continue_on_error=str
2896 Normally fio will exit the job on the first observed failure. If this option
2897 is set, fio will continue the job when there is a 'non-fatal error' (EIO or
2898 EILSEQ) until the runtime is exceeded or the I/O size specified is
2899 completed. If this option is used, there are two more stats that are
2900 appended, the total error count and the first error. The error field given
2901 in the stats is the first error that was hit during the run.
2903 The allowed values are:
2906 Exit on any I/O or verify errors.
2909 Continue on read errors, exit on all others.
2912 Continue on write errors, exit on all others.
2915 Continue on any I/O error, exit on all others.
2918 Continue on verify errors, exit on all others.
2921 Continue on all errors.
2924 Backward-compatible alias for 'none'.
2927 Backward-compatible alias for 'all'.
2929 .. option:: ignore_error=str
2931 Sometimes you want to ignore some errors during test in that case you can
2932 specify error list for each error type, instead of only being able to
2933 ignore the default 'non-fatal error' using :option:`continue_on_error`.
2934 ``ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST`` errors for
2935 given error type is separated with ':'. Error may be symbol ('ENOSPC',
2936 'ENOMEM') or integer. Example::
2938 ignore_error=EAGAIN,ENOSPC:122
2940 This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from
2941 WRITE. This option works by overriding :option:`continue_on_error` with
2942 the list of errors for each error type if any.
2944 .. option:: error_dump=bool
2946 If set dump every error even if it is non fatal, true by default. If
2947 disabled only fatal error will be dumped.
2949 Running predefined workloads
2950 ----------------------------
2952 Fio includes predefined profiles that mimic the I/O workloads generated by
2955 .. option:: profile=str
2957 The predefined workload to run. Current profiles are:
2960 Threaded I/O bench (tiotest/tiobench) like workload.
2963 Aerospike Certification Tool (ACT) like workload.
2965 To view a profile's additional options use :option:`--cmdhelp` after specifying
2966 the profile. For example::
2968 $ fio --profile=act --cmdhelp
2973 .. option:: device-names=str
2978 .. option:: load=int
2981 ACT load multiplier. Default: 1.
2983 .. option:: test-duration=time
2986 How long the entire test takes to run. When the unit is omitted, the value
2987 is given in seconds. Default: 24h.
