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:: buffered=bool
1115 If value is true, use buffered I/O. This is the opposite of the
1116 :option:`direct` option. Defaults to true.
1118 .. option:: readwrite=str, rw=str
1120 Type of I/O pattern. Accepted values are:
1127 Sequential trims (Linux block devices and SCSI
1128 character devices only).
1134 Random trims (Linux block devices and SCSI
1135 character devices only).
1137 Sequential mixed reads and writes.
1139 Random mixed reads and writes.
1141 Sequential trim+write sequences. Blocks will be trimmed first,
1142 then the same blocks will be written to. So if ``io_size=64K``
1143 is specified, Fio will trim a total of 64K bytes and also
1144 write 64K bytes on the same trimmed blocks. This behaviour
1145 will be consistent with ``number_ios`` or other Fio options
1146 limiting the total bytes or number of I/O's.
1148 Like trimwrite, but uses random offsets rather
1149 than sequential writes.
1151 Fio defaults to read if the option is not specified. For the mixed I/O
1152 types, the default is to split them 50/50. For certain types of I/O the
1153 result may still be skewed a bit, since the speed may be different.
1155 It is possible to specify the number of I/Os to do before getting a new
1156 offset by appending ``:<nr>`` to the end of the string given. For a
1157 random read, it would look like ``rw=randread:8`` for passing in an offset
1158 modifier with a value of 8. If the suffix is used with a sequential I/O
1159 pattern, then the *<nr>* value specified will be **added** to the generated
1160 offset for each I/O turning sequential I/O into sequential I/O with holes.
1161 For instance, using ``rw=write:4k`` will skip 4k for every write. Also see
1162 the :option:`rw_sequencer` option.
1164 .. option:: rw_sequencer=str
1166 If an offset modifier is given by appending a number to the ``rw=<str>``
1167 line, then this option controls how that number modifies the I/O offset
1168 being generated. Accepted values are:
1171 Generate sequential offset.
1173 Generate the same offset.
1175 ``sequential`` is only useful for random I/O, where fio would normally
1176 generate a new random offset for every I/O. If you append e.g. 8 to
1177 randread, i.e. ``rw=randread:8`` you would get a new random offset for
1178 every 8 I/Os. The result would be a sequence of 8 sequential offsets
1179 with a random starting point. However this behavior may change if a
1180 sequential I/O reaches end of the file. As sequential I/O is already
1181 sequential, setting ``sequential`` for that would not result in any
1182 difference. ``identical`` behaves in a similar fashion, except it sends
1183 the same offset 8 number of times before generating a new offset.
1188 rw_sequencer=sequential
1191 The generated sequence of offsets will look like this:
1192 4k, 8k, 12k, 16k, 20k, 24k, 28k, 32k, 92k, 96k, 100k, 104k, 108k,
1193 112k, 116k, 120k, 48k, 52k ...
1198 rw_sequencer=identical
1201 The generated sequence of offsets will look like this:
1202 4k, 4k, 4k, 4k, 4k, 4k, 4k, 4k, 92k, 92k, 92k, 92k, 92k, 92k, 92k, 92k,
1205 .. option:: unified_rw_reporting=str
1207 Fio normally reports statistics on a per data direction basis, meaning that
1208 reads, writes, and trims are accounted and reported separately. This option
1209 determines whether fio reports the results normally, summed together, or as
1211 Accepted values are:
1214 Normal statistics reporting.
1217 Statistics are summed per data direction and reported together.
1220 Statistics are reported normally, followed by the mixed statistics.
1223 Backward-compatible alias for **none**.
1226 Backward-compatible alias for **mixed**.
1231 .. option:: randrepeat=bool
1233 Seed the random number generator used for random I/O patterns in a
1234 predictable way so the pattern is repeatable across runs. Default: true.
1236 .. option:: allrandrepeat=bool
1238 Seed all random number generators in a predictable way so results are
1239 repeatable across runs. Default: false.
1241 .. option:: randseed=int
1243 Seed the random number generators based on this seed value, to be able to
1244 control what sequence of output is being generated. If not set, the random
1245 sequence depends on the :option:`randrepeat` setting.
1247 .. option:: fallocate=str
1249 Whether pre-allocation is performed when laying down files.
1250 Accepted values are:
1253 Do not pre-allocate space.
1256 Use a platform's native pre-allocation call but fall back to
1257 **none** behavior if it fails/is not implemented.
1260 Pre-allocate via :manpage:`posix_fallocate(3)`.
1263 Pre-allocate via :manpage:`fallocate(2)` with
1264 FALLOC_FL_KEEP_SIZE set.
1267 Extend file to final size via :manpage:`ftruncate(2)`
1268 instead of allocating.
