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 Dump info related to steadystate detection.
99 Dump info related to the helper thread.
101 Dump info related to support for zoned block devices.
103 Show available debug options.
105 .. option:: --parse-only
107 Parse options only, don't start any I/O.
109 .. option:: --merge-blktrace-only
111 Merge blktraces only, don't start any I/O.
113 .. option:: --output=filename
115 Write output to file `filename`.
117 .. option:: --output-format=format
119 Set the reporting `format` to `normal`, `terse`, `json`, or `json+`. Multiple
120 formats can be selected, separated by a comma. `terse` is a CSV based
121 format. `json+` is like `json`, except it adds a full dump of the latency
124 .. option:: --bandwidth-log
126 Generate aggregate bandwidth logs.
128 .. option:: --minimal
130 Print statistics in a terse, semicolon-delimited format.
132 .. option:: --append-terse
134 Print statistics in selected mode AND terse, semicolon-delimited format.
135 **Deprecated**, use :option:`--output-format` instead to select multiple
138 .. option:: --terse-version=version
140 Set terse `version` output format (default 3, or 2 or 4 or 5).
142 .. option:: --version
144 Print version information and exit.
148 Print a summary of the command line options and exit.
150 .. option:: --cpuclock-test
152 Perform test and validation of internal CPU clock.
154 .. option:: --crctest=[test]
156 Test the speed of the built-in checksumming functions. If no argument is
157 given, all of them are tested. Alternatively, a comma separated list can
158 be passed, in which case the given ones are tested.
160 .. option:: --cmdhelp=command
162 Print help information for `command`. May be ``all`` for all commands.
164 .. option:: --enghelp=[ioengine[,command]]
166 List all commands defined by `ioengine`, or print help for `command`
167 defined by `ioengine`. If no `ioengine` is given, list all
170 .. option:: --showcmd
172 Convert given job files to a set of command-line options.
174 .. option:: --readonly
176 Turn on safety read-only checks, preventing writes and trims. The
177 ``--readonly`` option is an extra safety guard to prevent users from
178 accidentally starting a write or trim workload when that is not desired.
179 Fio will only modify the device under test if
180 `rw=write/randwrite/rw/randrw/trim/randtrim/trimwrite` is given. This
181 safety net can be used as an extra precaution.
183 .. option:: --eta=when
185 Specifies when real-time ETA estimate should be printed. `when` may be
186 `always`, `never` or `auto`. `auto` is the default, it prints ETA
187 when requested if the output is a TTY. `always` disregards the output
188 type, and prints ETA when requested. `never` never prints ETA.
190 .. option:: --eta-interval=time
192 By default, fio requests client ETA status roughly every second. With
193 this option, the interval is configurable. Fio imposes a minimum
194 allowed time to avoid flooding the console, less than 250 msec is
197 .. option:: --eta-newline=time
199 Force a new line for every `time` period passed. When the unit is omitted,
200 the value is interpreted in seconds.
202 .. option:: --status-interval=time
204 Force a full status dump of cumulative (from job start) values at `time`
205 intervals. This option does *not* provide per-period measurements. So
206 values such as bandwidth are running averages. When the time unit is omitted,
207 `time` is interpreted in seconds. Note that using this option with
208 ``--output-format=json`` will yield output that technically isn't valid
209 json, since the output will be collated sets of valid json. It will need
210 to be split into valid sets of json after the run.
212 .. option:: --section=name
214 Only run specified section `name` in job file. Multiple sections can be specified.
215 The ``--section`` option allows one to combine related jobs into one file.
216 E.g. one job file could define light, moderate, and heavy sections. Tell
217 fio to run only the "heavy" section by giving ``--section=heavy``
218 command line option. One can also specify the "write" operations in one
219 section and "verify" operation in another section. The ``--section`` option
220 only applies to job sections. The reserved *global* section is always
223 .. option:: --alloc-size=kb
225 Allocate additional internal smalloc pools of size `kb` in KiB. The
226 ``--alloc-size`` option increases shared memory set aside for use by fio.
227 If running large jobs with randommap enabled, fio can run out of memory.
228 Smalloc is an internal allocator for shared structures from a fixed size
229 memory pool and can grow to 16 pools. The pool size defaults to 16MiB.
231 NOTE: While running :file:`.fio_smalloc.*` backing store files are visible
234 .. option:: --warnings-fatal
236 All fio parser warnings are fatal, causing fio to exit with an
239 .. option:: --max-jobs=nr
241 Set the maximum number of threads/processes to support to `nr`.
242 NOTE: On Linux, it may be necessary to increase the shared-memory
243 limit (:file:`/proc/sys/kernel/shmmax`) if fio runs into errors while
246 .. option:: --server=args
248 Start a backend server, with `args` specifying what to listen to.
249 See `Client/Server`_ section.
251 .. option:: --daemonize=pidfile
253 Background a fio server, writing the pid to the given `pidfile` file.
255 .. option:: --client=hostname
257 Instead of running the jobs locally, send and run them on the given `hostname`
258 or set of `hostname`\s. See `Client/Server`_ section.
260 .. option:: --remote-config=file
262 Tell fio server to load this local `file`.
264 .. option:: --idle-prof=option
266 Report CPU idleness. `option` is one of the following:
269 Run unit work calibration only and exit.
272 Show aggregate system idleness and unit work.
275 As **system** but also show per CPU idleness.
277 .. option:: --inflate-log=log
279 Inflate and output compressed `log`.
281 .. option:: --trigger-file=file
283 Execute trigger command when `file` exists.
285 .. option:: --trigger-timeout=time
287 Execute trigger at this `time`.
289 .. option:: --trigger=command
291 Set this `command` as local trigger.
293 .. option:: --trigger-remote=command
295 Set this `command` as remote trigger.
297 .. option:: --aux-path=path
299 Use the directory specified by `path` for generated state files instead
300 of the current working directory.
302 Any parameters following the options will be assumed to be job files, unless
303 they match a job file parameter. Multiple job files can be listed and each job
304 file will be regarded as a separate group. Fio will :option:`stonewall`
305 execution between each group.
311 As previously described, fio accepts one or more job files describing what it is
312 supposed to do. The job file format is the classic ini file, where the names
313 enclosed in [] brackets define the job name. You are free to use any ASCII name
314 you want, except *global* which has special meaning. Following the job name is
315 a sequence of zero or more parameters, one per line, that define the behavior of
316 the job. If the first character in a line is a ';' or a '#', the entire line is
317 discarded as a comment.
319 A *global* section sets defaults for the jobs described in that file. A job may
320 override a *global* section parameter, and a job file may even have several
321 *global* sections if so desired. A job is only affected by a *global* section
324 The :option:`--cmdhelp` option also lists all options. If used with a `command`
325 argument, :option:`--cmdhelp` will detail the given `command`.
327 See the `examples/` directory for inspiration on how to write job files. Note
328 the copyright and license requirements currently apply to `examples/` files.
330 So let's look at a really simple job file that defines two processes, each
331 randomly reading from a 128MiB file:
335 ; -- start job file --
346 As you can see, the job file sections themselves are empty as all the described
347 parameters are shared. As no :option:`filename` option is given, fio makes up a
348 `filename` for each of the jobs as it sees fit. On the command line, this job
349 would look as follows::
351 $ fio --name=global --rw=randread --size=128m --name=job1 --name=job2
354 Let's look at an example that has a number of processes writing randomly to
359 ; -- start job file --
370 Here we have no *global* section, as we only have one job defined anyway. We
371 want to use async I/O here, with a depth of 4 for each file. We also increased
372 the buffer size used to 32KiB and define numjobs to 4 to fork 4 identical
373 jobs. The result is 4 processes each randomly writing to their own 64MiB
374 file. Instead of using the above job file, you could have given the parameters
375 on the command line. For this case, you would specify::
377 $ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4
379 When fio is utilized as a basis of any reasonably large test suite, it might be
380 desirable to share a set of standardized settings across multiple job files.
381 Instead of copy/pasting such settings, any section may pull in an external
382 :file:`filename.fio` file with *include filename* directive, as in the following
385 ; -- start job file including.fio --
389 include glob-include.fio
396 include test-include.fio
397 ; -- end job file including.fio --
401 ; -- start job file glob-include.fio --
404 ; -- end job file glob-include.fio --
408 ; -- start job file test-include.fio --
411 ; -- end job file test-include.fio --
413 Settings pulled into a section apply to that section only (except *global*
414 section). Include directives may be nested in that any included file may contain
415 further include directive(s). Include files may not contain [] sections.
418 Environment variables
419 ~~~~~~~~~~~~~~~~~~~~~
421 Fio also supports environment variable expansion in job files. Any sub-string of
422 the form ``${VARNAME}`` as part of an option value (in other words, on the right
423 of the '='), will be expanded to the value of the environment variable called
424 `VARNAME`. If no such environment variable is defined, or `VARNAME` is the
425 empty string, the empty string will be substituted.
427 As an example, let's look at a sample fio invocation and job file::
429 $ SIZE=64m NUMJOBS=4 fio jobfile.fio
433 ; -- start job file --
440 This will expand to the following equivalent job file at runtime:
444 ; -- start job file --
451 Fio ships with a few example job files, you can also look there for inspiration.
456 Additionally, fio has a set of reserved keywords that will be replaced
457 internally with the appropriate value. Those keywords are:
461 The architecture page size of the running system.
465 Megabytes of total memory in the system.
469 Number of online available CPUs.
471 These can be used on the command line or in the job file, and will be
472 automatically substituted with the current system values when the job is
473 run. Simple math is also supported on these keywords, so you can perform actions
478 and get that properly expanded to 8 times the size of memory in the machine.
484 This section describes in details each parameter associated with a job. Some
485 parameters take an option of a given type, such as an integer or a
486 string. Anywhere a numeric value is required, an arithmetic expression may be
487 used, provided it is surrounded by parentheses. Supported operators are:
496 For time values in expressions, units are microseconds by default. This is
497 different than for time values not in expressions (not enclosed in
498 parentheses). The following types are used:
505 String: A sequence of alphanumeric characters.
508 Integer with possible time suffix. Without a unit value is interpreted as
509 seconds unless otherwise specified. Accepts a suffix of 'd' for days, 'h' for
510 hours, 'm' for minutes, 's' for seconds, 'ms' (or 'msec') for milliseconds and
511 'us' (or 'usec') for microseconds. For example, use 10m for 10 minutes.
516 Integer. A whole number value, which may contain an integer prefix
517 and an integer suffix:
519 [*integer prefix*] **number** [*integer suffix*]
521 The optional *integer prefix* specifies the number's base. The default
522 is decimal. *0x* specifies hexadecimal.
524 The optional *integer suffix* specifies the number's units, and includes an
525 optional unit prefix and an optional unit. For quantities of data, the
526 default unit is bytes. For quantities of time, the default unit is seconds
527 unless otherwise specified.
529 With :option:`kb_base`\=1000, fio follows international standards for unit
530 prefixes. To specify power-of-10 decimal values defined in the
531 International System of Units (SI):
533 * *K* -- means kilo (K) or 1000
534 * *M* -- means mega (M) or 1000**2
535 * *G* -- means giga (G) or 1000**3
536 * *T* -- means tera (T) or 1000**4
537 * *P* -- means peta (P) or 1000**5
539 To specify power-of-2 binary values defined in IEC 80000-13:
541 * *Ki* -- means kibi (Ki) or 1024
542 * *Mi* -- means mebi (Mi) or 1024**2
543 * *Gi* -- means gibi (Gi) or 1024**3
544 * *Ti* -- means tebi (Ti) or 1024**4
545 * *Pi* -- means pebi (Pi) or 1024**5
547 For Zone Block Device Mode:
550 With :option:`kb_base`\=1024 (the default), the unit prefixes are opposite
551 from those specified in the SI and IEC 80000-13 standards to provide
552 compatibility with old scripts. For example, 4k means 4096.
554 For quantities of data, an optional unit of 'B' may be included
555 (e.g., 'kB' is the same as 'k').
557 The *integer suffix* is not case sensitive (e.g., m/mi mean mebi/mega,
558 not milli). 'b' and 'B' both mean byte, not bit.
560 Examples with :option:`kb_base`\=1000:
562 * *4 KiB*: 4096, 4096b, 4096B, 4ki, 4kib, 4kiB, 4Ki, 4KiB
563 * *1 MiB*: 1048576, 1mi, 1024ki
564 * *1 MB*: 1000000, 1m, 1000k
565 * *1 TiB*: 1099511627776, 1ti, 1024gi, 1048576mi
566 * *1 TB*: 1000000000, 1t, 1000m, 1000000k
568 Examples with :option:`kb_base`\=1024 (default):
570 * *4 KiB*: 4096, 4096b, 4096B, 4k, 4kb, 4kB, 4K, 4KB
571 * *1 MiB*: 1048576, 1m, 1024k
572 * *1 MB*: 1000000, 1mi, 1000ki
573 * *1 TiB*: 1099511627776, 1t, 1024g, 1048576m
574 * *1 TB*: 1000000000, 1ti, 1000mi, 1000000ki
576 To specify times (units are not case sensitive):
580 * *M* -- means minutes
581 * *s* -- or sec means seconds (default)
582 * *ms* -- or *msec* means milliseconds
583 * *us* -- or *usec* means microseconds
585 If the option accepts an upper and lower range, use a colon ':' or
586 minus '-' to separate such values. See :ref:`irange <irange>`.
587 If the lower value specified happens to be larger than the upper value
588 the two values are swapped.
593 Boolean. Usually parsed as an integer, however only defined for
594 true and false (1 and 0).
599 Integer range with suffix. Allows value range to be given, such as
600 1024-4096. A colon may also be used as the separator, e.g. 1k:4k. If the
601 option allows two sets of ranges, they can be specified with a ',' or '/'
602 delimiter: 1k-4k/8k-32k. Also see :ref:`int <int>`.
605 A list of floating point numbers, separated by a ':' character.
607 With the above in mind, here follows the complete list of fio job parameters.
613 .. option:: kb_base=int
615 Select the interpretation of unit prefixes in input parameters.
618 Inputs comply with IEC 80000-13 and the International
619 System of Units (SI). Use:
621 - power-of-2 values with IEC prefixes (e.g., KiB)
622 - power-of-10 values with SI prefixes (e.g., kB)
625 Compatibility mode (default). To avoid breaking old scripts:
627 - power-of-2 values with SI prefixes
628 - power-of-10 values with IEC prefixes
630 See :option:`bs` for more details on input parameters.
632 Outputs always use correct prefixes. Most outputs include both
635 bw=2383.3kB/s (2327.4KiB/s)
637 If only one value is reported, then kb_base selects the one to use:
639 **1000** -- SI prefixes
641 **1024** -- IEC prefixes
643 .. option:: unit_base=int
645 Base unit for reporting. Allowed values are:
648 Use auto-detection (default).
660 ASCII name of the job. This may be used to override the name printed by fio
661 for this job. Otherwise the job name is used. On the command line this
662 parameter has the special purpose of also signaling the start of a new job.
664 .. option:: description=str
666 Text description of the job. Doesn't do anything except dump this text
667 description when this job is run. It's not parsed.
669 .. option:: loops=int
671 Run the specified number of iterations of this job. Used to repeat the same
672 workload a given number of times. Defaults to 1.
674 .. option:: numjobs=int
676 Create the specified number of clones of this job. Each clone of job
677 is spawned as an independent thread or process. May be used to setup a
678 larger number of threads/processes doing the same thing. Each thread is
679 reported separately; to see statistics for all clones as a whole, use
680 :option:`group_reporting` in conjunction with :option:`new_group`.
681 See :option:`--max-jobs`. Default: 1.
684 Time related parameters
685 ~~~~~~~~~~~~~~~~~~~~~~~
687 .. option:: runtime=time
689 Tell fio to terminate processing after the specified period of time. It
690 can be quite hard to determine for how long a specified job will run, so
691 this parameter is handy to cap the total runtime to a given time. When
692 the unit is omitted, the value is interpreted in seconds.
694 .. option:: time_based
696 If set, fio will run for the duration of the :option:`runtime` specified
697 even if the file(s) are completely read or written. It will simply loop over
698 the same workload as many times as the :option:`runtime` allows.
700 .. option:: startdelay=irange(time)
702 Delay the start of job for the specified amount of time. Can be a single
703 value or a range. When given as a range, each thread will choose a value
704 randomly from within the range. Value is in seconds if a unit is omitted.
706 .. option:: ramp_time=time
708 If set, fio will run the specified workload for this amount of time before
709 logging any performance numbers. Useful for letting performance settle
710 before logging results, thus minimizing the runtime required for stable
711 results. Note that the ``ramp_time`` is considered lead in time for a job,
712 thus it will increase the total runtime if a special timeout or
713 :option:`runtime` is specified. When the unit is omitted, the value is
716 .. option:: clocksource=str
718 Use the given clocksource as the base of timing. The supported options are:
721 :manpage:`gettimeofday(2)`
724 :manpage:`clock_gettime(2)`
727 Internal CPU clock source
729 cpu is the preferred clocksource if it is reliable, as it is very fast (and
730 fio is heavy on time calls). Fio will automatically use this clocksource if
731 it's supported and considered reliable on the system it is running on,
732 unless another clocksource is specifically set. For x86/x86-64 CPUs, this
733 means supporting TSC Invariant.
735 .. option:: gtod_reduce=bool
737 Enable all of the :manpage:`gettimeofday(2)` reducing options
738 (:option:`disable_clat`, :option:`disable_slat`, :option:`disable_bw_measurement`) plus
739 reduce precision of the timeout somewhat to really shrink the
740 :manpage:`gettimeofday(2)` call count. With this option enabled, we only do
741 about 0.4% of the :manpage:`gettimeofday(2)` calls we would have done if all
742 time keeping was enabled.
744 .. option:: gtod_cpu=int
746 Sometimes it's cheaper to dedicate a single thread of execution to just
747 getting the current time. Fio (and databases, for instance) are very
748 intensive on :manpage:`gettimeofday(2)` calls. With this option, you can set
749 one CPU aside for doing nothing but logging current time to a shared memory
750 location. Then the other threads/processes that run I/O workloads need only
751 copy that segment, instead of entering the kernel with a
752 :manpage:`gettimeofday(2)` call. The CPU set aside for doing these time
753 calls will be excluded from other uses. Fio will manually clear it from the
754 CPU mask of other jobs.
760 .. option:: directory=str
762 Prefix filenames with this directory. Used to place files in a different
763 location than :file:`./`. You can specify a number of directories by
764 separating the names with a ':' character. These directories will be
765 assigned equally distributed to job clones created by :option:`numjobs` as
766 long as they are using generated filenames. If specific `filename(s)` are
767 set fio will use the first listed directory, and thereby matching the
768 `filename` semantic (which generates a file for each clone if not
769 specified, but lets all clones use the same file if set).
771 See the :option:`filename` option for information on how to escape "``:``"
772 characters within the directory path itself.
774 Note: To control the directory fio will use for internal state files
775 use :option:`--aux-path`.
777 .. option:: filename=str
779 Fio normally makes up a `filename` based on the job name, thread number, and
780 file number (see :option:`filename_format`). If you want to share files
781 between threads in a job or several
782 jobs with fixed file paths, specify a `filename` for each of them to override
783 the default. If the ioengine is file based, you can specify a number of files
784 by separating the names with a ':' colon. So if you wanted a job to open
785 :file:`/dev/sda` and :file:`/dev/sdb` as the two working files, you would use
786 ``filename=/dev/sda:/dev/sdb``. This also means that whenever this option is
787 specified, :option:`nrfiles` is ignored. The size of regular files specified
788 by this option will be :option:`size` divided by number of files unless an
789 explicit size is specified by :option:`filesize`.
791 Each colon in the wanted path must be escaped with a ``\``
792 character. For instance, if the path is :file:`/dev/dsk/foo@3,0:c` then you
793 would use ``filename=/dev/dsk/foo@3,0\:c`` and if the path is
794 :file:`F:\\filename` then you would use ``filename=F\:\filename``.
796 On Windows, disk devices are accessed as :file:`\\\\.\\PhysicalDrive0` for
797 the first device, :file:`\\\\.\\PhysicalDrive1` for the second etc.
798 Note: Windows and FreeBSD prevent write access to areas
799 of the disk containing in-use data (e.g. filesystems).
801 The filename "`-`" is a reserved name, meaning *stdin* or *stdout*. Which
802 of the two depends on the read/write direction set.
804 .. option:: filename_format=str
806 If sharing multiple files between jobs, it is usually necessary to have fio
807 generate the exact names that you want. By default, fio will name a file
808 based on the default file format specification of
809 :file:`jobname.jobnumber.filenumber`. With this option, that can be
810 customized. Fio will recognize and replace the following keywords in this
814 The name of the worker thread or process.
816 IP of the fio process when using client/server mode.
818 The incremental number of the worker thread or process.
820 The incremental number of the file for that worker thread or
823 To have dependent jobs share a set of files, this option can be set to have
824 fio generate filenames that are shared between the two. For instance, if
825 :file:`testfiles.$filenum` is specified, file number 4 for any job will be
826 named :file:`testfiles.4`. The default of :file:`$jobname.$jobnum.$filenum`
827 will be used if no other format specifier is given.
829 If you specify a path then the directories will be created up to the
830 main directory for the file. So for example if you specify
831 ``filename_format=a/b/c/$jobnum`` then the directories a/b/c will be
832 created before the file setup part of the job. If you specify
833 :option:`directory` then the path will be relative that directory,
834 otherwise it is treated as the absolute path.
836 .. option:: unique_filename=bool
838 To avoid collisions between networked clients, fio defaults to prefixing any
839 generated filenames (with a directory specified) with the source of the
840 client connecting. To disable this behavior, set this option to 0.