2989 .. option:: threads-per-queue=int
2992 Number of read I/O threads per device. Default: 8.
2994 .. option:: read-req-num-512-blocks=int
2997 Number of 512B blocks to read at the time. Default: 3.
2999 .. option:: large-block-op-kbytes=int
3002 Size of large block ops in KiB (writes). Default: 131072.
3007 Set to run ACT prep phase.
3009 Tiobench profile options
3010 ~~~~~~~~~~~~~~~~~~~~~~~~
3012 .. option:: size=str
3017 .. option:: block=int
3020 Block size in bytes. Default: 4096.
3022 .. option:: numruns=int
3032 .. option:: threads=int
3037 Interpreting the output
3038 -----------------------
3041 Example output was based on the following:
3042 TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --time_based \
3043 --rate=1256k --bs=14K --name=quick --runtime=1s --name=mixed \
3044 --runtime=2m --rw=rw
3046 Fio spits out a lot of output. While running, fio will display the status of the
3047 jobs created. An example of that would be::
3049 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]
3051 The characters inside the first set of square brackets denote the current status of
3052 each thread. The first character is the first job defined in the job file, and so
3053 forth. The possible values (in typical life cycle order) are:
3055 +------+-----+-----------------------------------------------------------+
3057 +======+=====+===========================================================+
3058 | P | | Thread setup, but not started. |
3059 +------+-----+-----------------------------------------------------------+
3060 | C | | Thread created. |
3061 +------+-----+-----------------------------------------------------------+
3062 | I | | Thread initialized, waiting or generating necessary data. |
3063 +------+-----+-----------------------------------------------------------+
3064 | | p | Thread running pre-reading file(s). |
3065 +------+-----+-----------------------------------------------------------+
3066 | | / | Thread is in ramp period. |
3067 +------+-----+-----------------------------------------------------------+
3068 | | R | Running, doing sequential reads. |
3069 +------+-----+-----------------------------------------------------------+
3070 | | r | Running, doing random reads. |
3071 +------+-----+-----------------------------------------------------------+
3072 | | W | Running, doing sequential writes. |
3073 +------+-----+-----------------------------------------------------------+
3074 | | w | Running, doing random writes. |
3075 +------+-----+-----------------------------------------------------------+
3076 | | M | Running, doing mixed sequential reads/writes. |
3077 +------+-----+-----------------------------------------------------------+
3078 | | m | Running, doing mixed random reads/writes. |
3079 +------+-----+-----------------------------------------------------------+
3080 | | D | Running, doing sequential trims. |
3081 +------+-----+-----------------------------------------------------------+
3082 | | d | Running, doing random trims. |
3083 +------+-----+-----------------------------------------------------------+
3084 | | F | Running, currently waiting for :manpage:`fsync(2)`. |
3085 +------+-----+-----------------------------------------------------------+
3086 | | V | Running, doing verification of written data. |
3087 +------+-----+-----------------------------------------------------------+
3088 | f | | Thread finishing. |
3089 +------+-----+-----------------------------------------------------------+
3090 | E | | Thread exited, not reaped by main thread yet. |
3091 +------+-----+-----------------------------------------------------------+
3092 | _ | | Thread reaped. |
3093 +------+-----+-----------------------------------------------------------+
3094 | X | | Thread reaped, exited with an error. |
3095 +------+-----+-----------------------------------------------------------+
3096 | K | | Thread reaped, exited due to signal. |
3097 +------+-----+-----------------------------------------------------------+
3100 Example output was based on the following:
3101 TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --runtime=58m \
3102 --time_based --rate=2512k --bs=256K --numjobs=10 \
3103 --name=readers --rw=read --name=writers --rw=write
3105 Fio will condense the thread string as not to take up more space on the command
3106 line than needed. For instance, if you have 10 readers and 10 writers running,
3107 the output would look like this::
3109 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]
3111 Note that the status string is displayed in order, so it's possible to tell which of
3112 the jobs are currently doing what. In the example above this means that jobs 1--10
3113 are readers and 11--20 are writers.
3115 The other values are fairly self explanatory -- number of threads currently
3116 running and doing I/O, the number of currently open files (f=), the estimated
3117 completion percentage, the rate of I/O since last check (read speed listed first,
3118 then write speed and optionally trim speed) in terms of bandwidth and IOPS,
3119 and time to completion for the current running group. It's impossible to estimate
3120 runtime of the following groups (if any).
3123 Example output was based on the following:
3124 TZ=UTC fio --iodepth=16 --ioengine=posixaio --filename=/tmp/fiofile \
3125 --direct=1 --size=100M --time_based --runtime=50s --rate_iops=89 \
3126 --bs=7K --name=Client1 --rw=write
3128 When fio is done (or interrupted by :kbd:`Ctrl-C`), it will show the data for
3129 each thread, group of threads, and disks in that order. For each overall thread (or
3130 group) the output looks like::
3132 Client1: (groupid=0, jobs=1): err= 0: pid=16109: Sat Jun 24 12:07:54 2017
3133 write: IOPS=88, BW=623KiB/s (638kB/s)(30.4MiB/50032msec)
3134 slat (nsec): min=500, max=145500, avg=8318.00, stdev=4781.50
3135 clat (usec): min=170, max=78367, avg=4019.02, stdev=8293.31
3136 lat (usec): min=174, max=78375, avg=4027.34, stdev=8291.79
3137 clat percentiles (usec):
3138 | 1.00th=[ 302], 5.00th=[ 326], 10.00th=[ 343], 20.00th=[ 363],
3139 | 30.00th=[ 392], 40.00th=[ 404], 50.00th=[ 416], 60.00th=[ 445],
3140 | 70.00th=[ 816], 80.00th=[ 6718], 90.00th=[12911], 95.00th=[21627],
3141 | 99.00th=[43779], 99.50th=[51643], 99.90th=[68682], 99.95th=[72877],
3143 bw ( KiB/s): min= 532, max= 686, per=0.10%, avg=622.87, stdev=24.82, samples= 100
3144 iops : min= 76, max= 98, avg=88.98, stdev= 3.54, samples= 100
3145 lat (usec) : 250=0.04%, 500=64.11%, 750=4.81%, 1000=2.79%
3146 lat (msec) : 2=4.16%, 4=1.84%, 10=4.90%, 20=11.33%, 50=5.37%
3147 lat (msec) : 100=0.65%
3148 cpu : usr=0.27%, sys=0.18%, ctx=12072, majf=0, minf=21
3149 IO depths : 1=85.0%, 2=13.1%, 4=1.8%, 8=0.1%, 16=0.0%, 32=0.0%, >=64=0.0%
3150 submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
3151 complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
3152 issued rwt: total=0,4450,0, short=0,0,0, dropped=0,0,0
3153 latency : target=0, window=0, percentile=100.00%, depth=8
3155 The job name (or first job's name when using :option:`group_reporting`) is printed,
3156 along with the group id, count of jobs being aggregated, last error id seen (which
3157 is 0 when there are no errors), pid/tid of that thread and the time the job/group
3158 completed. Below are the I/O statistics for each data direction performed (showing
3159 writes in the example above). In the order listed, they denote:
3162 The string before the colon shows the I/O direction the statistics
3163 are for. **IOPS** is the average I/Os performed per second. **BW**
3164 is the average bandwidth rate shown as: value in power of 2 format
3165 (value in power of 10 format). The last two values show: (**total
3166 I/O performed** in power of 2 format / **runtime** of that thread).
3169 Submission latency (**min** being the minimum, **max** being the
3170 maximum, **avg** being the average, **stdev** being the standard
3171 deviation). This is the time it took to submit the I/O. For
3172 sync I/O this row is not displayed as the slat is really the
3173 completion latency (since queue/complete is one operation there).
3174 This value can be in nanoseconds, microseconds or milliseconds ---
3175 fio will choose the most appropriate base and print that (in the
3176 example above nanoseconds was the best scale). Note: in :option:`--minimal` mode
3177 latencies are always expressed in microseconds.
3180 Completion latency. Same names as slat, this denotes the time from
3181 submission to completion of the I/O pieces. For sync I/O, clat will
3182 usually be equal (or very close) to 0, as the time from submit to
3183 complete is basically just CPU time (I/O has already been done, see slat
3187 Total latency. Same names as slat and clat, this denotes the time from
3188 when fio created the I/O unit to completion of the I/O operation.
3191 Bandwidth statistics based on samples. Same names as the xlat stats,
3192 but also includes the number of samples taken (**samples**) and an
3193 approximate percentage of total aggregate bandwidth this thread
3194 received in its group (**per**). This last value is only really
3195 useful if the threads in this group are on the same disk, since they
3196 are then competing for disk access.
3199 IOPS statistics based on samples. Same names as bw.
3201 **lat (nsec/usec/msec)**
3202 The distribution of I/O completion latencies. This is the time from when
3203 I/O leaves fio and when it gets completed. Unlike the separate
3204 read/write/trim sections above, the data here and in the remaining
3205 sections apply to all I/Os for the reporting group. 250=0.04% means that
3206 0.04% of the I/Os completed in under 250us. 500=64.11% means that 64.11%
3207 of the I/Os required 250 to 499us for completion.
3210 CPU usage. User and system time, along with the number of context
3211 switches this thread went through, usage of system and user time, and
3212 finally the number of major and minor page faults. The CPU utilization
3213 numbers are averages for the jobs in that reporting group, while the
3214 context and fault counters are summed.
3217 The distribution of I/O depths over the job lifetime. The numbers are
3218 divided into powers of 2 and each entry covers depths from that value
3219 up to those that are lower than the next entry -- e.g., 16= covers
3220 depths from 16 to 31. Note that the range covered by a depth
3221 distribution entry can be different to the range covered by the
3222 equivalent submit/complete distribution entry.