1271 Backward-compatible alias for **none**.
1274 Backward-compatible alias for **posix**.
1276 May not be available on all supported platforms. **keep** is only available
1277 on Linux. If using ZFS on Solaris this cannot be set to **posix**
1278 because ZFS doesn't support pre-allocation. Default: **native** if any
1279 pre-allocation methods except **truncate** are available, **none** if not.
1281 Note that using **truncate** on Windows will interact surprisingly
1282 with non-sequential write patterns. When writing to a file that has
1283 been extended by setting the end-of-file information, Windows will
1284 backfill the unwritten portion of the file up to that offset with
1285 zeroes before issuing the new write. This means that a single small
1286 write to the end of an extended file will stall until the entire
1287 file has been filled with zeroes.
1289 .. option:: fadvise_hint=str
1291 Use :manpage:`posix_fadvise(2)` or :manpage:`posix_fadvise(2)` to
1292 advise the kernel on what I/O patterns are likely to be issued.
1293 Accepted values are:
1296 Backwards-compatible hint for "no hint".
1299 Backwards compatible hint for "advise with fio workload type". This
1300 uses **FADV_RANDOM** for a random workload, and **FADV_SEQUENTIAL**
1301 for a sequential workload.
1304 Advise using **FADV_SEQUENTIAL**.
1307 Advise using **FADV_RANDOM**.
1309 .. option:: write_hint=str
1311 Use :manpage:`fcntl(2)` to advise the kernel what life time to expect
1312 from a write. Only supported on Linux, as of version 4.13. Accepted
1316 No particular life time associated with this file.
1319 Data written to this file has a short life time.
1322 Data written to this file has a medium life time.
1325 Data written to this file has a long life time.
1328 Data written to this file has a very long life time.
1330 The values are all relative to each other, and no absolute meaning
1331 should be associated with them.
1333 .. option:: offset=int
1335 Start I/O at the provided offset in the file, given as either a fixed size in
1336 bytes, zones or a percentage. If a percentage is given, the generated offset will be
1337 aligned to the minimum ``blocksize`` or to the value of ``offset_align`` if
1338 provided. Data before the given offset will not be touched. This
1339 effectively caps the file size at `real_size - offset`. Can be combined with
1340 :option:`size` to constrain the start and end range of the I/O workload.
1341 A percentage can be specified by a number between 1 and 100 followed by '%',
1342 for example, ``offset=20%`` to specify 20%. In ZBD mode, value can be set as
1343 number of zones using 'z'.
1345 .. option:: offset_align=int
1347 If set to non-zero value, the byte offset generated by a percentage ``offset``
1348 is aligned upwards to this value. Defaults to 0 meaning that a percentage
1349 offset is aligned to the minimum block size.
1351 .. option:: offset_increment=int
1353 If this is provided, then the real offset becomes `offset + offset_increment
1354 * thread_number`, where the thread number is a counter that starts at 0 and
1355 is incremented for each sub-job (i.e. when :option:`numjobs` option is
1356 specified). This option is useful if there are several jobs which are
1357 intended to operate on a file in parallel disjoint segments, with even
1358 spacing between the starting points. Percentages can be used for this option.
1359 If a percentage is given, the generated offset will be aligned to the minimum
1360 ``blocksize`` or to the value of ``offset_align`` if provided. In ZBD mode, value can
1361 also be set as number of zones using 'z'.
1363 .. option:: number_ios=int
1365 Fio will normally perform I/Os until it has exhausted the size of the region
1366 set by :option:`size`, or if it exhaust the allocated time (or hits an error
1367 condition). With this setting, the range/size can be set independently of
1368 the number of I/Os to perform. When fio reaches this number, it will exit
1369 normally and report status. Note that this does not extend the amount of I/O
1370 that will be done, it will only stop fio if this condition is met before
1371 other end-of-job criteria.
1373 .. option:: fsync=int
1375 If writing to a file, issue an :manpage:`fsync(2)` (or its equivalent) of
1376 the dirty data for every number of blocks given. For example, if you give 32
1377 as a parameter, fio will sync the file after every 32 writes issued. If fio is
1378 using non-buffered I/O, we may not sync the file. The exception is the sg
1379 I/O engine, which synchronizes the disk cache anyway. Defaults to 0, which
1380 means fio does not periodically issue and wait for a sync to complete. Also
1381 see :option:`end_fsync` and :option:`fsync_on_close`.
1383 .. option:: fdatasync=int
1385 Like :option:`fsync` but uses :manpage:`fdatasync(2)` to only sync data and
1386 not metadata blocks. In Windows, DragonFlyBSD or OSX there is no
1387 :manpage:`fdatasync(2)` so this falls back to using :manpage:`fsync(2)`.
1388 Defaults to 0, which means fio does not periodically issue and wait for a
1389 data-only sync to complete.