842 .. option:: opendir=str
844 Recursively open any files below directory `str`.
846 .. option:: lockfile=str
848 Fio defaults to not locking any files before it does I/O to them. If a file
849 or file descriptor is shared, fio can serialize I/O to that file to make the
850 end result consistent. This is usual for emulating real workloads that share
851 files. The lock modes are:
854 No locking. The default.
856 Only one thread or process may do I/O at a time, excluding all
859 Read-write locking on the file. Many readers may
860 access the file at the same time, but writes get exclusive access.
862 .. option:: nrfiles=int
864 Number of files to use for this job. Defaults to 1. The size of files
865 will be :option:`size` divided by this unless explicit size is specified by
866 :option:`filesize`. Files are created for each thread separately, and each
867 file will have a file number within its name by default, as explained in
868 :option:`filename` section.
871 .. option:: openfiles=int
873 Number of files to keep open at the same time. Defaults to the same as
874 :option:`nrfiles`, can be set smaller to limit the number simultaneous
877 .. option:: file_service_type=str
879 Defines how fio decides which file from a job to service next. The following
883 Choose a file at random.
886 Round robin over opened files. This is the default.
889 Finish one file before moving on to the next. Multiple files can
890 still be open depending on :option:`openfiles`.
893 Use a *Zipf* distribution to decide what file to access.
896 Use a *Pareto* distribution to decide what file to access.
899 Use a *Gaussian* (normal) distribution to decide what file to
905 For *random*, *roundrobin*, and *sequential*, a postfix can be appended to
906 tell fio how many I/Os to issue before switching to a new file. For example,
907 specifying ``file_service_type=random:8`` would cause fio to issue
908 8 I/Os before selecting a new file at random. For the non-uniform
909 distributions, a floating point postfix can be given to influence how the
910 distribution is skewed. See :option:`random_distribution` for a description
911 of how that would work.
913 .. option:: ioscheduler=str
915 Attempt to switch the device hosting the file to the specified I/O scheduler
918 .. option:: create_serialize=bool
920 If true, serialize the file creation for the jobs. This may be handy to
921 avoid interleaving of data files, which may greatly depend on the filesystem
922 used and even the number of processors in the system. Default: true.
924 .. option:: create_fsync=bool
926 :manpage:`fsync(2)` the data file after creation. This is the default.
928 .. option:: create_on_open=bool
930 If true, don't pre-create files but allow the job's open() to create a file
931 when it's time to do I/O. Default: false -- pre-create all necessary files
934 .. option:: create_only=bool
936 If true, fio will only run the setup phase of the job. If files need to be
937 laid out or updated on disk, only that will be done -- the actual job contents
938 are not executed. Default: false.
940 .. option:: allow_file_create=bool
942 If true, fio is permitted to create files as part of its workload. If this
943 option is false, then fio will error out if
944 the files it needs to use don't already exist. Default: true.
946 .. option:: allow_mounted_write=bool
948 If this isn't set, fio will abort jobs that are destructive (e.g. that write)
949 to what appears to be a mounted device or partition. This should help catch
950 creating inadvertently destructive tests, not realizing that the test will
951 destroy data on the mounted file system. Note that some platforms don't allow
952 writing against a mounted device regardless of this option. Default: false.
954 .. option:: pre_read=bool
956 If this is given, files will be pre-read into memory before starting the
957 given I/O operation. This will also clear the :option:`invalidate` flag,
958 since it is pointless to pre-read and then drop the cache. This will only
959 work for I/O engines that are seek-able, since they allow you to read the
960 same data multiple times. Thus it will not work on non-seekable I/O engines
961 (e.g. network, splice). Default: false.
963 .. option:: unlink=bool
965 Unlink the job files when done. Not the default, as repeated runs of that
966 job would then waste time recreating the file set again and again. Default:
969 .. option:: unlink_each_loop=bool
971 Unlink job files after each iteration or loop. Default: false.
973 .. option:: zonemode=str
978 The :option:`zonerange`, :option:`zonesize`,
979 :option `zonecapacity` and option:`zoneskip`
980 parameters are ignored.
982 I/O happens in a single zone until
983 :option:`zonesize` bytes have been transferred.
984 After that number of bytes has been
985 transferred processing of the next zone
986 starts. :option `zonecapacity` is ignored.
988 Zoned block device mode. I/O happens
989 sequentially in each zone, even if random I/O
990 has been selected. Random I/O happens across
991 all zones instead of being restricted to a
992 single zone. The :option:`zoneskip` parameter
993 is ignored. :option:`zonerange` and
994 :option:`zonesize` must be identical.
995 Trim is handled using a zone reset operation.
996 Trim only considers non-empty sequential write
997 required and sequential write preferred zones.
999 .. option:: zonerange=int
1001 Size of a single zone. See also :option:`zonesize` and
1004 .. option:: zonesize=int
1006 For :option:`zonemode` =strided, this is the number of bytes to
1007 transfer before skipping :option:`zoneskip` bytes. If this parameter
1008 is smaller than :option:`zonerange` then only a fraction of each zone
1009 with :option:`zonerange` bytes will be accessed. If this parameter is
1010 larger than :option:`zonerange` then each zone will be accessed
1011 multiple times before skipping to the next zone.
1013 For :option:`zonemode` =zbd, this is the size of a single zone. The
1014 :option:`zonerange` parameter is ignored in this mode.
1017 .. option:: zonecapacity=int
1019 For :option:`zonemode` =zbd, this defines the capacity of a single zone,
1020 which is the accessible area starting from the zone start address.
1021 This parameter only applies when using :option:`zonemode` =zbd in
1022 combination with regular block devices. If not specified it defaults to
1023 the zone size. If the target device is a zoned block device, the zone
1024 capacity is obtained from the device information and this option is
1027 .. option:: zoneskip=int
1029 For :option:`zonemode` =strided, the number of bytes to skip after
1030 :option:`zonesize` bytes of data have been transferred. This parameter
1031 must be zero for :option:`zonemode` =zbd.
1033 .. option:: read_beyond_wp=bool
1035 This parameter applies to :option:`zonemode` =zbd only.
1037 Zoned block devices are block devices that consist of multiple zones.
1038 Each zone has a type, e.g. conventional or sequential. A conventional
1039 zone can be written at any offset that is a multiple of the block
1040 size. Sequential zones must be written sequentially. The position at
1041 which a write must occur is called the write pointer. A zoned block
1042 device can be either drive managed, host managed or host aware. For
1043 host managed devices the host must ensure that writes happen
1044 sequentially. Fio recognizes host managed devices and serializes
1045 writes to sequential zones for these devices.
1047 If a read occurs in a sequential zone beyond the write pointer then
1048 the zoned block device will complete the read without reading any data
1049 from the storage medium. Since such reads lead to unrealistically high
1050 bandwidth and IOPS numbers fio only reads beyond the write pointer if
1051 explicitly told to do so. Default: false.
1053 .. option:: max_open_zones=int
1055 A zone of a zoned block device is in the open state when it is partially
1056 written (i.e. not all sectors of the zone have been written). Zoned
1057 block devices may have a limit on the total number of zones that can
1058 be simultaneously in the open state, that is, the number of zones that
1059 can be written to simultaneously. The :option:`max_open_zones` parameter
1060 limits the number of zones to which write commands are issued by all fio
1061 jobs, that is, limits the number of zones that will be in the open
1062 state. This parameter is relevant only if the :option:`zonemode` =zbd is
1063 used. The default value is always equal to maximum number of open zones
1064 of the target zoned block device and a value higher than this limit
1065 cannot be specified by users unless the option
1066 :option:`ignore_zone_limits` is specified. When
1067 :option:`ignore_zone_limits` is specified or the target device has no
1068 limit on the number of zones that can be in an open state,
1069 :option:`max_open_zones` can specify 0 to disable any limit on the
1070 number of zones that can be simultaneously written to by all jobs.
1072 .. option:: job_max_open_zones=int
1074 In the same manner as :option:`max_open_zones`, limit the number of open
1075 zones per fio job, that is, the number of zones that a single job can
1076 simultaneously write to. A value of zero indicates no limit.
1079 .. option:: ignore_zone_limits=bool
1081 If this option is used, fio will ignore the maximum number of open
1082 zones limit of the zoned block device in use, thus allowing the
1083 option :option:`max_open_zones` value to be larger than the device
1084 reported limit. Default: false.
1086 .. option:: zone_reset_threshold=float
1088 A number between zero and one that indicates the ratio of written bytes
1089 in the zones with write pointers in the IO range to the size of the IO
1090 range. When current ratio is above this ratio, zones are reset
1091 periodically as :option:`zone_reset_frequency` specifies. If there are
1092 multiple jobs when using this option, the IO range for all write jobs
1095 .. option:: zone_reset_frequency=float
1097 A number between zero and one that indicates how often a zone reset
1098 should be issued if the zone reset threshold has been exceeded. A zone
1099 reset is submitted after each (1 / zone_reset_frequency) write
1100 requests. This and the previous parameter can be used to simulate
1101 garbage collection activity.
1107 .. option:: direct=bool
1109 If value is true, use non-buffered I/O. This is usually O_DIRECT. Note that
1110 OpenBSD and ZFS on Solaris don't support direct I/O. On Windows the synchronous
1111 ioengines don't support direct I/O. Default: false.
1113 .. option:: atomic=bool
1115 If value is true, attempt to use atomic direct I/O. Atomic writes are
1116 guaranteed to be stable once acknowledged by the operating system. Only
1117 Linux supports O_ATOMIC right now.
1119 .. option:: buffered=bool
1121 If value is true, use buffered I/O. This is the opposite of the
1122 :option:`direct` option. Defaults to true.
1124 .. option:: readwrite=str, rw=str
1126 Type of I/O pattern. Accepted values are:
1133 Sequential trims (Linux block devices and SCSI
1134 character devices only).
1140 Random trims (Linux block devices and SCSI
1141 character devices only).
1143 Sequential mixed reads and writes.
1145 Random mixed reads and writes.
1147 Sequential trim+write sequences. Blocks will be trimmed first,
1148 then the same blocks will be written to. So if ``io_size=64K``
1149 is specified, Fio will trim a total of 64K bytes and also
1150 write 64K bytes on the same trimmed blocks. This behaviour
1151 will be consistent with ``number_ios`` or other Fio options
1152 limiting the total bytes or number of I/O's.
1154 Like trimwrite, but uses random offsets rather
1155 than sequential writes.
1157 Fio defaults to read if the option is not specified. For the mixed I/O
1158 types, the default is to split them 50/50. For certain types of I/O the
1159 result may still be skewed a bit, since the speed may be different.
1161 It is possible to specify the number of I/Os to do before getting a new
1162 offset by appending ``:<nr>`` to the end of the string given. For a
1163 random read, it would look like ``rw=randread:8`` for passing in an offset
1164 modifier with a value of 8. If the suffix is used with a sequential I/O
1165 pattern, then the *<nr>* value specified will be **added** to the generated
1166 offset for each I/O turning sequential I/O into sequential I/O with holes.
1167 For instance, using ``rw=write:4k`` will skip 4k for every write. Also see
1168 the :option:`rw_sequencer` option.
1170 .. option:: rw_sequencer=str
1172 If an offset modifier is given by appending a number to the ``rw=<str>``
1173 line, then this option controls how that number modifies the I/O offset
1174 being generated. Accepted values are:
1177 Generate sequential offset.
1179 Generate the same offset.
1181 ``sequential`` is only useful for random I/O, where fio would normally
1182 generate a new random offset for every I/O. If you append e.g. 8 to
1183 randread, i.e. ``rw=randread:8`` you would get a new random offset for
1184 every 8 I/Os. The result would be a sequence of 8 sequential offsets
1185 with a random starting point. However this behavior may change if a
1186 sequential I/O reaches end of the file. As sequential I/O is already
1187 sequential, setting ``sequential`` for that would not result in any
1188 difference. ``identical`` behaves in a similar fashion, except it sends
1189 the same offset 8 number of times before generating a new offset.
1194 rw_sequencer=sequential
1197 The generated sequence of offsets will look like this:
1198 4k, 8k, 12k, 16k, 20k, 24k, 28k, 32k, 92k, 96k, 100k, 104k, 108k,
1199 112k, 116k, 120k, 48k, 52k ...
1204 rw_sequencer=identical
1207 The generated sequence of offsets will look like this:
1208 4k, 4k, 4k, 4k, 4k, 4k, 4k, 4k, 92k, 92k, 92k, 92k, 92k, 92k, 92k, 92k,
1211 .. option:: unified_rw_reporting=str
1213 Fio normally reports statistics on a per data direction basis, meaning that
1214 reads, writes, and trims are accounted and reported separately. This option
1215 determines whether fio reports the results normally, summed together, or as
1217 Accepted values are:
1220 Normal statistics reporting.
1223 Statistics are summed per data direction and reported together.
1226 Statistics are reported normally, followed by the mixed statistics.
1229 Backward-compatible alias for **none**.
1232 Backward-compatible alias for **mixed**.
1237 .. option:: randrepeat=bool
1239 Seed the random number generator used for random I/O patterns in a
1240 predictable way so the pattern is repeatable across runs. Default: true.
1242 .. option:: allrandrepeat=bool
1244 Seed all random number generators in a predictable way so results are
1245 repeatable across runs. Default: false.
1247 .. option:: randseed=int
1249 Seed the random number generators based on this seed value, to be able to
1250 control what sequence of output is being generated. If not set, the random
1251 sequence depends on the :option:`randrepeat` setting.
1253 .. option:: fallocate=str
1255 Whether pre-allocation is performed when laying down files.
1256 Accepted values are:
1259 Do not pre-allocate space.
1262 Use a platform's native pre-allocation call but fall back to
1263 **none** behavior if it fails/is not implemented.
1266 Pre-allocate via :manpage:`posix_fallocate(3)`.
1269 Pre-allocate via :manpage:`fallocate(2)` with
1270 FALLOC_FL_KEEP_SIZE set.
1273 Extend file to final size via :manpage:`ftruncate(2)`
1274 instead of allocating.
1277 Backward-compatible alias for **none**.
1280 Backward-compatible alias for **posix**.
1282 May not be available on all supported platforms. **keep** is only available
1283 on Linux. If using ZFS on Solaris this cannot be set to **posix**
1284 because ZFS doesn't support pre-allocation. Default: **native** if any
1285 pre-allocation methods except **truncate** are available, **none** if not.
1287 Note that using **truncate** on Windows will interact surprisingly
1288 with non-sequential write patterns. When writing to a file that has
1289 been extended by setting the end-of-file information, Windows will
1290 backfill the unwritten portion of the file up to that offset with
1291 zeroes before issuing the new write. This means that a single small
1292 write to the end of an extended file will stall until the entire
1293 file has been filled with zeroes.
1295 .. option:: fadvise_hint=str
1297 Use :manpage:`posix_fadvise(2)` or :manpage:`posix_fadvise(2)` to
1298 advise the kernel on what I/O patterns are likely to be issued.
1299 Accepted values are:
1302 Backwards-compatible hint for "no hint".
1305 Backwards compatible hint for "advise with fio workload type". This
1306 uses **FADV_RANDOM** for a random workload, and **FADV_SEQUENTIAL**
1307 for a sequential workload.
1310 Advise using **FADV_SEQUENTIAL**.
1313 Advise using **FADV_RANDOM**.
1315 .. option:: write_hint=str
1317 Use :manpage:`fcntl(2)` to advise the kernel what life time to expect
1318 from a write. Only supported on Linux, as of version 4.13. Accepted
1322 No particular life time associated with this file.
1325 Data written to this file has a short life time.
1328 Data written to this file has a medium life time.
1331 Data written to this file has a long life time.
1334 Data written to this file has a very long life time.
1336 The values are all relative to each other, and no absolute meaning
1337 should be associated with them.
1339 .. option:: offset=int
1341 Start I/O at the provided offset in the file, given as either a fixed size in
1342 bytes, zones or a percentage. If a percentage is given, the generated offset will be
1343 aligned to the minimum ``blocksize`` or to the value of ``offset_align`` if
1344 provided. Data before the given offset will not be touched. This
1345 effectively caps the file size at `real_size - offset`. Can be combined with
1346 :option:`size` to constrain the start and end range of the I/O workload.
1347 A percentage can be specified by a number between 1 and 100 followed by '%',
1348 for example, ``offset=20%`` to specify 20%. In ZBD mode, value can be set as
1349 number of zones using 'z'.
1351 .. option:: offset_align=int
1353 If set to non-zero value, the byte offset generated by a percentage ``offset``
1354 is aligned upwards to this value. Defaults to 0 meaning that a percentage
1355 offset is aligned to the minimum block size.
1357 .. option:: offset_increment=int
1359 If this is provided, then the real offset becomes `offset + offset_increment
1360 * thread_number`, where the thread number is a counter that starts at 0 and
1361 is incremented for each sub-job (i.e. when :option:`numjobs` option is
1362 specified). This option is useful if there are several jobs which are
1363 intended to operate on a file in parallel disjoint segments, with even
1364 spacing between the starting points. Percentages can be used for this option.
1365 If a percentage is given, the generated offset will be aligned to the minimum
1366 ``blocksize`` or to the value of ``offset_align`` if provided. In ZBD mode, value can
1367 also be set as number of zones using 'z'.
1369 .. option:: number_ios=int
1371 Fio will normally perform I/Os until it has exhausted the size of the region
1372 set by :option:`size`, or if it exhaust the allocated time (or hits an error
1373 condition). With this setting, the range/size can be set independently of
1374 the number of I/Os to perform. When fio reaches this number, it will exit
1375 normally and report status. Note that this does not extend the amount of I/O
1376 that will be done, it will only stop fio if this condition is met before
1377 other end-of-job criteria.
1379 .. option:: fsync=int
1381 If writing to a file, issue an :manpage:`fsync(2)` (or its equivalent) of
1382 the dirty data for every number of blocks given. For example, if you give 32
1383 as a parameter, fio will sync the file after every 32 writes issued. If fio is
1384 using non-buffered I/O, we may not sync the file. The exception is the sg
1385 I/O engine, which synchronizes the disk cache anyway. Defaults to 0, which
1386 means fio does not periodically issue and wait for a sync to complete. Also
1387 see :option:`end_fsync` and :option:`fsync_on_close`.
1389 .. option:: fdatasync=int
1391 Like :option:`fsync` but uses :manpage:`fdatasync(2)` to only sync data and
1392 not metadata blocks. In Windows, DragonFlyBSD or OSX there is no
1393 :manpage:`fdatasync(2)` so this falls back to using :manpage:`fsync(2)`.
1394 Defaults to 0, which means fio does not periodically issue and wait for a
1395 data-only sync to complete.
1397 .. option:: write_barrier=int
1399 Make every `N-th` write a barrier write.
1401 .. option:: sync_file_range=str:int
1403 Use :manpage:`sync_file_range(2)` for every `int` number of write
1404 operations. Fio will track range of writes that have happened since the last
1405 :manpage:`sync_file_range(2)` call. `str` can currently be one or more of:
1408 SYNC_FILE_RANGE_WAIT_BEFORE
1410 SYNC_FILE_RANGE_WRITE
1412 SYNC_FILE_RANGE_WAIT_AFTER
1414 So if you do ``sync_file_range=wait_before,write:8``, fio would use
1415 ``SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE`` for every 8
1416 writes. Also see the :manpage:`sync_file_range(2)` man page. This option is
1419 .. option:: overwrite=bool
1421 If true, writes to a file will always overwrite existing data. If the file
1422 doesn't already exist, it will be created before the write phase begins. If
1423 the file exists and is large enough for the specified write phase, nothing
1424 will be done. Default: false.
1426 .. option:: end_fsync=bool
1428 If true, :manpage:`fsync(2)` file contents when a write stage has completed.
1431 .. option:: fsync_on_close=bool
1433 If true, fio will :manpage:`fsync(2)` a dirty file on close. This differs
1434 from :option:`end_fsync` in that it will happen on every file close, not
1435 just at the end of the job. Default: false.
1437 .. option:: rwmixread=int
1439 Percentage of a mixed workload that should be reads. Default: 50.
1441 .. option:: rwmixwrite=int
1443 Percentage of a mixed workload that should be writes. If both
1444 :option:`rwmixread` and :option:`rwmixwrite` is given and the values do not
1445 add up to 100%, the latter of the two will be used to override the
1446 first. This may interfere with a given rate setting, if fio is asked to
1447 limit reads or writes to a certain rate. If that is the case, then the
1448 distribution may be skewed. Default: 50.
1450 .. option:: random_distribution=str:float[:float][,str:float][,str:float]
1452 By default, fio will use a completely uniform random distribution when asked
1453 to perform random I/O. Sometimes it is useful to skew the distribution in
1454 specific ways, ensuring that some parts of the data is more hot than others.
1455 fio includes the following distribution models:
1458 Uniform random distribution
1467 Normal (Gaussian) distribution
1470 Zoned random distribution
1473 Zone absolute random distribution
1475 When using a **zipf** or **pareto** distribution, an input value is also
1476 needed to define the access pattern. For **zipf**, this is the `Zipf
1477 theta`. For **pareto**, it's the `Pareto power`. Fio includes a test
1478 program, :command:`fio-genzipf`, that can be used visualize what the given input
1479 values will yield in terms of hit rates. If you wanted to use **zipf** with
1480 a `theta` of 1.2, you would use ``random_distribution=zipf:1.2`` as the
1481 option. If a non-uniform model is used, fio will disable use of the random
1482 map. For the **normal** distribution, a normal (Gaussian) deviation is
1483 supplied as a value between 0 and 100.