3225 How many pieces of I/O were submitting in a single submit call. Each
3226 entry denotes that amount and below, until the previous entry -- e.g.,
3227 16=100% means that we submitted anywhere between 9 to 16 I/Os per submit
3228 call. Note that the range covered by a submit distribution entry can
3229 be different to the range covered by the equivalent depth distribution
3233 Like the above submit number, but for completions instead.
3236 The number of read/write/trim requests issued, and how many of them were
3240 These values are for `--latency-target` and related options. When
3241 these options are engaged, this section describes the I/O depth required
3242 to meet the specified latency target.
3245 Example output was based on the following:
3246 TZ=UTC fio --ioengine=null --iodepth=2 --size=100M --numjobs=2 \
3247 --rate_process=poisson --io_limit=32M --name=read --bs=128k \
3248 --rate=11M --name=write --rw=write --bs=2k --rate=700k
3250 After each client has been listed, the group statistics are printed. They
3251 will look like this::
3253 Run status group 0 (all jobs):
3254 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
3255 WRITE: bw=1231KiB/s (1261kB/s), 616KiB/s-621KiB/s (630kB/s-636kB/s), io=64.0MiB (67.1MB), run=52747-53223msec
3257 For each data direction it prints:
3260 Aggregate bandwidth of threads in this group followed by the
3261 minimum and maximum bandwidth of all the threads in this group.
3262 Values outside of brackets are power-of-2 format and those
3263 within are the equivalent value in a power-of-10 format.
3265 Aggregate I/O performed of all threads in this group. The
3266 format is the same as bw.
3268 The smallest and longest runtimes of the threads in this group.
3270 And finally, the disk statistics are printed. This is Linux specific. They will look like this::
3272 Disk stats (read/write):
3273 sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00%
3275 Each value is printed for both reads and writes, with reads first. The
3279 Number of I/Os performed by all groups.
3281 Number of merges performed by the I/O scheduler.
3283 Number of ticks we kept the disk busy.
3285 Total time spent in the disk queue.
3287 The disk utilization. A value of 100% means we kept the disk
3288 busy constantly, 50% would be a disk idling half of the time.
3290 It is also possible to get fio to dump the current output while it is running,
3291 without terminating the job. To do that, send fio the **USR1** signal. You can
3292 also get regularly timed dumps by using the :option:`--status-interval`
3293 parameter, or by creating a file in :file:`/tmp` named
3294 :file:`fio-dump-status`. If fio sees this file, it will unlink it and dump the
3295 current output status.
3301 For scripted usage where you typically want to generate tables or graphs of the
3302 results, fio can output the results in a semicolon separated format. The format
3303 is one long line of values, such as::
3305 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%
3306 A description of this job goes here.
3308 The job description (if provided) follows on a second line.
3310 To enable terse output, use the :option:`--minimal` or
3311 :option:`--output-format`\=terse command line options. The
3312 first value is the version of the terse output format. If the output has to be
3313 changed for some reason, this number will be incremented by 1 to signify that
3316 Split up, the format is as follows (comments in brackets denote when a
3317 field was introduced or whether it's specific to some terse version):
3321 terse version, fio version [v3], jobname, groupid, error
3325 Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
3326 Submission latency: min, max, mean, stdev (usec)
3327 Completion latency: min, max, mean, stdev (usec)
3328 Completion latency percentiles: 20 fields (see below)
3329 Total latency: min, max, mean, stdev (usec)
3330 Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
3331 IOPS [v5]: min, max, mean, stdev, number of samples
3337 Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
3338 Submission latency: min, max, mean, stdev (usec)
3339 Completion latency: min, max, mean, stdev (usec)
3340 Completion latency percentiles: 20 fields (see below)
3341 Total latency: min, max, mean, stdev (usec)
3342 Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
3343 IOPS [v5]: min, max, mean, stdev, number of samples
3345 TRIM status [all but version 3]:
3347 Fields are similar to READ/WRITE status.
3351 user, system, context switches, major faults, minor faults
3355 <=1, 2, 4, 8, 16, 32, >=64
3357 I/O latencies microseconds::
3359 <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
3361 I/O latencies milliseconds::
3363 <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
3365 Disk utilization [v3]::
3367 disk name, read ios, write ios, read merges, write merges, read ticks, write ticks,
3368 time spent in queue, disk utilization percentage
3370 Additional Info (dependent on continue_on_error, default off)::
3372 total # errors, first error code
3374 Additional Info (dependent on description being set)::
3378 Completion latency percentiles can be a grouping of up to 20 sets, so for the
3379 terse output fio writes all of them. Each field will look like this::
3383 which is the Xth percentile, and the `usec` latency associated with it.