1391 .. option:: write_barrier=int
1393 Make every `N-th` write a barrier write.
1395 .. option:: sync_file_range=str:int
1397 Use :manpage:`sync_file_range(2)` for every `int` number of write
1398 operations. Fio will track range of writes that have happened since the last
1399 :manpage:`sync_file_range(2)` call. `str` can currently be one or more of:
1402 SYNC_FILE_RANGE_WAIT_BEFORE
1404 SYNC_FILE_RANGE_WRITE
1406 SYNC_FILE_RANGE_WAIT_AFTER
1408 So if you do ``sync_file_range=wait_before,write:8``, fio would use
1409 ``SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE`` for every 8
1410 writes. Also see the :manpage:`sync_file_range(2)` man page. This option is
1413 .. option:: overwrite=bool
1415 If true, writes to a file will always overwrite existing data. If the file
1416 doesn't already exist, it will be created before the write phase begins. If
1417 the file exists and is large enough for the specified write phase, nothing
1418 will be done. Default: false.
1420 .. option:: end_fsync=bool
1422 If true, :manpage:`fsync(2)` file contents when a write stage has completed.
1425 .. option:: fsync_on_close=bool
1427 If true, fio will :manpage:`fsync(2)` a dirty file on close. This differs
1428 from :option:`end_fsync` in that it will happen on every file close, not
1429 just at the end of the job. Default: false.
1431 .. option:: rwmixread=int
1433 Percentage of a mixed workload that should be reads. Default: 50.
1435 .. option:: rwmixwrite=int
1437 Percentage of a mixed workload that should be writes. If both
1438 :option:`rwmixread` and :option:`rwmixwrite` is given and the values do not
1439 add up to 100%, the latter of the two will be used to override the
1440 first. This may interfere with a given rate setting, if fio is asked to
1441 limit reads or writes to a certain rate. If that is the case, then the
1442 distribution may be skewed. Default: 50.
1444 .. option:: random_distribution=str:float[:float][,str:float][,str:float]
1446 By default, fio will use a completely uniform random distribution when asked
1447 to perform random I/O. Sometimes it is useful to skew the distribution in
1448 specific ways, ensuring that some parts of the data is more hot than others.
1449 fio includes the following distribution models:
1452 Uniform random distribution
1461 Normal (Gaussian) distribution
1464 Zoned random distribution
1467 Zone absolute random distribution
1469 When using a **zipf** or **pareto** distribution, an input value is also
1470 needed to define the access pattern. For **zipf**, this is the `Zipf
1471 theta`. For **pareto**, it's the `Pareto power`. Fio includes a test
1472 program, :command:`fio-genzipf`, that can be used visualize what the given input
1473 values will yield in terms of hit rates. If you wanted to use **zipf** with
1474 a `theta` of 1.2, you would use ``random_distribution=zipf:1.2`` as the
1475 option. If a non-uniform model is used, fio will disable use of the random
1476 map. For the **normal** distribution, a normal (Gaussian) deviation is
1477 supplied as a value between 0 and 100.
1479 The second, optional float is allowed for **pareto**, **zipf** and **normal** distributions.
1480 It allows one to set base of distribution in non-default place, giving more control
1481 over most probable outcome. This value is in range [0-1] which maps linearly to
1482 range of possible random values.
1483 Defaults are: random for **pareto** and **zipf**, and 0.5 for **normal**.
1484 If you wanted to use **zipf** with a `theta` of 1.2 centered on 1/4 of allowed value range,
1485 you would use ``random_distribution=zipf:1.2:0.25``.
1487 For a **zoned** distribution, fio supports specifying percentages of I/O
1488 access that should fall within what range of the file or device. For
1489 example, given a criteria of:
1491 * 60% of accesses should be to the first 10%
1492 * 30% of accesses should be to the next 20%
1493 * 8% of accesses should be to the next 30%
1494 * 2% of accesses should be to the next 40%
1496 we can define that through zoning of the random accesses. For the above
1497 example, the user would do::
1499 random_distribution=zoned:60/10:30/20:8/30:2/40
1501 A **zoned_abs** distribution works exactly like the **zoned**, except
1502 that it takes absolute sizes. For example, let's say you wanted to
1503 define access according to the following criteria:
1505 * 60% of accesses should be to the first 20G
1506 * 30% of accesses should be to the next 100G
1507 * 10% of accesses should be to the next 500G
1509 we can define an absolute zoning distribution with:
1511 random_distribution=zoned_abs=60/20G:30/100G:10/500g
1513 For both **zoned** and **zoned_abs**, fio supports defining up to
1516 Similarly to how :option:`bssplit` works for setting ranges and
1517 percentages of block sizes. Like :option:`bssplit`, it's possible to
1518 specify separate zones for reads, writes, and trims. If just one set
1519 is given, it'll apply to all of them. This goes for both **zoned**
1520 **zoned_abs** distributions.