1485 The second, optional float is allowed for **pareto**, **zipf** and **normal** distributions.
1486 It allows one to set base of distribution in non-default place, giving more control
1487 over most probable outcome. This value is in range [0-1] which maps linearly to
1488 range of possible random values.
1489 Defaults are: random for **pareto** and **zipf**, and 0.5 for **normal**.
1490 If you wanted to use **zipf** with a `theta` of 1.2 centered on 1/4 of allowed value range,
1491 you would use ``random_distribution=zipf:1.2:0.25``.
1493 For a **zoned** distribution, fio supports specifying percentages of I/O
1494 access that should fall within what range of the file or device. For
1495 example, given a criteria of:
1497 * 60% of accesses should be to the first 10%
1498 * 30% of accesses should be to the next 20%
1499 * 8% of accesses should be to the next 30%
1500 * 2% of accesses should be to the next 40%
1502 we can define that through zoning of the random accesses. For the above
1503 example, the user would do::
1505 random_distribution=zoned:60/10:30/20:8/30:2/40
1507 A **zoned_abs** distribution works exactly like the **zoned**, except
1508 that it takes absolute sizes. For example, let's say you wanted to
1509 define access according to the following criteria:
1511 * 60% of accesses should be to the first 20G
1512 * 30% of accesses should be to the next 100G
1513 * 10% of accesses should be to the next 500G
1515 we can define an absolute zoning distribution with:
1517 random_distribution=zoned_abs=60/20G:30/100G:10/500g
1519 For both **zoned** and **zoned_abs**, fio supports defining up to
1522 Similarly to how :option:`bssplit` works for setting ranges and
1523 percentages of block sizes. Like :option:`bssplit`, it's possible to
1524 specify separate zones for reads, writes, and trims. If just one set
1525 is given, it'll apply to all of them. This goes for both **zoned**
1526 **zoned_abs** distributions.
1528 .. option:: percentage_random=int[,int][,int]
1530 For a random workload, set how big a percentage should be random. This
1531 defaults to 100%, in which case the workload is fully random. It can be set
1532 from anywhere from 0 to 100. Setting it to 0 would make the workload fully
1533 sequential. Any setting in between will result in a random mix of sequential
1534 and random I/O, at the given percentages. Comma-separated values may be
1535 specified for reads, writes, and trims as described in :option:`blocksize`.
1537 .. option:: norandommap
1539 Normally fio will cover every block of the file when doing random I/O. If
1540 this option is given, fio will just get a new random offset without looking
1541 at past I/O history. This means that some blocks may not be read or written,
1542 and that some blocks may be read/written more than once. If this option is
1543 used with :option:`verify` and multiple blocksizes (via :option:`bsrange`),
1544 only intact blocks are verified, i.e., partially-overwritten blocks are
1545 ignored. With an async I/O engine and an I/O depth > 1, it is possible for
1546 the same block to be overwritten, which can cause verification errors. Either
1547 do not use norandommap in this case, or also use the lfsr random generator.
1549 .. option:: softrandommap=bool
1551 See :option:`norandommap`. If fio runs with the random block map enabled and
1552 it fails to allocate the map, if this option is set it will continue without
1553 a random block map. As coverage will not be as complete as with random maps,
1554 this option is disabled by default.
1556 .. option:: random_generator=str
1558 Fio supports the following engines for generating I/O offsets for random I/O:
1561 Strong 2^88 cycle random number generator.
1563 Linear feedback shift register generator.
1565 Strong 64-bit 2^258 cycle random number generator.
1567 **tausworthe** is a strong random number generator, but it requires tracking
1568 on the side if we want to ensure that blocks are only read or written
1569 once. **lfsr** guarantees that we never generate the same offset twice, and
1570 it's also less computationally expensive. It's not a true random generator,
1571 however, though for I/O purposes it's typically good enough. **lfsr** only
1572 works with single block sizes, not with workloads that use multiple block
1573 sizes. If used with such a workload, fio may read or write some blocks
1574 multiple times. The default value is **tausworthe**, unless the required
1575 space exceeds 2^32 blocks. If it does, then **tausworthe64** is
1576 selected automatically.
1582 .. option:: blocksize=int[,int][,int], bs=int[,int][,int]
1584 The block size in bytes used for I/O units. Default: 4096. A single value
1585 applies to reads, writes, and trims. Comma-separated values may be
1586 specified for reads, writes, and trims. A value not terminated in a comma
1587 applies to subsequent types.
1592 means 256k for reads, writes and trims.
1595 means 8k for reads, 32k for writes and trims.
1598 means 8k for reads, 32k for writes, and default for trims.
1601 means default for reads, 8k for writes and trims.
1604 means default for reads, 8k for writes, and default for trims.
1606 .. option:: blocksize_range=irange[,irange][,irange], bsrange=irange[,irange][,irange]
1608 A range of block sizes in bytes for I/O units. The issued I/O unit will
1609 always be a multiple of the minimum size, unless
1610 :option:`blocksize_unaligned` is set.
1612 Comma-separated ranges may be specified for reads, writes, and trims as
1613 described in :option:`blocksize`.
1615 Example: ``bsrange=1k-4k,2k-8k``.
1617 .. option:: bssplit=str[,str][,str]
1619 Sometimes you want even finer grained control of the block sizes
1620 issued, not just an even split between them. This option allows you to
1621 weight various block sizes, so that you are able to define a specific
1622 amount of block sizes issued. The format for this option is::
1624 bssplit=blocksize/percentage:blocksize/percentage
1626 for as many block sizes as needed. So if you want to define a workload
1627 that has 50% 64k blocks, 10% 4k blocks, and 40% 32k blocks, you would
1630 bssplit=4k/10:64k/50:32k/40
1632 Ordering does not matter. If the percentage is left blank, fio will
1633 fill in the remaining values evenly. So a bssplit option like this one::
1635 bssplit=4k/50:1k/:32k/
1637 would have 50% 4k ios, and 25% 1k and 32k ios. The percentages always
1638 add up to 100, if bssplit is given a range that adds up to more, it
1641 Comma-separated values may be specified for reads, writes, and trims as
1642 described in :option:`blocksize`.
1644 If you want a workload that has 50% 2k reads and 50% 4k reads, while
1645 having 90% 4k writes and 10% 8k writes, you would specify::
1647 bssplit=2k/50:4k/50,4k/90:8k/10
1649 Fio supports defining up to 64 different weights for each data
1652 .. option:: blocksize_unaligned, bs_unaligned
1654 If set, fio will issue I/O units with any size within
1655 :option:`blocksize_range`, not just multiples of the minimum size. This
1656 typically won't work with direct I/O, as that normally requires sector
1659 .. option:: bs_is_seq_rand=bool
1661 If this option is set, fio will use the normal read,write blocksize settings
1662 as sequential,random blocksize settings instead. Any random read or write
1663 will use the WRITE blocksize settings, and any sequential read or write will
1664 use the READ blocksize settings.
1666 .. option:: blockalign=int[,int][,int], ba=int[,int][,int]
1668 Boundary to which fio will align random I/O units. Default:
1669 :option:`blocksize`. Minimum alignment is typically 512b for using direct
1670 I/O, though it usually depends on the hardware block size. This option is
1671 mutually exclusive with using a random map for files, so it will turn off
1672 that option. Comma-separated values may be specified for reads, writes, and
1673 trims as described in :option:`blocksize`.
1679 .. option:: zero_buffers
1681 Initialize buffers with all zeros. Default: fill buffers with random data.
1683 .. option:: refill_buffers
1685 If this option is given, fio will refill the I/O buffers on every
1686 submit. Only makes sense if :option:`zero_buffers` isn't specified,
1687 naturally. Defaults to being unset i.e., the buffer is only filled at
1688 init time and the data in it is reused when possible but if any of
1689 :option:`verify`, :option:`buffer_compress_percentage` or
1690 :option:`dedupe_percentage` are enabled then `refill_buffers` is also
1691 automatically enabled.
1693 .. option:: scramble_buffers=bool
1695 If :option:`refill_buffers` is too costly and the target is using data
1696 deduplication, then setting this option will slightly modify the I/O buffer
1697 contents to defeat normal de-dupe attempts. This is not enough to defeat
1698 more clever block compression attempts, but it will stop naive dedupe of
1699 blocks. Default: true.
1701 .. option:: buffer_compress_percentage=int
1703 If this is set, then fio will attempt to provide I/O buffer content
1704 (on WRITEs) that compresses to the specified level. Fio does this by
1705 providing a mix of random data followed by fixed pattern data. The
1706 fixed pattern is either zeros, or the pattern specified by
1707 :option:`buffer_pattern`. If the `buffer_pattern` option is used, it
1708 might skew the compression ratio slightly. Setting
1709 `buffer_compress_percentage` to a value other than 100 will also
1710 enable :option:`refill_buffers` in order to reduce the likelihood that
1711 adjacent blocks are so similar that they over compress when seen
1712 together. See :option:`buffer_compress_chunk` for how to set a finer or
1713 coarser granularity for the random/fixed data region. Defaults to unset
1714 i.e., buffer data will not adhere to any compression level.
1716 .. option:: buffer_compress_chunk=int
1718 This setting allows fio to manage how big the random/fixed data region
1719 is when using :option:`buffer_compress_percentage`. When
1720 `buffer_compress_chunk` is set to some non-zero value smaller than the
1721 block size, fio can repeat the random/fixed region throughout the I/O
1722 buffer at the specified interval (which particularly useful when
1723 bigger block sizes are used for a job). When set to 0, fio will use a
1724 chunk size that matches the block size resulting in a single
1725 random/fixed region within the I/O buffer. Defaults to 512. When the
1726 unit is omitted, the value is interpreted in bytes.
1728 .. option:: buffer_pattern=str
1730 If set, fio will fill the I/O buffers with this pattern or with the contents
1731 of a file. If not set, the contents of I/O buffers are defined by the other
1732 options related to buffer contents. The setting can be any pattern of bytes,
1733 and can be prefixed with 0x for hex values. It may also be a string, where
1734 the string must then be wrapped with ``""``. Or it may also be a filename,
1735 where the filename must be wrapped with ``''`` in which case the file is
1736 opened and read. Note that not all the file contents will be read if that
1737 would cause the buffers to overflow. So, for example::
1739 buffer_pattern='filename'
1743 buffer_pattern="abcd"
1751 buffer_pattern=0xdeadface
1753 Also you can combine everything together in any order::
1755 buffer_pattern=0xdeadface"abcd"-12'filename'
1757 .. option:: dedupe_percentage=int
1759 If set, fio will generate this percentage of identical buffers when
1760 writing. These buffers will be naturally dedupable. The contents of the
1761 buffers depend on what other buffer compression settings have been set. It's
1762 possible to have the individual buffers either fully compressible, or not at
1763 all -- this option only controls the distribution of unique buffers. Setting
1764 this option will also enable :option:`refill_buffers` to prevent every buffer
1767 .. option:: dedupe_mode=str
1769 If ``dedupe_percentage=<int>`` is given, then this option controls how fio
1770 generates the dedupe buffers.
1773 Generate dedupe buffers by repeating previous writes
1775 Generate dedupe buffers from working set
1777 ``repeat`` is the default option for fio. Dedupe buffers are generated
1778 by repeating previous unique write.
1780 ``working_set`` is a more realistic workload.
1781 With ``working_set``, ``dedupe_working_set_percentage=<int>`` should be provided.
1782 Given that, fio will use the initial unique write buffers as its working set.
1783 Upon deciding to dedupe, fio will randomly choose a buffer from the working set.
1784 Note that by using ``working_set`` the dedupe percentage will converge
1785 to the desired over time while ``repeat`` maintains the desired percentage
1788 .. option:: dedupe_working_set_percentage=int
1790 If ``dedupe_mode=<str>`` is set to ``working_set``, then this controls
1791 the percentage of size of the file or device used as the buffers
1792 fio will choose to generate the dedupe buffers from
1794 Note that size needs to be explicitly provided and only 1 file per
1797 .. option:: dedupe_global=bool
1799 This controls whether the deduplication buffers will be shared amongst
1800 all jobs that have this option set. The buffers are spread evenly between
1803 .. option:: invalidate=bool
1805 Invalidate the buffer/page cache parts of the files to be used prior to
1806 starting I/O if the platform and file type support it. Defaults to true.
1807 This will be ignored if :option:`pre_read` is also specified for the
1810 .. option:: sync=str
1812 Whether, and what type, of synchronous I/O to use for writes. The allowed
1816 Do not use synchronous IO, the default.
1822 Use synchronous file IO. For the majority of I/O engines,
1823 this means using O_SYNC.
1829 Use synchronous data IO. For the majority of I/O engines,
1830 this means using O_DSYNC.
1833 .. option:: iomem=str, mem=str
1835 Fio can use various types of memory as the I/O unit buffer. The allowed
1839 Use memory from :manpage:`malloc(3)` as the buffers. Default memory
1843 Use shared memory as the buffers. Allocated through
1844 :manpage:`shmget(2)`.
1847 Same as shm, but use huge pages as backing.
1850 Use :manpage:`mmap(2)` to allocate buffers. May either be anonymous memory, or can
1851 be file backed if a filename is given after the option. The format
1852 is `mem=mmap:/path/to/file`.
1855 Use a memory mapped huge file as the buffer backing. Append filename
1856 after mmaphuge, ala `mem=mmaphuge:/hugetlbfs/file`.
1859 Same as mmap, but use a MMAP_SHARED mapping.
1862 Use GPU memory as the buffers for GPUDirect RDMA benchmark.
1863 The :option:`ioengine` must be `rdma`.
1865 The area allocated is a function of the maximum allowed bs size for the job,
1866 multiplied by the I/O depth given. Note that for **shmhuge** and
1867 **mmaphuge** to work, the system must have free huge pages allocated. This
1868 can normally be checked and set by reading/writing
1869 :file:`/proc/sys/vm/nr_hugepages` on a Linux system. Fio assumes a huge page
1870 is 2 or 4MiB in size depending on the platform. So to calculate the
1871 number of huge pages you need for a given job file, add up the I/O
1872 depth of all jobs (normally one unless :option:`iodepth` is used) and
1873 multiply by the maximum bs set. Then divide that number by the huge
1874 page size. You can see the size of the huge pages in
1875 :file:`/proc/meminfo`. If no huge pages are allocated by having a
1876 non-zero number in `nr_hugepages`, using **mmaphuge** or **shmhuge**
1877 will fail. Also see :option:`hugepage-size`.
1879 **mmaphuge** also needs to have hugetlbfs mounted and the file location
1880 should point there. So if it's mounted in :file:`/huge`, you would use
1881 `mem=mmaphuge:/huge/somefile`.
1883 .. option:: iomem_align=int, mem_align=int
1885 This indicates the memory alignment of the I/O memory buffers. Note that
1886 the given alignment is applied to the first I/O unit buffer, if using
1887 :option:`iodepth` the alignment of the following buffers are given by the
1888 :option:`bs` used. In other words, if using a :option:`bs` that is a
1889 multiple of the page sized in the system, all buffers will be aligned to
1890 this value. If using a :option:`bs` that is not page aligned, the alignment
1891 of subsequent I/O memory buffers is the sum of the :option:`iomem_align` and
1894 .. option:: hugepage-size=int
1896 Defines the size of a huge page. Must at least be equal to the system
1897 setting, see :file:`/proc/meminfo` and
1898 :file:`/sys/kernel/mm/hugepages/`. Defaults to 2 or 4MiB depending on
1899 the platform. Should probably always be a multiple of megabytes, so
1900 using ``hugepage-size=Xm`` is the preferred way to set this to avoid
1901 setting a non-pow-2 bad value.
1903 .. option:: lockmem=int
1905 Pin the specified amount of memory with :manpage:`mlock(2)`. Can be used to
1906 simulate a smaller amount of memory. The amount specified is per worker.
1912 .. option:: size=int
1914 The total size of file I/O for each thread of this job. Fio will run until
1915 this many bytes has been transferred, unless runtime is altered by other means
1916 such as (1) :option:`runtime`, (2) :option:`io_size` (3) :option:`number_ios`,
1917 (4) gaps/holes while doing I/O's such as ``rw=read:16K``, or (5) sequential
1918 I/O reaching end of the file which is possible when :option:`percentage_random`
1920 Fio will divide this size between the available files determined by options
1921 such as :option:`nrfiles`, :option:`filename`, unless :option:`filesize` is
1922 specified by the job. If the result of division happens to be 0, the size is
1923 set to the physical size of the given files or devices if they exist.
1924 If this option is not specified, fio will use the full size of the given
1925 files or devices. If the files do not exist, size must be given. It is also
1926 possible to give size as a percentage between 1 and 100. If ``size=20%`` is
1927 given, fio will use 20% of the full size of the given files or devices.
1928 In ZBD mode, value can also be set as number of zones using 'z'.
1929 Can be combined with :option:`offset` to constrain the start and end range
1930 that I/O will be done within.
1932 .. option:: io_size=int, io_limit=int
1934 Normally fio operates within the region set by :option:`size`, which means
1935 that the :option:`size` option sets both the region and size of I/O to be
1936 performed. Sometimes that is not what you want. With this option, it is
1937 possible to define just the amount of I/O that fio should do. For instance,
1938 if :option:`size` is set to 20GiB and :option:`io_size` is set to 5GiB, fio
1939 will perform I/O within the first 20GiB but exit when 5GiB have been
1940 done. The opposite is also possible -- if :option:`size` is set to 20GiB,
1941 and :option:`io_size` is set to 40GiB, then fio will do 40GiB of I/O within
1942 the 0..20GiB region.
1944 .. option:: filesize=irange(int)
1946 Individual file sizes. May be a range, in which case fio will select sizes for
1947 files at random within the given range. If not given, each created file is the
1948 same size. This option overrides :option:`size` in terms of file size, i.e. if
1949 :option:`filesize` is specified then :option:`size` becomes merely the default
1950 for :option:`io_size` and has no effect at all if :option:`io_size` is set
1953 .. option:: file_append=bool
1955 Perform I/O after the end of the file. Normally fio will operate within the
1956 size of a file. If this option is set, then fio will append to the file
1957 instead. This has identical behavior to setting :option:`offset` to the size
1958 of a file. This option is ignored on non-regular files.
1960 .. option:: fill_device=bool, fill_fs=bool
1962 Sets size to something really large and waits for ENOSPC (no space left on
1963 device) or EDQUOT (disk quota exceeded)
1964 as the terminating condition. Only makes sense with sequential
1965 write. For a read workload, the mount point will be filled first then I/O
1966 started on the result. This option doesn't make sense if operating on a raw
1967 device node, since the size of that is already known by the file system.
1968 Additionally, writing beyond end-of-device will not return ENOSPC there.
1974 .. option:: ioengine=str
1976 Defines how the job issues I/O to the file. The following types are defined:
1979 Basic :manpage:`read(2)` or :manpage:`write(2)`
1980 I/O. :manpage:`lseek(2)` is used to position the I/O location.
1981 See :option:`fsync` and :option:`fdatasync` for syncing write I/Os.
1984 Basic :manpage:`pread(2)` or :manpage:`pwrite(2)` I/O. Default on
1985 all supported operating systems except for Windows.
1988 Basic :manpage:`readv(2)` or :manpage:`writev(2)` I/O. Will emulate
1989 queuing by coalescing adjacent I/Os into a single submission.
1992 Basic :manpage:`preadv(2)` or :manpage:`pwritev(2)` I/O.
1995 Basic :manpage:`preadv2(2)` or :manpage:`pwritev2(2)` I/O.
1998 Fast Linux native asynchronous I/O. Supports async IO
1999 for both direct and buffered IO.
2000 This engine defines engine specific options.
2003 Fast Linux native asynchronous I/O for pass through commands.
2004 This engine defines engine specific options.
2007 Linux native asynchronous I/O. Note that Linux may only support
2008 queued behavior with non-buffered I/O (set ``direct=1`` or
2010 This engine defines engine specific options.
2013 POSIX asynchronous I/O using :manpage:`aio_read(3)` and
2014 :manpage:`aio_write(3)`.
2017 Solaris native asynchronous I/O.
2020 Windows native asynchronous I/O. Default on Windows.
2023 File is memory mapped with :manpage:`mmap(2)` and data copied
2024 to/from using :manpage:`memcpy(3)`.
2027 :manpage:`splice(2)` is used to transfer the data and
2028 :manpage:`vmsplice(2)` to transfer data from user space to the
2032 SCSI generic sg v3 I/O. May either be synchronous using the SG_IO
2033 ioctl, or if the target is an sg character device we use
2034 :manpage:`read(2)` and :manpage:`write(2)` for asynchronous
2035 I/O. Requires :option:`filename` option to specify either block or
2036 character devices. This engine supports trim operations.
2037 The sg engine includes engine specific options.
2040 Read, write, trim and ZBC/ZAC operations to a zoned
2041 block device using libzbc library. The target can be
2042 either an SG character device or a block device file.
2045 Doesn't transfer any data, just pretends to. This is mainly used to
2046 exercise fio itself and for debugging/testing purposes.
2049 Transfer over the network to given ``host:port``. Depending on the
2050 :option:`protocol` used, the :option:`hostname`, :option:`port`,
2051 :option:`listen` and :option:`filename` options are used to specify
2052 what sort of connection to make, while the :option:`protocol` option
2053 determines which protocol will be used. This engine defines engine
2057 Like **net**, but uses :manpage:`splice(2)` and
2058 :manpage:`vmsplice(2)` to map data and send/receive.
2059 This engine defines engine specific options.
2062 Doesn't transfer any data, but burns CPU cycles according to the
2063 :option:`cpuload`, :option:`cpuchunks` and :option:`cpumode` options.