3385 For `Disk utilization`, all disks used by fio are shown. So for each disk there
3386 will be a disk utilization section.
3388 Below is a single line containing short names for each of the fields in the
3389 minimal output v3, separated by semicolons::
3391 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
3397 The `json` output format is intended to be both human readable and convenient
3398 for automated parsing. For the most part its sections mirror those of the
3399 `normal` output. The `runtime` value is reported in msec and the `bw` value is
3400 reported in 1024 bytes per second units.
3406 The `json+` output format is identical to the `json` output format except that it
3407 adds a full dump of the completion latency bins. Each `bins` object contains a
3408 set of (key, value) pairs where keys are latency durations and values count how
3409 many I/Os had completion latencies of the corresponding duration. For example,
3412 "bins" : { "87552" : 1, "89600" : 1, "94720" : 1, "96768" : 1, "97792" : 1, "99840" : 1, "100864" : 2, "103936" : 6, "104960" : 534, "105984" : 5995, "107008" : 7529, ... }
3414 This data indicates that one I/O required 87,552ns to complete, two I/Os required
3415 100,864ns to complete, and 7529 I/Os required 107,008ns to complete.
3417 Also included with fio is a Python script `fio_jsonplus_clat2csv` that takes
3418 json+ output and generates CSV-formatted latency data suitable for plotting.
3420 The latency durations actually represent the midpoints of latency intervals.
3421 For details refer to :file:`stat.h`.
3427 There are two trace file format that you can encounter. The older (v1) format is
3428 unsupported since version 1.20-rc3 (March 2008). It will still be described
3429 below in case that you get an old trace and want to understand it.
3431 In any case the trace is a simple text file with a single action per line.
3434 Trace file format v1
3435 ~~~~~~~~~~~~~~~~~~~~
3437 Each line represents a single I/O action in the following format::
3441 where `rw=0/1` for read/write, and the `offset` and `length` entries being in bytes.
3443 This format is not supported in fio versions >= 1.20-rc3.
3446 Trace file format v2
3447 ~~~~~~~~~~~~~~~~~~~~
3449 The second version of the trace file format was added in fio version 1.17. It
3450 allows to access more then one file per trace and has a bigger set of possible
3453 The first line of the trace file has to be::
3457 Following this can be lines in two different formats, which are described below.
3459 The file management format::
3463 The `filename` is given as an absolute path. The `action` can be one of these:
3466 Add the given `filename` to the trace.
3468 Open the file with the given `filename`. The `filename` has to have
3469 been added with the **add** action before.
3471 Close the file with the given `filename`. The file has to have been
3475 The file I/O action format::
3477 filename action offset length
3479 The `filename` is given as an absolute path, and has to have been added and
3480 opened before it can be used with this format. The `offset` and `length` are
3481 given in bytes. The `action` can be one of these:
3484 Wait for `offset` microseconds. Everything below 100 is discarded.
3485 The time is relative to the previous `wait` statement.
3487 Read `length` bytes beginning from `offset`.
3489 Write `length` bytes beginning from `offset`.
3491 :manpage:`fsync(2)` the file.
3493 :manpage:`fdatasync(2)` the file.
3495 Trim the given file from the given `offset` for `length` bytes.
3497 CPU idleness profiling
3498 ----------------------
3500 In some cases, we want to understand CPU overhead in a test. For example, we
3501 test patches for the specific goodness of whether they reduce CPU usage.
3502 Fio implements a balloon approach to create a thread per CPU that runs at idle
3503 priority, meaning that it only runs when nobody else needs the cpu.