2064 Setting :option:`cpuload`\=85 will cause that job to do nothing but burn 85%
2065 of the CPU. In case of SMP machines, use :option:`numjobs`\=<nr_of_cpu>
2066 to get desired CPU usage, as the cpuload only loads a
2067 single CPU at the desired rate. A job never finishes unless there is
2068 at least one non-cpuio job.
2069 Setting :option:`cpumode`\=qsort replace the default noop instructions loop
2070 by a qsort algorithm to consume more energy.
2073 The RDMA I/O engine supports both RDMA memory semantics
2074 (RDMA_WRITE/RDMA_READ) and channel semantics (Send/Recv) for the
2075 InfiniBand, RoCE and iWARP protocols. This engine defines engine
2079 I/O engine that does regular fallocate to simulate data transfer as
2083 does fallocate(,mode = FALLOC_FL_KEEP_SIZE,).
2086 does fallocate(,mode = 0).
2089 does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE).
2092 I/O engine that sends :manpage:`ftruncate(2)` operations in response
2093 to write (DDIR_WRITE) events. Each ftruncate issued sets the file's
2094 size to the current block offset. :option:`blocksize` is ignored.
2097 I/O engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate
2098 defragment activity in request to DDIR_WRITE event.
2101 I/O engine supporting direct access to Ceph Reliable Autonomic
2102 Distributed Object Store (RADOS) via librados. This ioengine
2103 defines engine specific options.
2106 I/O engine supporting direct access to Ceph Rados Block Devices
2107 (RBD) via librbd without the need to use the kernel rbd driver. This
2108 ioengine defines engine specific options.
2111 I/O engine supporting GET/PUT requests over HTTP(S) with libcurl to
2112 a WebDAV or S3 endpoint. This ioengine defines engine specific options.
2114 This engine only supports direct IO of iodepth=1; you need to scale this
2115 via numjobs. blocksize defines the size of the objects to be created.
2117 TRIM is translated to object deletion.
2120 Using GlusterFS libgfapi sync interface to direct access to
2121 GlusterFS volumes without having to go through FUSE. This ioengine
2122 defines engine specific options.
2125 Using GlusterFS libgfapi async interface to direct access to
2126 GlusterFS volumes without having to go through FUSE. This ioengine
2127 defines engine specific options.
2130 Read and write through Hadoop (HDFS). The :option:`filename` option
2131 is used to specify host,port of the hdfs name-node to connect. This
2132 engine interprets offsets a little differently. In HDFS, files once
2133 created cannot be modified so random writes are not possible. To
2134 imitate this the libhdfs engine expects a bunch of small files to be
2135 created over HDFS and will randomly pick a file from them
2136 based on the offset generated by fio backend (see the example
2137 job file to create such files, use ``rw=write`` option). Please
2138 note, it may be necessary to set environment variables to work
2139 with HDFS/libhdfs properly. Each job uses its own connection to
2143 Read, write and erase an MTD character device (e.g.,
2144 :file:`/dev/mtd0`). Discards are treated as erases. Depending on the
2145 underlying device type, the I/O may have to go in a certain pattern,
2146 e.g., on NAND, writing sequentially to erase blocks and discarding
2147 before overwriting. The `trimwrite` mode works well for this
2151 Read and write using filesystem DAX to a file on a filesystem
2152 mounted with DAX on a persistent memory device through the PMDK
2156 Read and write using device DAX to a persistent memory device (e.g.,
2157 /dev/dax0.0) through the PMDK libpmem library.
2160 Prefix to specify loading an external I/O engine object file. Append
2161 the engine filename, e.g. ``ioengine=external:/tmp/foo.o`` to load
2162 ioengine :file:`foo.o` in :file:`/tmp`. The path can be either
2163 absolute or relative. See :file:`engines/skeleton_external.c` for
2164 details of writing an external I/O engine.
2167 Simply create the files and do no I/O to them. You still need to
2168 set `filesize` so that all the accounting still occurs, but no
2169 actual I/O will be done other than creating the file.
2172 Simply do stat() and do no I/O to the file. You need to set 'filesize'
2173 and 'nrfiles', so that files will be created.
2174 This engine is to measure file lookup and meta data access.
2177 Simply delete the files by unlink() and do no I/O to them. You need to set 'filesize'
2178 and 'nrfiles', so that the files will be created.
2179 This engine is to measure file delete.
2182 Read and write using mmap I/O to a file on a filesystem
2183 mounted with DAX on a persistent memory device through the PMDK
2187 Synchronous read and write using DDN's Infinite Memory Engine (IME).
2188 This engine is very basic and issues calls to IME whenever an IO is
2192 Synchronous read and write using DDN's Infinite Memory Engine (IME).
2193 This engine uses iovecs and will try to stack as much IOs as possible
2194 (if the IOs are "contiguous" and the IO depth is not exceeded)
2195 before issuing a call to IME.
2198 Asynchronous read and write using DDN's Infinite Memory Engine (IME).
2199 This engine will try to stack as much IOs as possible by creating
2200 requests for IME. FIO will then decide when to commit these requests.
2203 Read and write iscsi lun with libiscsi.
2206 Read and write a Network Block Device (NBD).
2209 I/O engine supporting libcufile synchronous access to nvidia-fs and a
2210 GPUDirect Storage-supported filesystem. This engine performs
2211 I/O without transferring buffers between user-space and the kernel,
2212 unless :option:`verify` is set or :option:`cuda_io` is `posix`.
2213 :option:`iomem` must not be `cudamalloc`. This ioengine defines
2214 engine specific options.
2217 I/O engine supporting asynchronous read and write operations to the
2218 DAOS File System (DFS) via libdfs.
2221 I/O engine supporting asynchronous read and write operations to
2222 NFS filesystems from userspace via libnfs. This is useful for
2223 achieving higher concurrency and thus throughput than is possible
2227 Execute 3rd party tools. Could be used to perform monitoring during jobs runtime.
2230 I/O engine using the xNVMe C API, for NVMe devices. The xnvme engine provides
2231 flexibility to access GNU/Linux Kernel NVMe driver via libaio, IOCTLs, io_uring,
2232 the SPDK NVMe driver, or your own custom NVMe driver. The xnvme engine includes
2233 engine specific options. (See https://xnvme.io).
2236 Use the libblkio library
2237 (https://gitlab.com/libblkio/libblkio). The specific
2238 *driver* to use must be set using
2239 :option:`libblkio_driver`. If
2240 :option:`mem`/:option:`iomem` is not specified, memory
2241 allocation is delegated to libblkio (and so is
2242 guaranteed to work with the selected *driver*). One
2243 libblkio instance is used per process, so all jobs
2244 setting option :option:`thread` will share a single
2245 instance (with one queue per thread) and must specify
2246 compatible options. Note that some drivers don't allow
2247 several instances to access the same device or file
2248 simultaneously, but allow it for threads.
2250 I/O engine specific parameters
2251 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2253 In addition, there are some parameters which are only valid when a specific
2254 :option:`ioengine` is in use. These are used identically to normal parameters,
2255 with the caveat that when used on the command line, they must come after the
2256 :option:`ioengine` that defines them is selected.
2258 .. option:: cmdprio_percentage=int[,int] : [io_uring] [libaio]
2260 Set the percentage of I/O that will be issued with the highest priority.
2261 Default: 0. A single value applies to reads and writes. Comma-separated
2262 values may be specified for reads and writes. For this option to be
2263 effective, NCQ priority must be supported and enabled, and the :option:`direct`
2264 option must be set. fio must also be run as the root user. Unlike
2265 slat/clat/lat stats, which can be tracked and reported independently, per
2266 priority stats only track and report a single type of latency. By default,
2267 completion latency (clat) will be reported, if :option:`lat_percentiles` is
2268 set, total latency (lat) will be reported.
2270 .. option:: cmdprio_class=int[,int] : [io_uring] [libaio]
2272 Set the I/O priority class to use for I/Os that must be issued with
2273 a priority when :option:`cmdprio_percentage` or
2274 :option:`cmdprio_bssplit` is set. If not specified when
2275 :option:`cmdprio_percentage` or :option:`cmdprio_bssplit` is set,
2276 this defaults to the highest priority class. A single value applies
2277 to reads and writes. Comma-separated values may be specified for
2278 reads and writes. See :manpage:`ionice(1)`. See also the
2279 :option:`prioclass` option.
2281 .. option:: cmdprio=int[,int] : [io_uring] [libaio]
2283 Set the I/O priority value to use for I/Os that must be issued with
2284 a priority when :option:`cmdprio_percentage` or
2285 :option:`cmdprio_bssplit` is set. If not specified when
2286 :option:`cmdprio_percentage` or :option:`cmdprio_bssplit` is set,
2288 Linux limits us to a positive value between 0 and 7, with 0 being the
2289 highest. A single value applies to reads and writes. Comma-separated
2290 values may be specified for reads and writes. See :manpage:`ionice(1)`.
2291 Refer to an appropriate manpage for other operating systems since
2292 meaning of priority may differ. See also the :option:`prio` option.
2294 .. option:: cmdprio_bssplit=str[,str] : [io_uring] [libaio]
2296 To get a finer control over I/O priority, this option allows
2297 specifying the percentage of IOs that must have a priority set
2298 depending on the block size of the IO. This option is useful only
2299 when used together with the :option:`bssplit` option, that is,
2300 multiple different block sizes are used for reads and writes.
2302 The first accepted format for this option is the same as the format of
2303 the :option:`bssplit` option:
2305 cmdprio_bssplit=blocksize/percentage:blocksize/percentage
2307 In this case, each entry will use the priority class and priority
2308 level defined by the options :option:`cmdprio_class` and
2309 :option:`cmdprio` respectively.
2311 The second accepted format for this option is:
2313 cmdprio_bssplit=blocksize/percentage/class/level:blocksize/percentage/class/level
2315 In this case, the priority class and priority level is defined inside
2316 each entry. In comparison with the first accepted format, the second
2317 accepted format does not restrict all entries to have the same priority
2318 class and priority level.
2320 For both formats, only the read and write data directions are supported,
2321 values for trim IOs are ignored. This option is mutually exclusive with
2322 the :option:`cmdprio_percentage` option.
2324 .. option:: fixedbufs : [io_uring] [io_uring_cmd]
2326 If fio is asked to do direct IO, then Linux will map pages for each
2327 IO call, and release them when IO is done. If this option is set, the
2328 pages are pre-mapped before IO is started. This eliminates the need to
2329 map and release for each IO. This is more efficient, and reduces the
2332 .. option:: nonvectored=int : [io_uring] [io_uring_cmd]
2334 With this option, fio will use non-vectored read/write commands, where
2335 address must contain the address directly. Default is -1.
2337 .. option:: force_async=int : [io_uring] [io_uring_cmd]
2339 Normal operation for io_uring is to try and issue an sqe as
2340 non-blocking first, and if that fails, execute it in an async manner.
2341 With this option set to N, then every N request fio will ask sqe to
2342 be issued in an async manner. Default is 0.
2344 .. option:: registerfiles : [io_uring] [io_uring_cmd]
2346 With this option, fio registers the set of files being used with the
2347 kernel. This avoids the overhead of managing file counts in the kernel,
2348 making the submission and completion part more lightweight. Required
2349 for the below :option:`sqthread_poll` option.
2351 .. option:: sqthread_poll : [io_uring] [io_uring_cmd] [xnvme]
2353 Normally fio will submit IO by issuing a system call to notify the
2354 kernel of available items in the SQ ring. If this option is set, the
2355 act of submitting IO will be done by a polling thread in the kernel.
2356 This frees up cycles for fio, at the cost of using more CPU in the
2357 system. As submission is just the time it takes to fill in the sqe
2358 entries and any syscall required to wake up the idle kernel thread,
2359 fio will not report submission latencies.
2361 .. option:: sqthread_poll_cpu=int : [io_uring] [io_uring_cmd]
2363 When :option:`sqthread_poll` is set, this option provides a way to
2364 define which CPU should be used for the polling thread.
2366 .. option:: cmd_type=str : [io_uring_cmd]
2368 Specifies the type of uring passthrough command to be used. Supported
2369 value is nvme. Default is nvme.
2373 [io_uring] [io_uring_cmd] [xnvme]
2375 If this option is set, fio will attempt to use polled IO completions.
2376 Normal IO completions generate interrupts to signal the completion of
2377 IO, polled completions do not. Hence they are require active reaping
2378 by the application. The benefits are more efficient IO for high IOPS
2379 scenarios, and lower latencies for low queue depth IO.
2383 Use poll queues. This is incompatible with
2384 :option:`libblkio_wait_mode=eventfd <libblkio_wait_mode>` and
2385 :option:`libblkio_force_enable_completion_eventfd`.
2389 Set RWF_HIPRI on I/O, indicating to the kernel that it's of higher priority
2394 If this option is set, fio will attempt to use polled IO completions.
2395 This will have a similar effect as (io_uring)hipri. Only SCSI READ and
2396 WRITE commands will have the SGV4_FLAG_HIPRI set (not UNMAP (trim) nor
2397 VERIFY). Older versions of the Linux sg driver that do not support
2398 hipri will simply ignore this flag and do normal IO. The Linux SCSI
2399 Low Level Driver (LLD) that "owns" the device also needs to support
2400 hipri (also known as iopoll and mq_poll). The MegaRAID driver is an
2401 example of a SCSI LLD. Default: clear (0) which does normal
2402 (interrupted based) IO.
2404 .. option:: userspace_reap : [libaio]
2406 Normally, with the libaio engine in use, fio will use the
2407 :manpage:`io_getevents(2)` system call to reap newly returned events. With
2408 this flag turned on, the AIO ring will be read directly from user-space to
2409 reap events. The reaping mode is only enabled when polling for a minimum of
2410 0 events (e.g. when :option:`iodepth_batch_complete` `=0`).
2412 .. option:: hipri_percentage : [pvsync2]
2414 When hipri is set this determines the probability of a pvsync2 I/O being high
2415 priority. The default is 100%.
2417 .. option:: nowait=bool : [pvsync2] [libaio] [io_uring] [io_uring_cmd]
2419 By default if a request cannot be executed immediately (e.g. resource starvation,
2420 waiting on locks) it is queued and the initiating process will be blocked until
2421 the required resource becomes free.
2423 This option sets the RWF_NOWAIT flag (supported from the 4.14 Linux kernel) and
2424 the call will return instantly with EAGAIN or a partial result rather than waiting.
2426 It is useful to also use ignore_error=EAGAIN when using this option.
2428 Note: glibc 2.27, 2.28 have a bug in syscall wrappers preadv2, pwritev2.
2429 They return EOPNOTSUP instead of EAGAIN.
2431 For cached I/O, using this option usually means a request operates only with
2432 cached data. Currently the RWF_NOWAIT flag does not supported for cached write.
2434 For direct I/O, requests will only succeed if cache invalidation isn't required,
2435 file blocks are fully allocated and the disk request could be issued immediately.
2437 .. option:: cpuload=int : [cpuio]
2439 Attempt to use the specified percentage of CPU cycles. This is a mandatory
2440 option when using cpuio I/O engine.
2442 .. option:: cpuchunks=int : [cpuio]
2444 Split the load into cycles of the given time. In microseconds.
2446 .. option:: cpumode=str : [cpuio]
2448 Specify how to stress the CPU. It can take these two values:
2451 This is the default where the CPU executes noop instructions.
2453 Replace the default noop instructions loop with a qsort algorithm to
2454 consume more energy.
2456 .. option:: exit_on_io_done=bool : [cpuio]
2458 Detect when I/O threads are done, then exit.
2460 .. option:: namenode=str : [libhdfs]
2462 The hostname or IP address of a HDFS cluster namenode to contact.
2464 .. option:: port=int
2468 The listening port of the HFDS cluster namenode.
2472 The TCP or UDP port to bind to or connect to. If this is used with
2473 :option:`numjobs` to spawn multiple instances of the same job type, then
2474 this will be the starting port number since fio will use a range of
2479 The port to use for RDMA-CM communication. This should be the same value
2480 on the client and the server side.
2482 .. option:: hostname=str : [netsplice] [net] [rdma]
2484 The hostname or IP address to use for TCP, UDP or RDMA-CM based I/O. If the job
2485 is a TCP listener or UDP reader, the hostname is not used and must be omitted
2486 unless it is a valid UDP multicast address.
2488 .. option:: serverip=str : [librpma_*]
2490 The IP address to be used for RDMA-CM based I/O.
2492 .. option:: direct_write_to_pmem=bool : [librpma_*]
2494 Set to 1 only when Direct Write to PMem from the remote host is possible.
2495 Otherwise, set to 0.
2497 .. option:: busy_wait_polling=bool : [librpma_*_server]
2499 Set to 0 to wait for completion instead of busy-wait polling completion.
2502 .. option:: interface=str : [netsplice] [net]
2504 The IP address of the network interface used to send or receive UDP
2507 .. option:: ttl=int : [netsplice] [net]
2509 Time-to-live value for outgoing UDP multicast packets. Default: 1.
2511 .. option:: nodelay=bool : [netsplice] [net]
2513 Set TCP_NODELAY on TCP connections.
2515 .. option:: protocol=str, proto=str : [netsplice] [net]
2517 The network protocol to use. Accepted values are:
2520 Transmission control protocol.
2522 Transmission control protocol V6.
2524 User datagram protocol.
2526 User datagram protocol V6.
2530 When the protocol is TCP or UDP, the port must also be given, as well as the
2531 hostname if the job is a TCP listener or UDP reader. For unix sockets, the
2532 normal :option:`filename` option should be used and the port is invalid.
2534 .. option:: listen : [netsplice] [net]
2536 For TCP network connections, tell fio to listen for incoming connections
2537 rather than initiating an outgoing connection. The :option:`hostname` must
2538 be omitted if this option is used.
2540 .. option:: pingpong : [netsplice] [net]
2542 Normally a network writer will just continue writing data, and a network
2543 reader will just consume packages. If ``pingpong=1`` is set, a writer will
2544 send its normal payload to the reader, then wait for the reader to send the
2545 same payload back. This allows fio to measure network latencies. The
2546 submission and completion latencies then measure local time spent sending or
2547 receiving, and the completion latency measures how long it took for the
2548 other end to receive and send back. For UDP multicast traffic
2549 ``pingpong=1`` should only be set for a single reader when multiple readers
2550 are listening to the same address.
2552 .. option:: window_size : [netsplice] [net]
2554 Set the desired socket buffer size for the connection.
2556 .. option:: mss : [netsplice] [net]
2558 Set the TCP maximum segment size (TCP_MAXSEG).
2560 .. option:: donorname=str : [e4defrag]
2562 File will be used as a block donor (swap extents between files).
2564 .. option:: inplace=int : [e4defrag]
2566 Configure donor file blocks allocation strategy:
2569 Default. Preallocate donor's file on init.
2571 Allocate space immediately inside defragment event, and free right
2574 .. option:: clustername=str : [rbd,rados]
2576 Specifies the name of the Ceph cluster.
2578 .. option:: rbdname=str : [rbd]
2580 Specifies the name of the RBD.
2582 .. option:: clientname=str : [rbd,rados]
2584 Specifies the username (without the 'client.' prefix) used to access the
2585 Ceph cluster. If the *clustername* is specified, the *clientname* shall be
2586 the full *type.id* string. If no type. prefix is given, fio will add
2587 'client.' by default.
2589 .. option:: conf=str : [rados]
2591 Specifies the configuration path of ceph cluster, so conf file does not
2592 have to be /etc/ceph/ceph.conf.
2594 .. option:: busy_poll=bool : [rbd,rados]
2596 Poll store instead of waiting for completion. Usually this provides better
2597 throughput at cost of higher(up to 100%) CPU utilization.
2599 .. option:: touch_objects=bool : [rados]
2601 During initialization, touch (create if do not exist) all objects (files).
2602 Touching all objects affects ceph caches and likely impacts test results.
2605 .. option:: pool=str :
2609 Specifies the name of the Ceph pool containing RBD or RADOS data.
2613 Specify the label or UUID of the DAOS pool to connect to.
2615 .. option:: cont=str : [dfs]
2617 Specify the label or UUID of the DAOS container to open.
2619 .. option:: chunk_size=int
2623 Specify a different chunk size (in bytes) for the dfs file.
2624 Use DAOS container's chunk size by default.
2628 The size of the chunk to use for each file.
2630 .. option:: object_class=str : [dfs]
2632 Specify a different object class for the dfs file.
2633 Use DAOS container's object class by default.
2635 .. option:: skip_bad=bool : [mtd]
2637 Skip operations against known bad blocks.
2639 .. option:: hdfsdirectory : [libhdfs]
2641 libhdfs will create chunk in this HDFS directory.
2643 .. option:: verb=str : [rdma]
2645 The RDMA verb to use on this side of the RDMA ioengine connection. Valid
2646 values are write, read, send and recv. These correspond to the equivalent
2647 RDMA verbs (e.g. write = rdma_write etc.). Note that this only needs to be
2648 specified on the client side of the connection. See the examples folder.
2650 .. option:: bindname=str : [rdma]
2652 The name to use to bind the local RDMA-CM connection to a local RDMA device.
2653 This could be a hostname or an IPv4 or IPv6 address. On the server side this
2654 will be passed into the rdma_bind_addr() function and on the client site it
2655 will be used in the rdma_resolve_add() function. This can be useful when
2656 multiple paths exist between the client and the server or in certain loopback
2659 .. option:: stat_type=str : [filestat]
2661 Specify stat system call type to measure lookup/getattr performance.
2662 Default is **stat** for :manpage:`stat(2)`.
2664 .. option:: readfua=bool : [sg]
2666 With readfua option set to 1, read operations include
2667 the force unit access (fua) flag. Default is 0.
2669 .. option:: writefua=bool : [sg]
2671 With writefua option set to 1, write operations include
2672 the force unit access (fua) flag. Default is 0.
2674 .. option:: sg_write_mode=str : [sg]
2676 Specify the type of write commands to issue. This option can take three values:
2679 This is the default where write opcodes are issued as usual.
2680 **write_and_verify**
2681 Issue WRITE AND VERIFY commands. The BYTCHK bit is set to 0. This
2682 directs the device to carry out a medium verification with no data
2683 comparison. The writefua option is ignored with this selection.
2685 This option is deprecated. Use write_and_verify instead.
2687 Issue WRITE SAME commands. This transfers a single block to the device
2688 and writes this same block of data to a contiguous sequence of LBAs
2689 beginning at the specified offset. fio's block size parameter specifies
2690 the amount of data written with each command. However, the amount of data
2691 actually transferred to the device is equal to the device's block
2692 (sector) size. For a device with 512 byte sectors, blocksize=8k will
2693 write 16 sectors with each command. fio will still generate 8k of data
2694 for each command but only the first 512 bytes will be used and
2695 transferred to the device. The writefua option is ignored with this
2698 This option is deprecated. Use write_same instead.
2700 Issue WRITE SAME(16) commands as above but with the No Data Output
2701 Buffer (NDOB) bit set. No data will be transferred to the device with
2702 this bit set. Data written will be a pre-determined pattern such as
2705 Issue WRITE STREAM(16) commands. Use the **stream_id** option to specify
2706 the stream identifier.
2707 **verify_bytchk_00**
2708 Issue VERIFY commands with BYTCHK set to 00. This directs the
2709 device to carry out a medium verification with no data comparison.
2710 **verify_bytchk_01**
2711 Issue VERIFY commands with BYTCHK set to 01. This directs the device to
2712 compare the data on the device with the data transferred to the device.
2713 **verify_bytchk_11**
2714 Issue VERIFY commands with BYTCHK set to 11. This transfers a
2715 single block to the device and compares the contents of this block with the
2716 data on the device beginning at the specified offset. fio's block size
2717 parameter specifies the total amount of data compared with this command.
2718 However, only one block (sector) worth of data is transferred to the device.
2719 This is similar to the WRITE SAME command except that data is compared instead
2722 .. option:: stream_id=int : [sg]
2724 Set the stream identifier for WRITE STREAM commands. If this is set to 0 (which is not
2725 a valid stream identifier) fio will open a stream and then close it when done. Default
2728 .. option:: http_host=str : [http]
2730 Hostname to connect to. For S3, this could be the bucket hostname.
2731 Default is **localhost**
2733 .. option:: http_user=str : [http]
2735 Username for HTTP authentication.
2737 .. option:: http_pass=str : [http]
2739 Password for HTTP authentication.
2741 .. option:: https=str : [http]
2743 Enable HTTPS instead of http. *on* enables HTTPS; *insecure*
2744 will enable HTTPS, but disable SSL peer verification (use with
2745 caution!). Default is **off**
2747 .. option:: http_mode=str : [http]
2749 Which HTTP access mode to use: *webdav*, *swift*, or *s3*.
2750 Default is **webdav**
2752 .. option:: http_s3_region=str : [http]
2754 The S3 region/zone string.
2755 Default is **us-east-1**
2757 .. option:: http_s3_key=str : [http]
2761 .. option:: http_s3_keyid=str : [http]
2763 The S3 key/access id.
2765 .. option:: http_s3_sse_customer_key=str : [http]
2767 The encryption customer key in SSE server side.
2769 .. option:: http_s3_sse_customer_algorithm=str : [http]
2771 The encryption customer algorithm in SSE server side.
2772 Default is **AES256**
2774 .. option:: http_s3_storage_class=str : [http]
2776 Which storage class to access. User-customizable settings.
2777 Default is **STANDARD**
2779 .. option:: http_swift_auth_token=str : [http]
2781 The Swift auth token. See the example configuration file on how
2784 .. option:: http_verbose=int : [http]
2786 Enable verbose requests from libcurl. Useful for debugging. 1
2787 turns on verbose logging from libcurl, 2 additionally enables
2788 HTTP IO tracing. Default is **0**
2790 .. option:: uri=str : [nbd]
2792 Specify the NBD URI of the server to test. The string
2793 is a standard NBD URI
2794 (see https://github.com/NetworkBlockDevice/nbd/tree/master/doc).
2795 Example URIs: nbd://localhost:10809
2796 nbd+unix:///?socket=/tmp/socket
2797 nbds://tlshost/exportname
2799 .. option:: gpu_dev_ids=str : [libcufile]
2801 Specify the GPU IDs to use with CUDA. This is a colon-separated list of
2802 int. GPUs are assigned to workers roundrobin. Default is 0.
2804 .. option:: cuda_io=str : [libcufile]
2806 Specify the type of I/O to use with CUDA. Default is **cufile**.
2809 Use libcufile and nvidia-fs. This option performs I/O directly
2810 between a GPUDirect Storage filesystem and GPU buffers,
2811 avoiding use of a bounce buffer. If :option:`verify` is set,
2812 cudaMemcpy is used to copy verificaton data between RAM and GPU.
2813 Verification data is copied from RAM to GPU before a write
2814 and from GPU to RAM after a read. :option:`direct` must be 1.
2816 Use POSIX to perform I/O with a RAM buffer, and use cudaMemcpy
2817 to transfer data between RAM and the GPUs. Data is copied from
2818 GPU to RAM before a write and copied from RAM to GPU after a
2819 read. :option:`verify` does not affect use of cudaMemcpy.
2821 .. option:: nfs_url=str : [nfs]
2823 URL in libnfs format, eg nfs://<server|ipv4|ipv6>/path[?arg=val[&arg=val]*]
2824 Refer to the libnfs README for more details.
2826 .. option:: program=str : [exec]
2828 Specify the program to execute.
2830 .. option:: arguments=str : [exec]
2832 Specify arguments to pass to program.
2833 Some special variables can be expanded to pass fio's job details to the program.
2836 Replaced by the duration of the job in seconds.
2838 Replaced by the name of the job.
2840 .. option:: grace_time=int : [exec]
2842 Specify the time between the SIGTERM and SIGKILL signals. Default is 1 second.
2844 .. option:: std_redirect=bool : [exec]
2846 If set, stdout and stderr streams are redirected to files named from the job name. Default is true.
2848 .. option:: xnvme_async=str : [xnvme]
2850 Select the xnvme async command interface. This can take these values.
2853 This is default and use to emulate asynchronous I/O by using a
2854 single thread to create a queue pair on top of a synchronous
2855 I/O interface using the NVMe driver IOCTL.
2857 Emulate an asynchronous I/O interface with a pool of userspace
2858 threads on top of a synchronous I/O interface using the NVMe
2859 driver IOCTL. By default four threads are used.
2861 Linux native asynchronous I/O interface which supports both
2862 direct and buffered I/O.
2864 Fast Linux native asynchronous I/O interface for NVMe pass
2865 through commands. This only works with NVMe character device
2868 Use Linux aio for Asynchronous I/O.
2870 Use the posix asynchronous I/O interface to perform one or
2871 more I/O operations asynchronously.
2873 Use the user-space VFIO-based backend, implemented using
2874 libvfn instead of SPDK.
2876 Do not transfer any data; just pretend to. This is mainly used
2877 for introspective performance evaluation.
2879 .. option:: xnvme_sync=str : [xnvme]
2881 Select the xnvme synchronous command interface. This can take these values.
2884 This is default and uses Linux NVMe Driver ioctl() for
2887 This supports regular as well as vectored pread() and pwrite()
2890 This is the same as psync except that it also supports zone
2891 management commands using Linux block layer IOCTLs.
2893 .. option:: xnvme_admin=str : [xnvme]
2895 Select the xnvme admin command interface. This can take these values.
2898 This is default and uses linux NVMe Driver ioctl() for admin
2901 Use Linux Block Layer ioctl() and sysfs for admin commands.
2903 .. option:: xnvme_dev_nsid=int : [xnvme]
2905 xnvme namespace identifier for userspace NVMe driver, SPDK or vfio.
2907 .. option:: xnvme_dev_subnqn=str : [xnvme]
2909 Sets the subsystem NQN for fabrics. This is for xNVMe to utilize a
2910 fabrics target with multiple systems.
2912 .. option:: xnvme_mem=str : [xnvme]
2914 Select the xnvme memory backend. This can take these values.
2917 This is the default posix memory backend for linux NVMe driver.
2919 Use hugepages, instead of existing posix memory backend. The
2920 memory backend uses hugetlbfs. This require users to allocate
2921 hugepages, mount hugetlbfs and set an enviornment variable for
2924 Uses SPDK's memory allocator.
2926 Uses libvfn's memory allocator. This also specifies the use
2927 of libvfn backend instead of SPDK.
2929 .. option:: xnvme_iovec=int : [xnvme]
2931 If this option is set. xnvme will use vectored read/write commands.
2933 .. option:: libblkio_driver=str : [libblkio]
2935 The libblkio *driver* to use. Different drivers access devices through
2936 different underlying interfaces. Available drivers depend on the
2937 libblkio version in use and are listed at
2938 https://libblkio.gitlab.io/libblkio/blkio.html#drivers
2940 .. option:: libblkio_path=str : [libblkio]
2942 Sets the value of the driver-specific "path" property before connecting
2943 the libblkio instance, which identifies the target device or file on
2944 which to perform I/O. Its exact semantics are driver-dependent and not
2945 all drivers may support it; see
2946 https://libblkio.gitlab.io/libblkio/blkio.html#drivers
2948 .. option:: libblkio_pre_connect_props=str : [libblkio]
2950 A colon-separated list of additional libblkio properties to be set after
2951 creating but before connecting the libblkio instance. Each property must
2952 have the format ``<name>=<value>``. Colons can be escaped as ``\:``.
2953 These are set after the engine sets any other properties, so those can
2954 be overriden. Available properties depend on the libblkio version in use
2956 https://libblkio.gitlab.io/libblkio/blkio.html#properties
2958 .. option:: libblkio_num_entries=int : [libblkio]
2960 Sets the value of the driver-specific "num-entries" property before
2961 starting the libblkio instance. Its exact semantics are driver-dependent
2962 and not all drivers may support it; see
2963 https://libblkio.gitlab.io/libblkio/blkio.html#drivers
2965 .. option:: libblkio_queue_size=int : [libblkio]
2967 Sets the value of the driver-specific "queue-size" property before
2968 starting the libblkio instance. Its exact semantics are driver-dependent
2969 and not all drivers may support it; see
2970 https://libblkio.gitlab.io/libblkio/blkio.html#drivers
2972 .. option:: libblkio_pre_start_props=str : [libblkio]
2974 A colon-separated list of additional libblkio properties to be set after
2975 connecting but before starting the libblkio instance. Each property must
2976 have the format ``<name>=<value>``. Colons can be escaped as ``\:``.
2977 These are set after the engine sets any other properties, so those can
2978 be overriden. Available properties depend on the libblkio version in use
2980 https://libblkio.gitlab.io/libblkio/blkio.html#properties
2982 .. option:: libblkio_vectored : [libblkio]
2984 Submit vectored read and write requests.
2986 .. option:: libblkio_write_zeroes_on_trim : [libblkio]
2988 Submit trims as "write zeroes" requests instead of discard requests.
2990 .. option:: libblkio_wait_mode=str : [libblkio]
2992 How to wait for completions:
2995 Use a blocking call to ``blkioq_do_io()``.
2997 Use a blocking call to ``read()`` on the completion eventfd.
2999 Use a busy loop with a non-blocking call to ``blkioq_do_io()``.
3001 .. option:: libblkio_force_enable_completion_eventfd : [libblkio]
3003 Enable the queue's completion eventfd even when unused. This may impact
3004 performance. The default is to enable it only if
3005 :option:`libblkio_wait_mode=eventfd <libblkio_wait_mode>`.
3010 .. option:: iodepth=int
3012 Number of I/O units to keep in flight against the file. Note that
3013 increasing *iodepth* beyond 1 will not affect synchronous ioengines (except
3014 for small degrees when :option:`verify_async` is in use). Even async
3015 engines may impose OS restrictions causing the desired depth not to be
3016 achieved. This may happen on Linux when using libaio and not setting
3017 :option:`direct`\=1, since buffered I/O is not async on that OS. Keep an
3018 eye on the I/O depth distribution in the fio output to verify that the
3019 achieved depth is as expected. Default: 1.
3021 .. option:: iodepth_batch_submit=int, iodepth_batch=int
3023 This defines how many pieces of I/O to submit at once. It defaults to 1
3024 which means that we submit each I/O as soon as it is available, but can be
3025 raised to submit bigger batches of I/O at the time. If it is set to 0 the
3026 :option:`iodepth` value will be used.
3028 .. option:: iodepth_batch_complete_min=int, iodepth_batch_complete=int
3030 This defines how many pieces of I/O to retrieve at once. It defaults to 1
3031 which means that we'll ask for a minimum of 1 I/O in the retrieval process
3032 from the kernel. The I/O retrieval will go on until we hit the limit set by
3033 :option:`iodepth_low`. If this variable is set to 0, then fio will always
3034 check for completed events before queuing more I/O. This helps reduce I/O
3035 latency, at the cost of more retrieval system calls.
3037 .. option:: iodepth_batch_complete_max=int
3039 This defines maximum pieces of I/O to retrieve at once. This variable should
3040 be used along with :option:`iodepth_batch_complete_min`\=int variable,
3041 specifying the range of min and max amount of I/O which should be
3042 retrieved. By default it is equal to the :option:`iodepth_batch_complete_min`
3047 iodepth_batch_complete_min=1
3048 iodepth_batch_complete_max=<iodepth>
3050 which means that we will retrieve at least 1 I/O and up to the whole
3051 submitted queue depth. If none of I/O has been completed yet, we will wait.
3055 iodepth_batch_complete_min=0
3056 iodepth_batch_complete_max=<iodepth>
3058 which means that we can retrieve up to the whole submitted queue depth, but
3059 if none of I/O has been completed yet, we will NOT wait and immediately exit
3060 the system call. In this example we simply do polling.
3062 .. option:: iodepth_low=int
3064 The low water mark indicating when to start filling the queue
3065 again. Defaults to the same as :option:`iodepth`, meaning that fio will
3066 attempt to keep the queue full at all times. If :option:`iodepth` is set to
3067 e.g. 16 and *iodepth_low* is set to 4, then after fio has filled the queue of
3068 16 requests, it will let the depth drain down to 4 before starting to fill
3071 .. option:: serialize_overlap=bool
3073 Serialize in-flight I/Os that might otherwise cause or suffer from data races.
3074 When two or more I/Os are submitted simultaneously, there is no guarantee that
3075 the I/Os will be processed or completed in the submitted order. Further, if
3076 two or more of those I/Os are writes, any overlapping region between them can
3077 become indeterminate/undefined on certain storage. These issues can cause
3078 verification to fail erratically when at least one of the racing I/Os is
3079 changing data and the overlapping region has a non-zero size. Setting
3080 ``serialize_overlap`` tells fio to avoid provoking this behavior by explicitly
3081 serializing in-flight I/Os that have a non-zero overlap. Note that setting
3082 this option can reduce both performance and the :option:`iodepth` achieved.
3084 This option only applies to I/Os issued for a single job except when it is
3085 enabled along with :option:`io_submit_mode`\=offload. In offload mode, fio
3086 will check for overlap among all I/Os submitted by offload jobs with :option:`serialize_overlap`
3091 .. option:: io_submit_mode=str
3093 This option controls how fio submits the I/O to the I/O engine. The default
3094 is `inline`, which means that the fio job threads submit and reap I/O
3095 directly. If set to `offload`, the job threads will offload I/O submission
3096 to a dedicated pool of I/O threads. This requires some coordination and thus
3097 has a bit of extra overhead, especially for lower queue depth I/O where it
3098 can increase latencies. The benefit is that fio can manage submission rates
3099 independently of the device completion rates. This avoids skewed latency
3100 reporting if I/O gets backed up on the device side (the coordinated omission
3101 problem). Note that this option cannot reliably be used with async IO
3108 .. option:: thinktime=time
3110 Stall the job for the specified period of time after an I/O has completed before issuing the
3111 next. May be used to simulate processing being done by an application.
3112 When the unit is omitted, the value is interpreted in microseconds. See
3113 :option:`thinktime_blocks`, :option:`thinktime_iotime` and :option:`thinktime_spin`.
3115 .. option:: thinktime_spin=time
3117 Only valid if :option:`thinktime` is set - pretend to spend CPU time doing
3118 something with the data received, before falling back to sleeping for the
3119 rest of the period specified by :option:`thinktime`. When the unit is
3120 omitted, the value is interpreted in microseconds.
3122 .. option:: thinktime_blocks=int
3124 Only valid if :option:`thinktime` is set - control how many blocks to issue,
3125 before waiting :option:`thinktime` usecs. If not set, defaults to 1 which will make
3126 fio wait :option:`thinktime` usecs after every block. This effectively makes any
3127 queue depth setting redundant, since no more than 1 I/O will be queued
3128 before we have to complete it and do our :option:`thinktime`. In other words, this
3129 setting effectively caps the queue depth if the latter is larger.
3131 .. option:: thinktime_blocks_type=str
3133 Only valid if :option:`thinktime` is set - control how :option:`thinktime_blocks`
3134 triggers. The default is `complete`, which triggers thinktime when fio completes
3135 :option:`thinktime_blocks` blocks. If this is set to `issue`, then the trigger happens
3138 .. option:: thinktime_iotime=time
3140 Only valid if :option:`thinktime` is set - control :option:`thinktime`
3141 interval by time. The :option:`thinktime` stall is repeated after IOs
3142 are executed for :option:`thinktime_iotime`. For example,
3143 ``--thinktime_iotime=9s --thinktime=1s`` repeat 10-second cycle with IOs
3144 for 9 seconds and stall for 1 second. When the unit is omitted,
3145 :option:`thinktime_iotime` is interpreted as a number of seconds. If
3146 this option is used together with :option:`thinktime_blocks`, the
3147 :option:`thinktime` stall is repeated after :option:`thinktime_iotime`
3148 or after :option:`thinktime_blocks` IOs, whichever happens first.
3150 .. option:: rate=int[,int][,int]
3152 Cap the bandwidth used by this job. The number is in bytes/sec, the normal
3153 suffix rules apply. Comma-separated values may be specified for reads,
3154 writes, and trims as described in :option:`blocksize`.
3156 For example, using `rate=1m,500k` would limit reads to 1MiB/sec and writes to
3157 500KiB/sec. Capping only reads or writes can be done with `rate=,500k` or
3158 `rate=500k,` where the former will only limit writes (to 500KiB/sec) and the
3159 latter will only limit reads.
3161 .. option:: rate_min=int[,int][,int]
3163 Tell fio to do whatever it can to maintain at least this bandwidth. Failing
3164 to meet this requirement will cause the job to exit. Comma-separated values
3165 may be specified for reads, writes, and trims as described in
3166 :option:`blocksize`.
3168 .. option:: rate_iops=int[,int][,int]
3170 Cap the bandwidth to this number of IOPS. Basically the same as
3171 :option:`rate`, just specified independently of bandwidth. If the job is
3172 given a block size range instead of a fixed value, the smallest block size
3173 is used as the metric. Comma-separated values may be specified for reads,
3174 writes, and trims as described in :option:`blocksize`.
3176 .. option:: rate_iops_min=int[,int][,int]
3178 If fio doesn't meet this rate of I/O, it will cause the job to exit.
3179 Comma-separated values may be specified for reads, writes, and trims as
3180 described in :option:`blocksize`.
3182 .. option:: rate_process=str
3184 This option controls how fio manages rated I/O submissions. The default is
3185 `linear`, which submits I/O in a linear fashion with fixed delays between
3186 I/Os that gets adjusted based on I/O completion rates. If this is set to
3187 `poisson`, fio will submit I/O based on a more real world random request
3188 flow, known as the Poisson process
3189 (https://en.wikipedia.org/wiki/Poisson_point_process). The lambda will be
3190 10^6 / IOPS for the given workload.
3192 .. option:: rate_ignore_thinktime=bool
3194 By default, fio will attempt to catch up to the specified rate setting,
3195 if any kind of thinktime setting was used. If this option is set, then
3196 fio will ignore the thinktime and continue doing IO at the specified
3197 rate, instead of entering a catch-up mode after thinktime is done.
3203 .. option:: latency_target=time
3205 If set, fio will attempt to find the max performance point that the given
3206 workload will run at while maintaining a latency below this target. When
3207 the unit is omitted, the value is interpreted in microseconds. See
3208 :option:`latency_window` and :option:`latency_percentile`.
3210 .. option:: latency_window=time
3212 Used with :option:`latency_target` to specify the sample window that the job
3213 is run at varying queue depths to test the performance. When the unit is
3214 omitted, the value is interpreted in microseconds.
3216 .. option:: latency_percentile=float
3218 The percentage of I/Os that must fall within the criteria specified by
3219 :option:`latency_target` and :option:`latency_window`. If not set, this
3220 defaults to 100.0, meaning that all I/Os must be equal or below to the value
3221 set by :option:`latency_target`.
3223 .. option:: latency_run=bool
3225 Used with :option:`latency_target`. If false (default), fio will find
3226 the highest queue depth that meets :option:`latency_target` and exit. If
3227 true, fio will continue running and try to meet :option:`latency_target`
3228 by adjusting queue depth.
3230 .. option:: max_latency=time[,time][,time]
3232 If set, fio will exit the job with an ETIMEDOUT error if it exceeds this
3233 maximum latency. When the unit is omitted, the value is interpreted in
3234 microseconds. Comma-separated values may be specified for reads, writes,
3235 and trims as described in :option:`blocksize`.