3504 By measuring the amount of work completed by the thread, idleness of each CPU
3505 can be derived accordingly.
3507 An unit work is defined as touching a full page of unsigned characters. Mean and
3508 standard deviation of time to complete an unit work is reported in "unit work"
3509 section. Options can be chosen to report detailed percpu idleness or overall
3510 system idleness by aggregating percpu stats.
3513 Verification and triggers
3514 -------------------------
3516 Fio is usually run in one of two ways, when data verification is done. The first
3517 is a normal write job of some sort with verify enabled. When the write phase has
3518 completed, fio switches to reads and verifies everything it wrote. The second
3519 model is running just the write phase, and then later on running the same job
3520 (but with reads instead of writes) to repeat the same I/O patterns and verify
3521 the contents. Both of these methods depend on the write phase being completed,
3522 as fio otherwise has no idea how much data was written.
3524 With verification triggers, fio supports dumping the current write state to
3525 local files. Then a subsequent read verify workload can load this state and know
3526 exactly where to stop. This is useful for testing cases where power is cut to a
3527 server in a managed fashion, for instance.
3529 A verification trigger consists of two things:
3531 1) Storing the write state of each job.
3532 2) Executing a trigger command.
3534 The write state is relatively small, on the order of hundreds of bytes to single
3535 kilobytes. It contains information on the number of completions done, the last X
3538 A trigger is invoked either through creation ('touch') of a specified file in
3539 the system, or through a timeout setting. If fio is run with
3540 :option:`--trigger-file`\= :file:`/tmp/trigger-file`, then it will continually
3541 check for the existence of :file:`/tmp/trigger-file`. When it sees this file, it
3542 will fire off the trigger (thus saving state, and executing the trigger
3545 For client/server runs, there's both a local and remote trigger. If fio is
3546 running as a server backend, it will send the job states back to the client for
3547 safe storage, then execute the remote trigger, if specified. If a local trigger
3548 is specified, the server will still send back the write state, but the client
3549 will then execute the trigger.
3551 Verification trigger example
3552 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3554 Let's say we want to run a powercut test on the remote Linux machine 'server'.
3555 Our write workload is in :file:`write-test.fio`. We want to cut power to 'server' at
3556 some point during the run, and we'll run this test from the safety or our local
3557 machine, 'localbox'. On the server, we'll start the fio backend normally::
3559 server# fio --server
3561 and on the client, we'll fire off the workload::
3563 localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger-remote="bash -c \"echo b > /proc/sysrq-triger\""
3565 We set :file:`/tmp/my-trigger` as the trigger file, and we tell fio to execute::
3567 echo b > /proc/sysrq-trigger
3569 on the server once it has received the trigger and sent us the write state. This
3570 will work, but it's not **really** cutting power to the server, it's merely
3571 abruptly rebooting it. If we have a remote way of cutting power to the server
3572 through IPMI or similar, we could do that through a local trigger command
3573 instead. Let's assume we have a script that does IPMI reboot of a given hostname,
3574 ipmi-reboot. On localbox, we could then have run fio with a local trigger
3577 localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger="ipmi-reboot server"
3579 For this case, fio would wait for the server to send us the write state, then
3580 execute ``ipmi-reboot server`` when that happened.
3582 Loading verify state
3583 ~~~~~~~~~~~~~~~~~~~~
3585 To load stored write state, a read verification job file must contain the
3586 :option:`verify_state_load` option. If that is set, fio will load the previously
3587 stored state. For a local fio run this is done by loading the files directly,
3588 and on a client/server run, the server backend will ask the client to send the
3589 files over and load them from there.
3595 Fio supports a variety of log file formats, for logging latencies, bandwidth,
3596 and IOPS. The logs share a common format, which looks like this:
3598 *time* (`msec`), *value*, *data direction*, *block size* (`bytes`),
3601 *Time* for the log entry is always in milliseconds. The *value* logged depends
3602 on the type of log, it will be one of the following:
3605 Value is latency in nsecs
3611 *Data direction* is one of the following:
3620 The entry's *block size* is always in bytes. The *offset* is the offset, in bytes,
3621 from the start of the file, for that particular I/O. The logging of the offset can be
3622 toggled with :option:`log_offset`.