3237 .. option:: rate_cycle=int
3239 Average bandwidth for :option:`rate` and :option:`rate_min` over this number
3240 of milliseconds. Defaults to 1000.
3246 .. option:: write_iolog=str
3248 Write the issued I/O patterns to the specified file. See
3249 :option:`read_iolog`. Specify a separate file for each job, otherwise the
3250 iologs will be interspersed and the file may be corrupt. This file will
3251 be opened in append mode.
3253 .. option:: read_iolog=str
3255 Open an iolog with the specified filename and replay the I/O patterns it
3256 contains. This can be used to store a workload and replay it sometime
3257 later. The iolog given may also be a blktrace binary file, which allows fio
3258 to replay a workload captured by :command:`blktrace`. See
3259 :manpage:`blktrace(8)` for how to capture such logging data. For blktrace
3260 replay, the file needs to be turned into a blkparse binary data file first
3261 (``blkparse <device> -o /dev/null -d file_for_fio.bin``).
3262 You can specify a number of files by separating the names with a ':'
3263 character. See the :option:`filename` option for information on how to
3264 escape ':' characters within the file names. These files will
3265 be sequentially assigned to job clones created by :option:`numjobs`.
3266 '-' is a reserved name, meaning read from stdin, notably if
3267 :option:`filename` is set to '-' which means stdin as well, then
3268 this flag can't be set to '-'.
3270 .. option:: read_iolog_chunked=bool
3272 Determines how iolog is read. If false(default) entire :option:`read_iolog`
3273 will be read at once. If selected true, input from iolog will be read
3274 gradually. Useful when iolog is very large, or it is generated.
3276 .. option:: merge_blktrace_file=str
3278 When specified, rather than replaying the logs passed to :option:`read_iolog`,
3279 the logs go through a merge phase which aggregates them into a single
3280 blktrace. The resulting file is then passed on as the :option:`read_iolog`
3281 parameter. The intention here is to make the order of events consistent.
3282 This limits the influence of the scheduler compared to replaying multiple
3283 blktraces via concurrent jobs.
3285 .. option:: merge_blktrace_scalars=float_list
3287 This is a percentage based option that is index paired with the list of
3288 files passed to :option:`read_iolog`. When merging is performed, scale
3289 the time of each event by the corresponding amount. For example,
3290 ``--merge_blktrace_scalars="50:100"`` runs the first trace in halftime
3291 and the second trace in realtime. This knob is separately tunable from
3292 :option:`replay_time_scale` which scales the trace during runtime and
3293 does not change the output of the merge unlike this option.
3295 .. option:: merge_blktrace_iters=float_list
3297 This is a whole number option that is index paired with the list of files
3298 passed to :option:`read_iolog`. When merging is performed, run each trace
3299 for the specified number of iterations. For example,
3300 ``--merge_blktrace_iters="2:1"`` runs the first trace for two iterations
3301 and the second trace for one iteration.
3303 .. option:: replay_no_stall=bool
3305 When replaying I/O with :option:`read_iolog` the default behavior is to
3306 attempt to respect the timestamps within the log and replay them with the
3307 appropriate delay between IOPS. By setting this variable fio will not
3308 respect the timestamps and attempt to replay them as fast as possible while
3309 still respecting ordering. The result is the same I/O pattern to a given
3310 device, but different timings.
3312 .. option:: replay_time_scale=int
3314 When replaying I/O with :option:`read_iolog`, fio will honor the
3315 original timing in the trace. With this option, it's possible to scale
3316 the time. It's a percentage option, if set to 50 it means run at 50%
3317 the original IO rate in the trace. If set to 200, run at twice the
3318 original IO rate. Defaults to 100.
3320 .. option:: replay_redirect=str
3322 While replaying I/O patterns using :option:`read_iolog` the default behavior
3323 is to replay the IOPS onto the major/minor device that each IOP was recorded
3324 from. This is sometimes undesirable because on a different machine those
3325 major/minor numbers can map to a different device. Changing hardware on the
3326 same system can also result in a different major/minor mapping.
3327 ``replay_redirect`` causes all I/Os to be replayed onto the single specified
3328 device regardless of the device it was recorded
3329 from. i.e. :option:`replay_redirect`\= :file:`/dev/sdc` would cause all I/O
3330 in the blktrace or iolog to be replayed onto :file:`/dev/sdc`. This means
3331 multiple devices will be replayed onto a single device, if the trace
3332 contains multiple devices. If you want multiple devices to be replayed
3333 concurrently to multiple redirected devices you must blkparse your trace
3334 into separate traces and replay them with independent fio invocations.
3335 Unfortunately this also breaks the strict time ordering between multiple
3338 .. option:: replay_align=int
3340 Force alignment of the byte offsets in a trace to this value. The value
3341 must be a power of 2.
3343 .. option:: replay_scale=int
3345 Scale byte offsets down by this factor when replaying traces. Should most
3346 likely use :option:`replay_align` as well.
3348 .. option:: replay_skip=str
3350 Sometimes it's useful to skip certain IO types in a replay trace.
3351 This could be, for instance, eliminating the writes in the trace.
3352 Or not replaying the trims/discards, if you are redirecting to
3353 a device that doesn't support them. This option takes a comma
3354 separated list of read, write, trim, sync.
3357 Threads, processes and job synchronization
3358 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3362 Fio defaults to creating jobs by using fork, however if this option is
3363 given, fio will create jobs by using POSIX Threads' function
3364 :manpage:`pthread_create(3)` to create threads instead.
3366 .. option:: wait_for=str
3368 If set, the current job won't be started until all workers of the specified
3369 waitee job are done.
3371 ``wait_for`` operates on the job name basis, so there are a few
3372 limitations. First, the waitee must be defined prior to the waiter job
3373 (meaning no forward references). Second, if a job is being referenced as a
3374 waitee, it must have a unique name (no duplicate waitees).
3376 .. option:: nice=int
3378 Run the job with the given nice value. See man :manpage:`nice(2)`.
3380 On Windows, values less than -15 set the process class to "High"; -1 through
3381 -15 set "Above Normal"; 1 through 15 "Below Normal"; and above 15 "Idle"
3384 .. option:: prio=int
3386 Set the I/O priority value of this job. Linux limits us to a positive value
3387 between 0 and 7, with 0 being the highest. See man
3388 :manpage:`ionice(1)`. Refer to an appropriate manpage for other operating
3389 systems since meaning of priority may differ. For per-command priority
3390 setting, see I/O engine specific :option:`cmdprio_percentage` and
3391 :option:`cmdprio` options.
3393 .. option:: prioclass=int
3395 Set the I/O priority class. See man :manpage:`ionice(1)`. For per-command
3396 priority setting, see I/O engine specific :option:`cmdprio_percentage`
3397 and :option:`cmdprio_class` options.
3399 .. option:: cpus_allowed=str
3401 Controls the same options as :option:`cpumask`, but accepts a textual
3402 specification of the permitted CPUs instead and CPUs are indexed from 0. So
3403 to use CPUs 0 and 5 you would specify ``cpus_allowed=0,5``. This option also
3404 allows a range of CPUs to be specified -- say you wanted a binding to CPUs
3405 0, 5, and 8 to 15, you would set ``cpus_allowed=0,5,8-15``.
3407 On Windows, when ``cpus_allowed`` is unset only CPUs from fio's current
3408 processor group will be used and affinity settings are inherited from the
3409 system. An fio build configured to target Windows 7 makes options that set
3410 CPUs processor group aware and values will set both the processor group
3411 and a CPU from within that group. For example, on a system where processor
3412 group 0 has 40 CPUs and processor group 1 has 32 CPUs, ``cpus_allowed``
3413 values between 0 and 39 will bind CPUs from processor group 0 and
3414 ``cpus_allowed`` values between 40 and 71 will bind CPUs from processor
3415 group 1. When using ``cpus_allowed_policy=shared`` all CPUs specified by a
3416 single ``cpus_allowed`` option must be from the same processor group. For
3417 Windows fio builds not built for Windows 7, CPUs will only be selected from
3418 (and be relative to) whatever processor group fio happens to be running in
3419 and CPUs from other processor groups cannot be used.
3421 .. option:: cpus_allowed_policy=str
3423 Set the policy of how fio distributes the CPUs specified by
3424 :option:`cpus_allowed` or :option:`cpumask`. Two policies are supported:
3427 All jobs will share the CPU set specified.
3429 Each job will get a unique CPU from the CPU set.
3431 **shared** is the default behavior, if the option isn't specified. If
3432 **split** is specified, then fio will assign one cpu per job. If not
3433 enough CPUs are given for the jobs listed, then fio will roundrobin the CPUs
3436 .. option:: cpumask=int
3438 Set the CPU affinity of this job. The parameter given is a bit mask of
3439 allowed CPUs the job may run on. So if you want the allowed CPUs to be 1
3440 and 5, you would pass the decimal value of (1 << 1 | 1 << 5), or 34. See man
3441 :manpage:`sched_setaffinity(2)`. This may not work on all supported
3442 operating systems or kernel versions. This option doesn't work well for a
3443 higher CPU count than what you can store in an integer mask, so it can only
3444 control cpus 1-32. For boxes with larger CPU counts, use
3445 :option:`cpus_allowed`.
3447 .. option:: numa_cpu_nodes=str
3449 Set this job running on specified NUMA nodes' CPUs. The arguments allow
3450 comma delimited list of cpu numbers, A-B ranges, or `all`. Note, to enable
3451 NUMA options support, fio must be built on a system with libnuma-dev(el)
3454 .. option:: numa_mem_policy=str
3456 Set this job's memory policy and corresponding NUMA nodes. Format of the
3461 ``mode`` is one of the following memory policies: ``default``, ``prefer``,
3462 ``bind``, ``interleave`` or ``local``. For ``default`` and ``local`` memory
3463 policies, no node needs to be specified. For ``prefer``, only one node is
3464 allowed. For ``bind`` and ``interleave`` the ``nodelist`` may be as
3465 follows: a comma delimited list of numbers, A-B ranges, or `all`.
3467 .. option:: cgroup=str
3469 Add job to this control group. If it doesn't exist, it will be created. The
3470 system must have a mounted cgroup blkio mount point for this to work. If
3471 your system doesn't have it mounted, you can do so with::
3473 # mount -t cgroup -o blkio none /cgroup
3475 .. option:: cgroup_weight=int
3477 Set the weight of the cgroup to this value. See the documentation that comes
3478 with the kernel, allowed values are in the range of 100..1000.
3480 .. option:: cgroup_nodelete=bool
3482 Normally fio will delete the cgroups it has created after the job
3483 completion. To override this behavior and to leave cgroups around after the
3484 job completion, set ``cgroup_nodelete=1``. This can be useful if one wants
3485 to inspect various cgroup files after job completion. Default: false.
3487 .. option:: flow_id=int
3489 The ID of the flow. If not specified, it defaults to being a global
3490 flow. See :option:`flow`.
3492 .. option:: flow=int
3494 Weight in token-based flow control. If this value is used, then fio
3495 regulates the activity between two or more jobs sharing the same
3496 flow_id. Fio attempts to keep each job activity proportional to other
3497 jobs' activities in the same flow_id group, with respect to requested
3498 weight per job. That is, if one job has `flow=3', another job has
3499 `flow=2' and another with `flow=1`, then there will be a roughly 3:2:1
3500 ratio in how much one runs vs the others.
3502 .. option:: flow_sleep=int
3504 The period of time, in microseconds, to wait after the flow counter
3505 has exceeded its proportion before retrying operations.
3507 .. option:: stonewall, wait_for_previous
3509 Wait for preceding jobs in the job file to exit, before starting this
3510 one. Can be used to insert serialization points in the job file. A stone
3511 wall also implies starting a new reporting group, see
3512 :option:`group_reporting`.
3516 By default, fio will continue running all other jobs when one job finishes.
3517 Sometimes this is not the desired action. Setting ``exitall`` will instead
3518 make fio terminate all jobs in the same group, as soon as one job of that
3521 .. option:: exit_what=str
3523 By default, fio will continue running all other jobs when one job finishes.
3524 Sometimes this is not the desired action. Setting ``exitall`` will
3525 instead make fio terminate all jobs in the same group. The option
3526 ``exit_what`` allows to control which jobs get terminated when ``exitall`` is
3527 enabled. The default is ``group`` and does not change the behaviour of
3528 ``exitall``. The setting ``all`` terminates all jobs. The setting ``stonewall``
3529 terminates all currently running jobs across all groups and continues execution
3530 with the next stonewalled group.
3532 .. option:: exec_prerun=str
3534 Before running this job, issue the command specified through
3535 :manpage:`system(3)`. Output is redirected in a file called
3536 :file:`jobname.prerun.txt`.
3538 .. option:: exec_postrun=str
3540 After the job completes, issue the command specified though
3541 :manpage:`system(3)`. Output is redirected in a file called
3542 :file:`jobname.postrun.txt`.
3546 Instead of running as the invoking user, set the user ID to this value
3547 before the thread/process does any work.
3551 Set group ID, see :option:`uid`.
3557 .. option:: verify_only
3559 Do not perform specified workload, only verify data still matches previous
3560 invocation of this workload. This option allows one to check data multiple
3561 times at a later date without overwriting it. This option makes sense only
3562 for workloads that write data, and does not support workloads with the
3563 :option:`time_based` option set.
3565 .. option:: do_verify=bool
3567 Run the verify phase after a write phase. Only valid if :option:`verify` is
3570 .. option:: verify=str
3572 If writing to a file, fio can verify the file contents after each iteration
3573 of the job. Each verification method also implies verification of special
3574 header, which is written to the beginning of each block. This header also
3575 includes meta information, like offset of the block, block number, timestamp
3576 when block was written, etc. :option:`verify` can be combined with
3577 :option:`verify_pattern` option. The allowed values are:
3580 Use an md5 sum of the data area and store it in the header of
3584 Use an experimental crc64 sum of the data area and store it in the
3585 header of each block.
3588 Use a crc32c sum of the data area and store it in the header of
3589 each block. This will automatically use hardware acceleration
3590 (e.g. SSE4.2 on an x86 or CRC crypto extensions on ARM64) but will
3591 fall back to software crc32c if none is found. Generally the
3592 fastest checksum fio supports when hardware accelerated.
3598 Use a crc32 sum of the data area and store it in the header of each
3602 Use a crc16 sum of the data area and store it in the header of each
3606 Use a crc7 sum of the data area and store it in the header of each
3610 Use xxhash as the checksum function. Generally the fastest software
3611 checksum that fio supports.
3614 Use sha512 as the checksum function.
3617 Use sha256 as the checksum function.
3620 Use optimized sha1 as the checksum function.
3623 Use optimized sha3-224 as the checksum function.
3626 Use optimized sha3-256 as the checksum function.
3629 Use optimized sha3-384 as the checksum function.
3632 Use optimized sha3-512 as the checksum function.
3635 This option is deprecated, since now meta information is included in
3636 generic verification header and meta verification happens by
3637 default. For detailed information see the description of the
3638 :option:`verify` setting. This option is kept because of
3639 compatibility's sake with old configurations. Do not use it.
3642 Verify a strict pattern. Normally fio includes a header with some
3643 basic information and checksumming, but if this option is set, only
3644 the specific pattern set with :option:`verify_pattern` is verified.
3647 Only pretend to verify. Useful for testing internals with
3648 :option:`ioengine`\=null, not for much else.
3650 This option can be used for repeated burn-in tests of a system to make sure
3651 that the written data is also correctly read back. If the data direction
3652 given is a read or random read, fio will assume that it should verify a
3653 previously written file. If the data direction includes any form of write,
3654 the verify will be of the newly written data.
3656 To avoid false verification errors, do not use the norandommap option when
3657 verifying data with async I/O engines and I/O depths > 1. Or use the
3658 norandommap and the lfsr random generator together to avoid writing to the
3659 same offset with multiple outstanding I/Os.
3661 .. option:: verify_offset=int
3663 Swap the verification header with data somewhere else in the block before
3664 writing. It is swapped back before verifying.
3666 .. option:: verify_interval=int
3668 Write the verification header at a finer granularity than the
3669 :option:`blocksize`. It will be written for chunks the size of
3670 ``verify_interval``. :option:`blocksize` should divide this evenly.
3672 .. option:: verify_pattern=str
3674 If set, fio will fill the I/O buffers with this pattern. Fio defaults to
3675 filling with totally random bytes, but sometimes it's interesting to fill
3676 with a known pattern for I/O verification purposes. Depending on the width
3677 of the pattern, fio will fill 1/2/3/4 bytes of the buffer at the time (it can
3678 be either a decimal or a hex number). The ``verify_pattern`` if larger than
3679 a 32-bit quantity has to be a hex number that starts with either "0x" or
3680 "0X". Use with :option:`verify`. Also, ``verify_pattern`` supports %o
3681 format, which means that for each block offset will be written and then
3682 verified back, e.g.::
3686 Or use combination of everything::
3688 verify_pattern=0xff%o"abcd"-12
3690 .. option:: verify_fatal=bool
3692 Normally fio will keep checking the entire contents before quitting on a
3693 block verification failure. If this option is set, fio will exit the job on
3694 the first observed failure. Default: false.
3696 .. option:: verify_dump=bool
3698 If set, dump the contents of both the original data block and the data block
3699 we read off disk to files. This allows later analysis to inspect just what
3700 kind of data corruption occurred. Off by default.
3702 .. option:: verify_async=int
3704 Fio will normally verify I/O inline from the submitting thread. This option
3705 takes an integer describing how many async offload threads to create for I/O
3706 verification instead, causing fio to offload the duty of verifying I/O
3707 contents to one or more separate threads. If using this offload option, even
3708 sync I/O engines can benefit from using an :option:`iodepth` setting higher
3709 than 1, as it allows them to have I/O in flight while verifies are running.
3710 Defaults to 0 async threads, i.e. verification is not asynchronous.
3712 .. option:: verify_async_cpus=str
3714 Tell fio to set the given CPU affinity on the async I/O verification
3715 threads. See :option:`cpus_allowed` for the format used.
3717 .. option:: verify_backlog=int
3719 Fio will normally verify the written contents of a job that utilizes verify
3720 once that job has completed. In other words, everything is written then
3721 everything is read back and verified. You may want to verify continually
3722 instead for a variety of reasons. Fio stores the meta data associated with
3723 an I/O block in memory, so for large verify workloads, quite a bit of memory
3724 would be used up holding this meta data. If this option is enabled, fio will
3725 write only N blocks before verifying these blocks.
3727 .. option:: verify_backlog_batch=int
3729 Control how many blocks fio will verify if :option:`verify_backlog` is
3730 set. If not set, will default to the value of :option:`verify_backlog`
3731 (meaning the entire queue is read back and verified). If
3732 ``verify_backlog_batch`` is less than :option:`verify_backlog` then not all
3733 blocks will be verified, if ``verify_backlog_batch`` is larger than
3734 :option:`verify_backlog`, some blocks will be verified more than once.
3736 .. option:: verify_state_save=bool
3738 When a job exits during the write phase of a verify workload, save its
3739 current state. This allows fio to replay up until that point, if the verify
3740 state is loaded for the verify read phase. The format of the filename is,
3743 <type>-<jobname>-<jobindex>-verify.state.
3745 <type> is "local" for a local run, "sock" for a client/server socket
3746 connection, and "ip" (192.168.0.1, for instance) for a networked
3747 client/server connection. Defaults to true.
3749 .. option:: verify_state_load=bool
3751 If a verify termination trigger was used, fio stores the current write state
3752 of each thread. This can be used at verification time so that fio knows how
3753 far it should verify. Without this information, fio will run a full
3754 verification pass, according to the settings in the job file used. Default
3757 .. option:: trim_percentage=int
3759 Number of verify blocks to discard/trim.
3761 .. option:: trim_verify_zero=bool
3763 Verify that trim/discarded blocks are returned as zeros.
3765 .. option:: trim_backlog=int
3767 Trim after this number of blocks are written.
3769 .. option:: trim_backlog_batch=int
3771 Trim this number of I/O blocks.
3773 .. option:: experimental_verify=bool
3775 Enable experimental verification. Standard verify records I/O metadata
3776 for later use during the verification phase. Experimental verify
3777 instead resets the file after the write phase and then replays I/Os for
3778 the verification phase.
3783 .. option:: steadystate=str:float, ss=str:float
3785 Define the criterion and limit for assessing steady state performance. The
3786 first parameter designates the criterion whereas the second parameter sets
3787 the threshold. When the criterion falls below the threshold for the
3788 specified duration, the job will stop. For example, `iops_slope:0.1%` will
3789 direct fio to terminate the job when the least squares regression slope
3790 falls below 0.1% of the mean IOPS. If :option:`group_reporting` is enabled
3791 this will apply to all jobs in the group. Below is the list of available
3792 steady state assessment criteria. All assessments are carried out using only
3793 data from the rolling collection window. Threshold limits can be expressed
3794 as a fixed value or as a percentage of the mean in the collection window.
3796 When using this feature, most jobs should include the :option:`time_based`
3797 and :option:`runtime` options or the :option:`loops` option so that fio does not
3798 stop running after it has covered the full size of the specified file(s) or device(s).
3801 Collect IOPS data. Stop the job if all individual IOPS measurements
3802 are within the specified limit of the mean IOPS (e.g., ``iops:2``
3803 means that all individual IOPS values must be within 2 of the mean,
3804 whereas ``iops:0.2%`` means that all individual IOPS values must be
3805 within 0.2% of the mean IOPS to terminate the job).
3808 Collect IOPS data and calculate the least squares regression
3809 slope. Stop the job if the slope falls below the specified limit.
3812 Collect bandwidth data. Stop the job if all individual bandwidth
3813 measurements are within the specified limit of the mean bandwidth.
3816 Collect bandwidth data and calculate the least squares regression
3817 slope. Stop the job if the slope falls below the specified limit.
3819 .. option:: steadystate_duration=time, ss_dur=time
3821 A rolling window of this duration will be used to judge whether steady state
3822 has been reached. Data will be collected once per second. The default is 0
3823 which disables steady state detection. When the unit is omitted, the
3824 value is interpreted in seconds.
3826 .. option:: steadystate_ramp_time=time, ss_ramp=time
3828 Allow the job to run for the specified duration before beginning data
3829 collection for checking the steady state job termination criterion. The
3830 default is 0. When the unit is omitted, the value is interpreted in seconds.
3833 Measurements and reporting
3834 ~~~~~~~~~~~~~~~~~~~~~~~~~~
3836 .. option:: per_job_logs=bool
3838 If set, this generates bw/clat/iops log with per file private filenames. If
3839 not set, jobs with identical names will share the log filename. Default:
3842 .. option:: group_reporting
3844 It may sometimes be interesting to display statistics for groups of jobs as
3845 a whole instead of for each individual job. This is especially true if
3846 :option:`numjobs` is used; looking at individual thread/process output
3847 quickly becomes unwieldy. To see the final report per-group instead of
3848 per-job, use :option:`group_reporting`. Jobs in a file will be part of the
3849 same reporting group, unless if separated by a :option:`stonewall`, or by
3850 using :option:`new_group`.
3852 .. option:: new_group
3854 Start a new reporting group. See: :option:`group_reporting`. If not given,
3855 all jobs in a file will be part of the same reporting group, unless
3856 separated by a :option:`stonewall`.
3858 .. option:: stats=bool
3860 By default, fio collects and shows final output results for all jobs
3861 that run. If this option is set to 0, then fio will ignore it in
3862 the final stat output.
3864 .. option:: write_bw_log=str
3866 If given, write a bandwidth log for this job. Can be used to store data of
3867 the bandwidth of the jobs in their lifetime.
3869 If no str argument is given, the default filename of
3870 :file:`jobname_type.x.log` is used. Even when the argument is given, fio
3871 will still append the type of log. So if one specifies::
3875 The actual log name will be :file:`foo_bw.x.log` where `x` is the index
3876 of the job (`1..N`, where `N` is the number of jobs). If
3877 :option:`per_job_logs` is false, then the filename will not include the
3880 The included :command:`fio_generate_plots` script uses :command:`gnuplot` to turn these
3881 text files into nice graphs. See `Log File Formats`_ for how data is
3882 structured within the file.
3884 .. option:: write_lat_log=str
3886 Same as :option:`write_bw_log`, except this option creates I/O
3887 submission (e.g., :file:`name_slat.x.log`), completion (e.g.,
3888 :file:`name_clat.x.log`), and total (e.g., :file:`name_lat.x.log`)
3889 latency files instead. See :option:`write_bw_log` for details about
3890 the filename format and `Log File Formats`_ for how data is structured
3893 .. option:: write_hist_log=str
3895 Same as :option:`write_bw_log` but writes an I/O completion latency
3896 histogram file (e.g., :file:`name_hist.x.log`) instead. Note that this
3897 file will be empty unless :option:`log_hist_msec` has also been set.
3898 See :option:`write_bw_log` for details about the filename format and
3899 `Log File Formats`_ for how data is structured within the file.
3901 .. option:: write_iops_log=str
3903 Same as :option:`write_bw_log`, but writes an IOPS file (e.g.
3904 :file:`name_iops.x.log`) instead. Because fio defaults to individual
3905 I/O logging, the value entry in the IOPS log will be 1 unless windowed
3906 logging (see :option:`log_avg_msec`) has been enabled. See
3907 :option:`write_bw_log` for details about the filename format and `Log
3908 File Formats`_ for how data is structured within the file.
3910 .. option:: log_entries=int
3912 By default, fio will log an entry in the iops, latency, or bw log for
3913 every I/O that completes. The initial number of I/O log entries is 1024.
3914 When the log entries are all used, new log entries are dynamically
3915 allocated. This dynamic log entry allocation may negatively impact
3916 time-related statistics such as I/O tail latencies (e.g. 99.9th percentile
3917 completion latency). This option allows specifying a larger initial
3918 number of log entries to avoid run-time allocations of new log entries,
3919 resulting in more precise time-related I/O statistics.
3920 Also see :option:`log_avg_msec`. Defaults to 1024.
3922 .. option:: log_avg_msec=int
3924 By default, fio will log an entry in the iops, latency, or bw log for every
3925 I/O that completes. When writing to the disk log, that can quickly grow to a
3926 very large size. Setting this option makes fio average the each log entry
3927 over the specified period of time, reducing the resolution of the log. See
3928 :option:`log_max_value` as well. Defaults to 0, logging all entries.
3929 Also see `Log File Formats`_.
3931 .. option:: log_hist_msec=int
3933 Same as :option:`log_avg_msec`, but logs entries for completion latency
3934 histograms. Computing latency percentiles from averages of intervals using
3935 :option:`log_avg_msec` is inaccurate. Setting this option makes fio log
3936 histogram entries over the specified period of time, reducing log sizes for
3937 high IOPS devices while retaining percentile accuracy. See
3938 :option:`log_hist_coarseness` and :option:`write_hist_log` as well.
3939 Defaults to 0, meaning histogram logging is disabled.
3941 .. option:: log_hist_coarseness=int
3943 Integer ranging from 0 to 6, defining the coarseness of the resolution of
3944 the histogram logs enabled with :option:`log_hist_msec`. For each increment
3945 in coarseness, fio outputs half as many bins. Defaults to 0, for which
3946 histogram logs contain 1216 latency bins. See :option:`write_hist_log`
3947 and `Log File Formats`_.
3949 .. option:: log_max_value=bool
3951 If :option:`log_avg_msec` is set, fio logs the average over that window. If
3952 you instead want to log the maximum value, set this option to 1. Defaults to
3953 0, meaning that averaged values are logged.
3955 .. option:: log_offset=bool
3957 If this is set, the iolog options will include the byte offset for the I/O
3958 entry as well as the other data values. Defaults to 0 meaning that
3959 offsets are not present in logs. Also see `Log File Formats`_.
3961 .. option:: log_compression=int
3963 If this is set, fio will compress the I/O logs as it goes, to keep the
3964 memory footprint lower. When a log reaches the specified size, that chunk is
3965 removed and compressed in the background. Given that I/O logs are fairly
3966 highly compressible, this yields a nice memory savings for longer runs. The
3967 downside is that the compression will consume some background CPU cycles, so
3968 it may impact the run. This, however, is also true if the logging ends up
3969 consuming most of the system memory. So pick your poison. The I/O logs are
3970 saved normally at the end of a run, by decompressing the chunks and storing
3971 them in the specified log file. This feature depends on the availability of
3974 .. option:: log_compression_cpus=str
3976 Define the set of CPUs that are allowed to handle online log compression for
3977 the I/O jobs. This can provide better isolation between performance
3978 sensitive jobs, and background compression work. See
3979 :option:`cpus_allowed` for the format used.
3981 .. option:: log_store_compressed=bool
3983 If set, fio will store the log files in a compressed format. They can be
3984 decompressed with fio, using the :option:`--inflate-log` command line
3985 parameter. The files will be stored with a :file:`.fz` suffix.
3987 .. option:: log_unix_epoch=bool
3989 If set, fio will log Unix timestamps to the log files produced by enabling
3990 write_type_log for each log type, instead of the default zero-based
3993 .. option:: log_alternate_epoch=bool
3995 If set, fio will log timestamps based on the epoch used by the clock specified
3996 in the log_alternate_epoch_clock_id option, to the log files produced by
3997 enabling write_type_log for each log type, instead of the default zero-based
4000 .. option:: log_alternate_epoch_clock_id=int
4002 Specifies the clock_id to be used by clock_gettime to obtain the alternate epoch
4003 if either log_unix_epoch or log_alternate_epoch are true. Otherwise has no
4004 effect. Default value is 0, or CLOCK_REALTIME.
4006 .. option:: block_error_percentiles=bool
4008 If set, record errors in trim block-sized units from writes and trims and
4009 output a histogram of how many trims it took to get to errors, and what kind
4010 of error was encountered.
4012 .. option:: bwavgtime=int
4014 Average the calculated bandwidth over the given time. Value is specified in
4015 milliseconds. If the job also does bandwidth logging through
4016 :option:`write_bw_log`, then the minimum of this option and
4017 :option:`log_avg_msec` will be used. Default: 500ms.
4019 .. option:: iopsavgtime=int
4021 Average the calculated IOPS over the given time. Value is specified in
4022 milliseconds. If the job also does IOPS logging through
4023 :option:`write_iops_log`, then the minimum of this option and
4024 :option:`log_avg_msec` will be used. Default: 500ms.
4026 .. option:: disk_util=bool
4028 Generate disk utilization statistics, if the platform supports it.
4031 .. option:: disable_lat=bool
4033 Disable measurements of total latency numbers. Useful only for cutting back
4034 the number of calls to :manpage:`gettimeofday(2)`, as that does impact
4035 performance at really high IOPS rates. Note that to really get rid of a
4036 large amount of these calls, this option must be used with
4037 :option:`disable_slat` and :option:`disable_bw_measurement` as well.
4039 .. option:: disable_clat=bool
4041 Disable measurements of completion latency numbers. See
4042 :option:`disable_lat`.
4044 .. option:: disable_slat=bool
4046 Disable measurements of submission latency numbers. See
4047 :option:`disable_lat`.
4049 .. option:: disable_bw_measurement=bool, disable_bw=bool
4051 Disable measurements of throughput/bandwidth numbers. See
4052 :option:`disable_lat`.
4054 .. option:: slat_percentiles=bool
4056 Report submission latency percentiles. Submission latency is not recorded
4057 for synchronous ioengines.
4059 .. option:: clat_percentiles=bool
4061 Report completion latency percentiles.
4063 .. option:: lat_percentiles=bool
4065 Report total latency percentiles. Total latency is the sum of submission
4066 latency and completion latency.
4068 .. option:: percentile_list=float_list
4070 Overwrite the default list of percentiles for latencies and the block error
4071 histogram. Each number is a floating point number in the range (0,100], and
4072 the maximum length of the list is 20. Use ``:`` to separate the numbers. For
4073 example, ``--percentile_list=99.5:99.9`` will cause fio to report the
4074 latency durations below which 99.5% and 99.9% of the observed latencies fell,
4077 .. option:: significant_figures=int
4079 If using :option:`--output-format` of `normal`, set the significant
4080 figures to this value. Higher values will yield more precise IOPS and
4081 throughput units, while lower values will round. Requires a minimum
4082 value of 1 and a maximum value of 10. Defaults to 4.
4088 .. option:: exitall_on_error
4090 When one job finishes in error, terminate the rest. The default is to wait
4091 for each job to finish.
4093 .. option:: continue_on_error=str
4095 Normally fio will exit the job on the first observed failure. If this option
4096 is set, fio will continue the job when there is a 'non-fatal error' (EIO or
4097 EILSEQ) until the runtime is exceeded or the I/O size specified is
4098 completed. If this option is used, there are two more stats that are
4099 appended, the total error count and the first error. The error field given
4100 in the stats is the first error that was hit during the run.
4102 Note: a write error from the device may go unnoticed by fio when using
4103 buffered IO, as the write() (or similar) system call merely dirties the
4104 kernel pages, unless :option:`sync` or :option:`direct` is used. Device IO
4105 errors occur when the dirty data is actually written out to disk. If fully
4106 sync writes aren't desirable, :option:`fsync` or :option:`fdatasync` can be
4107 used as well. This is specific to writes, as reads are always synchronous.
4109 The allowed values are:
4112 Exit on any I/O or verify errors.
4115 Continue on read errors, exit on all others.
4118 Continue on write errors, exit on all others.
4121 Continue on any I/O error, exit on all others.
4124 Continue on verify errors, exit on all others.
4127 Continue on all errors.
4130 Backward-compatible alias for 'none'.
4133 Backward-compatible alias for 'all'.
4135 .. option:: ignore_error=str
4137 Sometimes you want to ignore some errors during test in that case you can
4138 specify error list for each error type, instead of only being able to
4139 ignore the default 'non-fatal error' using :option:`continue_on_error`.
4140 ``ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST`` errors for
4141 given error type is separated with ':'. Error may be symbol ('ENOSPC',
4142 'ENOMEM') or integer. Example::
4144 ignore_error=EAGAIN,ENOSPC:122
4146 This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from
4147 WRITE. This option works by overriding :option:`continue_on_error` with
4148 the list of errors for each error type if any.
4150 .. option:: error_dump=bool
4152 If set dump every error even if it is non fatal, true by default. If
4153 disabled only fatal error will be dumped.
4155 Running predefined workloads
4156 ----------------------------
4158 Fio includes predefined profiles that mimic the I/O workloads generated by
4161 .. option:: profile=str
4163 The predefined workload to run. Current profiles are:
4166 Threaded I/O bench (tiotest/tiobench) like workload.
4169 Aerospike Certification Tool (ACT) like workload.
4171 To view a profile's additional options use :option:`--cmdhelp` after specifying
4172 the profile. For example::
4174 $ fio --profile=act --cmdhelp
4179 .. option:: device-names=str
4184 .. option:: load=int
4187 ACT load multiplier. Default: 1.
4189 .. option:: test-duration=time
4192 How long the entire test takes to run. When the unit is omitted, the value
4193 is given in seconds. Default: 24h.
4195 .. option:: threads-per-queue=int
4198 Number of read I/O threads per device. Default: 8.
4200 .. option:: read-req-num-512-blocks=int
4203 Number of 512B blocks to read at the time. Default: 3.
4205 .. option:: large-block-op-kbytes=int
4208 Size of large block ops in KiB (writes). Default: 131072.
4213 Set to run ACT prep phase.
4215 Tiobench profile options
4216 ~~~~~~~~~~~~~~~~~~~~~~~~
4218 .. option:: size=str
4223 .. option:: block=int
4226 Block size in bytes. Default: 4096.
4228 .. option:: numruns=int
4238 .. option:: threads=int
4243 Interpreting the output
4244 -----------------------
4247 Example output was based on the following:
4248 TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --time_based \
4249 --rate=1256k --bs=14K --name=quick --runtime=1s --name=mixed \
4250 --runtime=2m --rw=rw
4252 Fio spits out a lot of output. While running, fio will display the status of the
4253 jobs created. An example of that would be::
4255 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]
4257 The characters inside the first set of square brackets denote the current status of
4258 each thread. The first character is the first job defined in the job file, and so
4259 forth. The possible values (in typical life cycle order) are:
4261 +------+-----+-----------------------------------------------------------+
4263 +======+=====+===========================================================+
4264 | P | | Thread setup, but not started. |
4265 +------+-----+-----------------------------------------------------------+
4266 | C | | Thread created. |
4267 +------+-----+-----------------------------------------------------------+
4268 | I | | Thread initialized, waiting or generating necessary data. |
4269 +------+-----+-----------------------------------------------------------+
4270 | | p | Thread running pre-reading file(s). |
4271 +------+-----+-----------------------------------------------------------+
4272 | | / | Thread is in ramp period. |
4273 +------+-----+-----------------------------------------------------------+
4274 | | R | Running, doing sequential reads. |
4275 +------+-----+-----------------------------------------------------------+
4276 | | r | Running, doing random reads. |
4277 +------+-----+-----------------------------------------------------------+
4278 | | W | Running, doing sequential writes. |
4279 +------+-----+-----------------------------------------------------------+
4280 | | w | Running, doing random writes. |
4281 +------+-----+-----------------------------------------------------------+
4282 | | M | Running, doing mixed sequential reads/writes. |
4283 +------+-----+-----------------------------------------------------------+
4284 | | m | Running, doing mixed random reads/writes. |
4285 +------+-----+-----------------------------------------------------------+
4286 | | D | Running, doing sequential trims. |
4287 +------+-----+-----------------------------------------------------------+
4288 | | d | Running, doing random trims. |
4289 +------+-----+-----------------------------------------------------------+
4290 | | F | Running, currently waiting for :manpage:`fsync(2)`. |
4291 +------+-----+-----------------------------------------------------------+
4292 | | V | Running, doing verification of written data. |
4293 +------+-----+-----------------------------------------------------------+
4294 | f | | Thread finishing. |
4295 +------+-----+-----------------------------------------------------------+
4296 | E | | Thread exited, not reaped by main thread yet. |
4297 +------+-----+-----------------------------------------------------------+
4298 | _ | | Thread reaped. |
4299 +------+-----+-----------------------------------------------------------+
4300 | X | | Thread reaped, exited with an error. |
4301 +------+-----+-----------------------------------------------------------+
4302 | K | | Thread reaped, exited due to signal. |
4303 +------+-----+-----------------------------------------------------------+
4306 Example output was based on the following:
4307 TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --runtime=58m \
4308 --time_based --rate=2512k --bs=256K --numjobs=10 \
4309 --name=readers --rw=read --name=writers --rw=write
4311 Fio will condense the thread string as not to take up more space on the command
4312 line than needed. For instance, if you have 10 readers and 10 writers running,
4313 the output would look like this::
4315 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]
4317 Note that the status string is displayed in order, so it's possible to tell which of
4318 the jobs are currently doing what. In the example above this means that jobs 1--10
4319 are readers and 11--20 are writers.
4321 The other values are fairly self explanatory -- number of threads currently
4322 running and doing I/O, the number of currently open files (f=), the estimated
4323 completion percentage, the rate of I/O since last check (read speed listed first,
4324 then write speed and optionally trim speed) in terms of bandwidth and IOPS,
4325 and time to completion for the current running group. It's impossible to estimate
4326 runtime of the following groups (if any).
4329 Example output was based on the following:
4330 TZ=UTC fio --iodepth=16 --ioengine=posixaio --filename=/tmp/fiofile \
4331 --direct=1 --size=100M --time_based --runtime=50s --rate_iops=89 \
4332 --bs=7K --name=Client1 --rw=write
4334 When fio is done (or interrupted by :kbd:`Ctrl-C`), it will show the data for
4335 each thread, group of threads, and disks in that order. For each overall thread (or
4336 group) the output looks like::
4338 Client1: (groupid=0, jobs=1): err= 0: pid=16109: Sat Jun 24 12:07:54 2017
4339 write: IOPS=88, BW=623KiB/s (638kB/s)(30.4MiB/50032msec)
4340 slat (nsec): min=500, max=145500, avg=8318.00, stdev=4781.50
4341 clat (usec): min=170, max=78367, avg=4019.02, stdev=8293.31
4342 lat (usec): min=174, max=78375, avg=4027.34, stdev=8291.79
4343 clat percentiles (usec):
4344 | 1.00th=[ 302], 5.00th=[ 326], 10.00th=[ 343], 20.00th=[ 363],
4345 | 30.00th=[ 392], 40.00th=[ 404], 50.00th=[ 416], 60.00th=[ 445],
4346 | 70.00th=[ 816], 80.00th=[ 6718], 90.00th=[12911], 95.00th=[21627],
4347 | 99.00th=[43779], 99.50th=[51643], 99.90th=[68682], 99.95th=[72877],
4349 bw ( KiB/s): min= 532, max= 686, per=0.10%, avg=622.87, stdev=24.82, samples= 100
4350 iops : min= 76, max= 98, avg=88.98, stdev= 3.54, samples= 100
4351 lat (usec) : 250=0.04%, 500=64.11%, 750=4.81%, 1000=2.79%
4352 lat (msec) : 2=4.16%, 4=1.84%, 10=4.90%, 20=11.33%, 50=5.37%
4353 lat (msec) : 100=0.65%
4354 cpu : usr=0.27%, sys=0.18%, ctx=12072, majf=0, minf=21
4355 IO depths : 1=85.0%, 2=13.1%, 4=1.8%, 8=0.1%, 16=0.0%, 32=0.0%, >=64=0.0%
4356 submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
4357 complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
4358 issued rwt: total=0,4450,0, short=0,0,0, dropped=0,0,0
4359 latency : target=0, window=0, percentile=100.00%, depth=8
4361 The job name (or first job's name when using :option:`group_reporting`) is printed,
4362 along with the group id, count of jobs being aggregated, last error id seen (which
4363 is 0 when there are no errors), pid/tid of that thread and the time the job/group
4364 completed. Below are the I/O statistics for each data direction performed (showing
4365 writes in the example above). In the order listed, they denote:
4368 The string before the colon shows the I/O direction the statistics
4369 are for. **IOPS** is the average I/Os performed per second. **BW**
4370 is the average bandwidth rate shown as: value in power of 2 format
4371 (value in power of 10 format). The last two values show: (**total
4372 I/O performed** in power of 2 format / **runtime** of that thread).
4375 Submission latency (**min** being the minimum, **max** being the
4376 maximum, **avg** being the average, **stdev** being the standard
4377 deviation). This is the time from when fio initialized the I/O
4378 to submission. For synchronous ioengines this includes the time
4379 up until just before the ioengine's queue function is called.
4380 For asynchronous ioengines this includes the time up through the
4381 completion of the ioengine's queue function (and commit function
4382 if it is defined). For sync I/O this row is not displayed as the
4383 slat is negligible. This value can be in nanoseconds,
4384 microseconds or milliseconds --- fio will choose the most
4385 appropriate base and print that (in the example above
4386 nanoseconds was the best scale). Note: in :option:`--minimal`
4387 mode latencies are always expressed in microseconds.