3624 Fio defaults to logging every individual I/O. When IOPS are logged for individual
3625 I/Os the *value* entry will always be 1. If windowed logging is enabled through
3626 :option:`log_avg_msec`, fio logs the average values over the specified period of time.
3627 If windowed logging is enabled and :option:`log_max_value` is set, then fio logs
3628 maximum values in that window instead of averages. Since *data direction*, *block
3629 size* and *offset* are per-I/O values, if windowed logging is enabled they
3630 aren't applicable and will be 0.
3635 Normally fio is invoked as a stand-alone application on the machine where the
3636 I/O workload should be generated. However, the backend and frontend of fio can
3637 be run separately i.e., the fio server can generate an I/O workload on the "Device
3638 Under Test" while being controlled by a client on another machine.
3640 Start the server on the machine which has access to the storage DUT::
3644 where `args` defines what fio listens to. The arguments are of the form
3645 ``type,hostname`` or ``IP,port``. *type* is either ``ip`` (or ip4) for TCP/IP
3646 v4, ``ip6`` for TCP/IP v6, or ``sock`` for a local unix domain socket.
3647 *hostname* is either a hostname or IP address, and *port* is the port to listen
3648 to (only valid for TCP/IP, not a local socket). Some examples:
3652 Start a fio server, listening on all interfaces on the default port (8765).
3654 2) ``fio --server=ip:hostname,4444``
3656 Start a fio server, listening on IP belonging to hostname and on port 4444.
3658 3) ``fio --server=ip6:::1,4444``
3660 Start a fio server, listening on IPv6 localhost ::1 and on port 4444.
3662 4) ``fio --server=,4444``
3664 Start a fio server, listening on all interfaces on port 4444.
3666 5) ``fio --server=1.2.3.4``
3668 Start a fio server, listening on IP 1.2.3.4 on the default port.
3670 6) ``fio --server=sock:/tmp/fio.sock``
3672 Start a fio server, listening on the local socket :file:`/tmp/fio.sock`.
3674 Once a server is running, a "client" can connect to the fio server with::
3676 fio <local-args> --client=<server> <remote-args> <job file(s)>
3678 where `local-args` are arguments for the client where it is running, `server`
3679 is the connect string, and `remote-args` and `job file(s)` are sent to the
3680 server. The `server` string follows the same format as it does on the server
3681 side, to allow IP/hostname/socket and port strings.
3683 Fio can connect to multiple servers this way::
3685 fio --client=<server1> <job file(s)> --client=<server2> <job file(s)>
3687 If the job file is located on the fio server, then you can tell the server to
3688 load a local file as well. This is done by using :option:`--remote-config` ::
3690 fio --client=server --remote-config /path/to/file.fio
3692 Then fio will open this local (to the server) job file instead of being passed
3693 one from the client.
3695 If you have many servers (example: 100 VMs/containers), you can input a pathname
3696 of a file containing host IPs/names as the parameter value for the
3697 :option:`--client` option. For example, here is an example :file:`host.list`
3698 file containing 2 hostnames::
3700 host1.your.dns.domain
3701 host2.your.dns.domain
3703 The fio command would then be::
3705 fio --client=host.list <job file(s)>
3707 In this mode, you cannot input server-specific parameters or job files -- all
3708 servers receive the same job file.
3710 In order to let ``fio --client`` runs use a shared filesystem from multiple
3711 hosts, ``fio --client`` now prepends the IP address of the server to the
3712 filename. For example, if fio is using the directory :file:`/mnt/nfs/fio` and is
3713 writing filename :file:`fileio.tmp`, with a :option:`--client` `hostfile`
3714 containing two hostnames ``h1`` and ``h2`` with IP addresses 192.168.10.120 and
3715 192.168.10.121, then fio will create two files::
3717 /mnt/nfs/fio/192.168.10.120.fileio.tmp
3718 /mnt/nfs/fio/192.168.10.121.fileio.tmp