4390 Completion latency. Same names as slat, this denotes the time from
4391 submission to completion of the I/O pieces. For sync I/O, this
4392 represents the time from when the I/O was submitted to the
4393 operating system to when it was completed. For asynchronous
4394 ioengines this is the time from when the ioengine's queue (and
4395 commit if available) functions were completed to when the I/O's
4396 completion was reaped by fio.
4399 Total latency. Same names as slat and clat, this denotes the time from
4400 when fio created the I/O unit to completion of the I/O operation.
4401 It is the sum of submission and completion latency.
4404 Bandwidth statistics based on samples. Same names as the xlat stats,
4405 but also includes the number of samples taken (**samples**) and an
4406 approximate percentage of total aggregate bandwidth this thread
4407 received in its group (**per**). This last value is only really
4408 useful if the threads in this group are on the same disk, since they
4409 are then competing for disk access.
4412 IOPS statistics based on samples. Same names as bw.
4414 **lat (nsec/usec/msec)**
4415 The distribution of I/O completion latencies. This is the time from when
4416 I/O leaves fio and when it gets completed. Unlike the separate
4417 read/write/trim sections above, the data here and in the remaining
4418 sections apply to all I/Os for the reporting group. 250=0.04% means that
4419 0.04% of the I/Os completed in under 250us. 500=64.11% means that 64.11%
4420 of the I/Os required 250 to 499us for completion.
4423 CPU usage. User and system time, along with the number of context
4424 switches this thread went through, usage of system and user time, and
4425 finally the number of major and minor page faults. The CPU utilization
4426 numbers are averages for the jobs in that reporting group, while the
4427 context and fault counters are summed.
4430 The distribution of I/O depths over the job lifetime. The numbers are
4431 divided into powers of 2 and each entry covers depths from that value
4432 up to those that are lower than the next entry -- e.g., 16= covers
4433 depths from 16 to 31. Note that the range covered by a depth
4434 distribution entry can be different to the range covered by the
4435 equivalent submit/complete distribution entry.
4438 How many pieces of I/O were submitting in a single submit call. Each
4439 entry denotes that amount and below, until the previous entry -- e.g.,
4440 16=100% means that we submitted anywhere between 9 to 16 I/Os per submit
4441 call. Note that the range covered by a submit distribution entry can
4442 be different to the range covered by the equivalent depth distribution
4446 Like the above submit number, but for completions instead.
4449 The number of read/write/trim requests issued, and how many of them were
4453 These values are for :option:`latency_target` and related options. When
4454 these options are engaged, this section describes the I/O depth required
4455 to meet the specified latency target.
4458 Example output was based on the following:
4459 TZ=UTC fio --ioengine=null --iodepth=2 --size=100M --numjobs=2 \
4460 --rate_process=poisson --io_limit=32M --name=read --bs=128k \
4461 --rate=11M --name=write --rw=write --bs=2k --rate=700k
4463 After each client has been listed, the group statistics are printed. They
4464 will look like this::
4466 Run status group 0 (all jobs):
4467 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
4468 WRITE: bw=1231KiB/s (1261kB/s), 616KiB/s-621KiB/s (630kB/s-636kB/s), io=64.0MiB (67.1MB), run=52747-53223msec
4470 For each data direction it prints:
4473 Aggregate bandwidth of threads in this group followed by the
4474 minimum and maximum bandwidth of all the threads in this group.
4475 Values outside of brackets are power-of-2 format and those
4476 within are the equivalent value in a power-of-10 format.
4478 Aggregate I/O performed of all threads in this group. The
4479 format is the same as bw.
4481 The smallest and longest runtimes of the threads in this group.
4483 And finally, the disk statistics are printed. This is Linux specific. They will look like this::
4485 Disk stats (read/write):
4486 sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00%
4488 Each value is printed for both reads and writes, with reads first. The
4492 Number of I/Os performed by all groups.
4494 Number of merges performed by the I/O scheduler.
4496 Number of ticks we kept the disk busy.
4498 Total time spent in the disk queue.
4500 The disk utilization. A value of 100% means we kept the disk
4501 busy constantly, 50% would be a disk idling half of the time.
4503 It is also possible to get fio to dump the current output while it is running,
4504 without terminating the job. To do that, send fio the **USR1** signal. You can
4505 also get regularly timed dumps by using the :option:`--status-interval`
4506 parameter, or by creating a file in :file:`/tmp` named
4507 :file:`fio-dump-status`. If fio sees this file, it will unlink it and dump the
4508 current output status.
4514 For scripted usage where you typically want to generate tables or graphs of the
4515 results, fio can output the results in a semicolon separated format. The format
4516 is one long line of values, such as::
4518 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%
4519 A description of this job goes here.
4521 The job description (if provided) follows on a second line for terse v2.
4522 It appears on the same line for other terse versions.
4524 To enable terse output, use the :option:`--minimal` or
4525 :option:`--output-format`\=terse command line options. The
4526 first value is the version of the terse output format. If the output has to be
4527 changed for some reason, this number will be incremented by 1 to signify that
4530 Split up, the format is as follows (comments in brackets denote when a
4531 field was introduced or whether it's specific to some terse version):
4535 terse version, fio version [v3], jobname, groupid, error
4539 Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
4540 Submission latency: min, max, mean, stdev (usec)
4541 Completion latency: min, max, mean, stdev (usec)
4542 Completion latency percentiles: 20 fields (see below)
4543 Total latency: min, max, mean, stdev (usec)
4544 Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
4545 IOPS [v5]: min, max, mean, stdev, number of samples
4551 Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
4552 Submission latency: min, max, mean, stdev (usec)
4553 Completion latency: min, max, mean, stdev (usec)
4554 Completion latency percentiles: 20 fields (see below)
4555 Total latency: min, max, mean, stdev (usec)
4556 Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
4557 IOPS [v5]: min, max, mean, stdev, number of samples
4559 TRIM status [all but version 3]:
4561 Fields are similar to READ/WRITE status.
4565 user, system, context switches, major faults, minor faults
4569 <=1, 2, 4, 8, 16, 32, >=64
4571 I/O latencies microseconds::
4573 <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
4575 I/O latencies milliseconds::
4577 <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
4579 Disk utilization [v3]::
4581 disk name, read ios, write ios, read merges, write merges, read ticks, write ticks,
4582 time spent in queue, disk utilization percentage
4584 Additional Info (dependent on continue_on_error, default off)::
4586 total # errors, first error code
4588 Additional Info (dependent on description being set)::
4592 Completion latency percentiles can be a grouping of up to 20 sets, so for the
4593 terse output fio writes all of them. Each field will look like this::
4597 which is the Xth percentile, and the `usec` latency associated with it.
4599 For `Disk utilization`, all disks used by fio are shown. So for each disk there
4600 will be a disk utilization section.
4602 Below is a single line containing short names for each of the fields in the
4603 minimal output v3, separated by semicolons::
4605 terse_version_3;fio_version;jobname;groupid;error;read_kb;read_bandwidth_kb;read_iops;read_runtime_ms;read_slat_min_us;read_slat_max_us;read_slat_mean_us;read_slat_dev_us;read_clat_min_us;read_clat_max_us;read_clat_mean_us;read_clat_dev_us;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_us;read_lat_max_us;read_lat_mean_us;read_lat_dev_us;read_bw_min_kb;read_bw_max_kb;read_bw_agg_pct;read_bw_mean_kb;read_bw_dev_kb;write_kb;write_bandwidth_kb;write_iops;write_runtime_ms;write_slat_min_us;write_slat_max_us;write_slat_mean_us;write_slat_dev_us;write_clat_min_us;write_clat_max_us;write_clat_mean_us;write_clat_dev_us;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_us;write_lat_max_us;write_lat_mean_us;write_lat_dev_us;write_bw_min_kb;write_bw_max_kb;write_bw_agg_pct;write_bw_mean_kb;write_bw_dev_kb;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
4607 In client/server mode terse output differs from what appears when jobs are run
4608 locally. Disk utilization data is omitted from the standard terse output and
4609 for v3 and later appears on its own separate line at the end of each terse
4616 The `json` output format is intended to be both human readable and convenient
4617 for automated parsing. For the most part its sections mirror those of the
4618 `normal` output. The `runtime` value is reported in msec and the `bw` value is
4619 reported in 1024 bytes per second units.
4625 The `json+` output format is identical to the `json` output format except that it
4626 adds a full dump of the completion latency bins. Each `bins` object contains a
4627 set of (key, value) pairs where keys are latency durations and values count how
4628 many I/Os had completion latencies of the corresponding duration. For example,
4631 "bins" : { "87552" : 1, "89600" : 1, "94720" : 1, "96768" : 1, "97792" : 1, "99840" : 1, "100864" : 2, "103936" : 6, "104960" : 534, "105984" : 5995, "107008" : 7529, ... }
4633 This data indicates that one I/O required 87,552ns to complete, two I/Os required
4634 100,864ns to complete, and 7529 I/Os required 107,008ns to complete.
4636 Also included with fio is a Python script `fio_jsonplus_clat2csv` that takes
4637 json+ output and generates CSV-formatted latency data suitable for plotting.
4639 The latency durations actually represent the midpoints of latency intervals.
4640 For details refer to :file:`stat.h`.
4646 There are two trace file format that you can encounter. The older (v1) format is
4647 unsupported since version 1.20-rc3 (March 2008). It will still be described
4648 below in case that you get an old trace and want to understand it.
4650 In any case the trace is a simple text file with a single action per line.
4653 Trace file format v1
4654 ~~~~~~~~~~~~~~~~~~~~
4656 Each line represents a single I/O action in the following format::
4660 where `rw=0/1` for read/write, and the `offset` and `length` entries being in bytes.
4662 This format is not supported in fio versions >= 1.20-rc3.
4665 Trace file format v2
4666 ~~~~~~~~~~~~~~~~~~~~
4668 The second version of the trace file format was added in fio version 1.17. It
4669 allows one to access more than one file per trace and has a bigger set of possible
4672 The first line of the trace file has to be::
4676 Following this can be lines in two different formats, which are described below.
4678 The file management format::
4682 The `filename` is given as an absolute path. The `action` can be one of these:
4685 Add the given `filename` to the trace.
4687 Open the file with the given `filename`. The `filename` has to have
4688 been added with the **add** action before.
4690 Close the file with the given `filename`. The file has to have been
4694 The file I/O action format::
4696 filename action offset length
4698 The `filename` is given as an absolute path, and has to have been added and
4699 opened before it can be used with this format. The `offset` and `length` are
4700 given in bytes. The `action` can be one of these:
4703 Wait for `offset` microseconds. Everything below 100 is discarded.
4704 The time is relative to the previous `wait` statement. Note that
4705 action `wait` is not allowed as of version 3, as the same behavior
4706 can be achieved using timestamps.
4708 Read `length` bytes beginning from `offset`.
4710 Write `length` bytes beginning from `offset`.
4712 :manpage:`fsync(2)` the file.
4714 :manpage:`fdatasync(2)` the file.
4716 Trim the given file from the given `offset` for `length` bytes.
4719 Trace file format v3
4720 ~~~~~~~~~~~~~~~~~~~~
4722 The third version of the trace file format was added in fio version 3.31. It
4723 forces each action to have a timestamp associated with it.
4725 The first line of the trace file has to be::
4729 Following this can be lines in two different formats, which are described below.
4731 The file management format::
4733 timestamp filename action
4735 The file I/O action format::
4737 timestamp filename action offset length
4739 The `timestamp` is relative to the beginning of the run (ie starts at 0). The
4740 `filename`, `action`, `offset` and `length` are identical to version 2, except
4741 that version 3 does not allow the `wait` action.
4744 I/O Replay - Merging Traces
4745 ---------------------------
4747 Colocation is a common practice used to get the most out of a machine.
4748 Knowing which workloads play nicely with each other and which ones don't is
4749 a much harder task. While fio can replay workloads concurrently via multiple
4750 jobs, it leaves some variability up to the scheduler making results harder to
4751 reproduce. Merging is a way to make the order of events consistent.
4753 Merging is integrated into I/O replay and done when a
4754 :option:`merge_blktrace_file` is specified. The list of files passed to
4755 :option:`read_iolog` go through the merge process and output a single file
4756 stored to the specified file. The output file is passed on as if it were the
4757 only file passed to :option:`read_iolog`. An example would look like::
4759 $ fio --read_iolog="<file1>:<file2>" --merge_blktrace_file="<output_file>"
4761 Creating only the merged file can be done by passing the command line argument
4762 :option:`--merge-blktrace-only`.
4764 Scaling traces can be done to see the relative impact of any particular trace
4765 being slowed down or sped up. :option:`merge_blktrace_scalars` takes in a colon
4766 separated list of percentage scalars. It is index paired with the files passed
4767 to :option:`read_iolog`.
4769 With scaling, it may be desirable to match the running time of all traces.
4770 This can be done with :option:`merge_blktrace_iters`. It is index paired with
4771 :option:`read_iolog` just like :option:`merge_blktrace_scalars`.
4773 In an example, given two traces, A and B, each 60s long. If we want to see
4774 the impact of trace A issuing IOs twice as fast and repeat trace A over the
4775 runtime of trace B, the following can be done::
4777 $ fio --read_iolog="<trace_a>:"<trace_b>" --merge_blktrace_file"<output_file>" --merge_blktrace_scalars="50:100" --merge_blktrace_iters="2:1"
4779 This runs trace A at 2x the speed twice for approximately the same runtime as
4780 a single run of trace B.
4783 CPU idleness profiling
4784 ----------------------
4786 In some cases, we want to understand CPU overhead in a test. For example, we
4787 test patches for the specific goodness of whether they reduce CPU usage.
4788 Fio implements a balloon approach to create a thread per CPU that runs at idle
4789 priority, meaning that it only runs when nobody else needs the cpu.
4790 By measuring the amount of work completed by the thread, idleness of each CPU
4791 can be derived accordingly.
4793 An unit work is defined as touching a full page of unsigned characters. Mean and
4794 standard deviation of time to complete an unit work is reported in "unit work"
4795 section. Options can be chosen to report detailed percpu idleness or overall
4796 system idleness by aggregating percpu stats.
4799 Verification and triggers
4800 -------------------------
4802 Fio is usually run in one of two ways, when data verification is done. The first
4803 is a normal write job of some sort with verify enabled. When the write phase has
4804 completed, fio switches to reads and verifies everything it wrote. The second
4805 model is running just the write phase, and then later on running the same job
4806 (but with reads instead of writes) to repeat the same I/O patterns and verify
4807 the contents. Both of these methods depend on the write phase being completed,
4808 as fio otherwise has no idea how much data was written.
4810 With verification triggers, fio supports dumping the current write state to
4811 local files. Then a subsequent read verify workload can load this state and know
4812 exactly where to stop. This is useful for testing cases where power is cut to a
4813 server in a managed fashion, for instance.
4815 A verification trigger consists of two things:
4817 1) Storing the write state of each job.
4818 2) Executing a trigger command.
4820 The write state is relatively small, on the order of hundreds of bytes to single
4821 kilobytes. It contains information on the number of completions done, the last X
4824 A trigger is invoked either through creation ('touch') of a specified file in
4825 the system, or through a timeout setting. If fio is run with
4826 :option:`--trigger-file`\= :file:`/tmp/trigger-file`, then it will continually
4827 check for the existence of :file:`/tmp/trigger-file`. When it sees this file, it
4828 will fire off the trigger (thus saving state, and executing the trigger
4831 For client/server runs, there's both a local and remote trigger. If fio is
4832 running as a server backend, it will send the job states back to the client for
4833 safe storage, then execute the remote trigger, if specified. If a local trigger
4834 is specified, the server will still send back the write state, but the client
4835 will then execute the trigger.
4837 Verification trigger example
4838 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
4840 Let's say we want to run a powercut test on the remote Linux machine 'server'.
4841 Our write workload is in :file:`write-test.fio`. We want to cut power to 'server' at
4842 some point during the run, and we'll run this test from the safety or our local
4843 machine, 'localbox'. On the server, we'll start the fio backend normally::
4845 server# fio --server
4847 and on the client, we'll fire off the workload::
4849 localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger-remote="bash -c \"echo b > /proc/sysrq-triger\""
4851 We set :file:`/tmp/my-trigger` as the trigger file, and we tell fio to execute::
4853 echo b > /proc/sysrq-trigger
4855 on the server once it has received the trigger and sent us the write state. This
4856 will work, but it's not **really** cutting power to the server, it's merely
4857 abruptly rebooting it. If we have a remote way of cutting power to the server
4858 through IPMI or similar, we could do that through a local trigger command
4859 instead. Let's assume we have a script that does IPMI reboot of a given hostname,
4860 ipmi-reboot. On localbox, we could then have run fio with a local trigger
4863 localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger="ipmi-reboot server"
4865 For this case, fio would wait for the server to send us the write state, then
4866 execute ``ipmi-reboot server`` when that happened.
4868 Loading verify state
4869 ~~~~~~~~~~~~~~~~~~~~
4871 To load stored write state, a read verification job file must contain the
4872 :option:`verify_state_load` option. If that is set, fio will load the previously
4873 stored state. For a local fio run this is done by loading the files directly,
4874 and on a client/server run, the server backend will ask the client to send the
4875 files over and load them from there.
4881 Fio supports a variety of log file formats, for logging latencies, bandwidth,
4882 and IOPS. The logs share a common format, which looks like this:
4884 *time* (`msec`), *value*, *data direction*, *block size* (`bytes`),
4885 *offset* (`bytes`), *command priority*
4887 *Time* for the log entry is always in milliseconds. The *value* logged depends
4888 on the type of log, it will be one of the following:
4891 Value is latency in nsecs
4897 *Data direction* is one of the following:
4906 The entry's *block size* is always in bytes. The *offset* is the position in bytes
4907 from the start of the file for that particular I/O. The logging of the offset can be
4908 toggled with :option:`log_offset`.
4910 *Command priority* is 0 for normal priority and 1 for high priority. This is controlled
4911 by the ioengine specific :option:`cmdprio_percentage`.
4913 Fio defaults to logging every individual I/O but when windowed logging is set
4914 through :option:`log_avg_msec`, either the average (by default) or the maximum
4915 (:option:`log_max_value` is set) *value* seen over the specified period of time
4916 is recorded. Each *data direction* seen within the window period will aggregate
4917 its values in a separate row. Further, when using windowed logging the *block
4918 size* and *offset* entries will always contain 0.
4924 Normally fio is invoked as a stand-alone application on the machine where the
4925 I/O workload should be generated. However, the backend and frontend of fio can
4926 be run separately i.e., the fio server can generate an I/O workload on the "Device
4927 Under Test" while being controlled by a client on another machine.
4929 Start the server on the machine which has access to the storage DUT::
4933 where `args` defines what fio listens to. The arguments are of the form
4934 ``type,hostname`` or ``IP,port``. *type* is either ``ip`` (or ip4) for TCP/IP
4935 v4, ``ip6`` for TCP/IP v6, or ``sock`` for a local unix domain socket.
4936 *hostname* is either a hostname or IP address, and *port* is the port to listen
4937 to (only valid for TCP/IP, not a local socket). Some examples:
4941 Start a fio server, listening on all interfaces on the default port (8765).
4943 2) ``fio --server=ip:hostname,4444``
4945 Start a fio server, listening on IP belonging to hostname and on port 4444.
4947 3) ``fio --server=ip6:::1,4444``
4949 Start a fio server, listening on IPv6 localhost ::1 and on port 4444.
4951 4) ``fio --server=,4444``
4953 Start a fio server, listening on all interfaces on port 4444.
4955 5) ``fio --server=1.2.3.4``
4957 Start a fio server, listening on IP 1.2.3.4 on the default port.
4959 6) ``fio --server=sock:/tmp/fio.sock``
4961 Start a fio server, listening on the local socket :file:`/tmp/fio.sock`.
4963 Once a server is running, a "client" can connect to the fio server with::
4965 fio <local-args> --client=<server> <remote-args> <job file(s)>
4967 where `local-args` are arguments for the client where it is running, `server`
4968 is the connect string, and `remote-args` and `job file(s)` are sent to the
4969 server. The `server` string follows the same format as it does on the server
4970 side, to allow IP/hostname/socket and port strings.
4972 Fio can connect to multiple servers this way::
4974 fio --client=<server1> <job file(s)> --client=<server2> <job file(s)>
4976 If the job file is located on the fio server, then you can tell the server to
4977 load a local file as well. This is done by using :option:`--remote-config` ::
4979 fio --client=server --remote-config /path/to/file.fio
4981 Then fio will open this local (to the server) job file instead of being passed
4982 one from the client.
4984 If you have many servers (example: 100 VMs/containers), you can input a pathname
4985 of a file containing host IPs/names as the parameter value for the
4986 :option:`--client` option. For example, here is an example :file:`host.list`
4987 file containing 2 hostnames::
4989 host1.your.dns.domain
4990 host2.your.dns.domain
4992 The fio command would then be::
4994 fio --client=host.list <job file(s)>
4996 In this mode, you cannot input server-specific parameters or job files -- all
4997 servers receive the same job file.
4999 In order to let ``fio --client`` runs use a shared filesystem from multiple
5000 hosts, ``fio --client`` now prepends the IP address of the server to the
5001 filename. For example, if fio is using the directory :file:`/mnt/nfs/fio` and is
5002 writing filename :file:`fileio.tmp`, with a :option:`--client` `hostfile`
5003 containing two hostnames ``h1`` and ``h2`` with IP addresses 192.168.10.120 and
5004 192.168.10.121, then fio will create two files::
5006 /mnt/nfs/fio/192.168.10.120.fileio.tmp
5007 /mnt/nfs/fio/192.168.10.121.fileio.tmp
5009 Terse output in client/server mode will differ slightly from what is produced
5010 when fio is run in stand-alone mode. See the terse output section for details.