1522 .. option:: percentage_random=int[,int][,int]
1524 For a random workload, set how big a percentage should be random. This
1525 defaults to 100%, in which case the workload is fully random. It can be set
1526 from anywhere from 0 to 100. Setting it to 0 would make the workload fully
1527 sequential. Any setting in between will result in a random mix of sequential
1528 and random I/O, at the given percentages. Comma-separated values may be
1529 specified for reads, writes, and trims as described in :option:`blocksize`.
1531 .. option:: norandommap
1533 Normally fio will cover every block of the file when doing random I/O. If
1534 this option is given, fio will just get a new random offset without looking
1535 at past I/O history. This means that some blocks may not be read or written,
1536 and that some blocks may be read/written more than once. If this option is
1537 used with :option:`verify` and multiple blocksizes (via :option:`bsrange`),
1538 only intact blocks are verified, i.e., partially-overwritten blocks are
1539 ignored. With an async I/O engine and an I/O depth > 1, it is possible for
1540 the same block to be overwritten, which can cause verification errors. Either
1541 do not use norandommap in this case, or also use the lfsr random generator.
1543 .. option:: softrandommap=bool
1545 See :option:`norandommap`. If fio runs with the random block map enabled and
1546 it fails to allocate the map, if this option is set it will continue without
1547 a random block map. As coverage will not be as complete as with random maps,
1548 this option is disabled by default.
1550 .. option:: random_generator=str
1552 Fio supports the following engines for generating I/O offsets for random I/O:
1555 Strong 2^88 cycle random number generator.
1557 Linear feedback shift register generator.
1559 Strong 64-bit 2^258 cycle random number generator.
1561 **tausworthe** is a strong random number generator, but it requires tracking
1562 on the side if we want to ensure that blocks are only read or written
1563 once. **lfsr** guarantees that we never generate the same offset twice, and
1564 it's also less computationally expensive. It's not a true random generator,
1565 however, though for I/O purposes it's typically good enough. **lfsr** only
1566 works with single block sizes, not with workloads that use multiple block
1567 sizes. If used with such a workload, fio may read or write some blocks
1568 multiple times. The default value is **tausworthe**, unless the required
1569 space exceeds 2^32 blocks. If it does, then **tausworthe64** is
1570 selected automatically.
1576 .. option:: blocksize=int[,int][,int], bs=int[,int][,int]
1578 The block size in bytes used for I/O units. Default: 4096. A single value
1579 applies to reads, writes, and trims. Comma-separated values may be
1580 specified for reads, writes, and trims. A value not terminated in a comma
1581 applies to subsequent types.
1586 means 256k for reads, writes and trims.
1589 means 8k for reads, 32k for writes and trims.
1592 means 8k for reads, 32k for writes, and default for trims.
1595 means default for reads, 8k for writes and trims.
1598 means default for reads, 8k for writes, and default for trims.
1600 .. option:: blocksize_range=irange[,irange][,irange], bsrange=irange[,irange][,irange]
1602 A range of block sizes in bytes for I/O units. The issued I/O unit will
1603 always be a multiple of the minimum size, unless
1604 :option:`blocksize_unaligned` is set.
1606 Comma-separated ranges may be specified for reads, writes, and trims as
1607 described in :option:`blocksize`.
1609 Example: ``bsrange=1k-4k,2k-8k``.
1611 .. option:: bssplit=str[,str][,str]
1613 Sometimes you want even finer grained control of the block sizes
1614 issued, not just an even split between them. This option allows you to
1615 weight various block sizes, so that you are able to define a specific
1616 amount of block sizes issued. The format for this option is::
1618 bssplit=blocksize/percentage:blocksize/percentage
1620 for as many block sizes as needed. So if you want to define a workload
1621 that has 50% 64k blocks, 10% 4k blocks, and 40% 32k blocks, you would
1624 bssplit=4k/10:64k/50:32k/40
1626 Ordering does not matter. If the percentage is left blank, fio will
1627 fill in the remaining values evenly. So a bssplit option like this one::
1629 bssplit=4k/50:1k/:32k/
1631 would have 50% 4k ios, and 25% 1k and 32k ios. The percentages always
1632 add up to 100, if bssplit is given a range that adds up to more, it
1635 Comma-separated values may be specified for reads, writes, and trims as
1636 described in :option:`blocksize`.
1638 If you want a workload that has 50% 2k reads and 50% 4k reads, while
1639 having 90% 4k writes and 10% 8k writes, you would specify::
1641 bssplit=2k/50:4k/50,4k/90:8k/10
1643 Fio supports defining up to 64 different weights for each data
1646 .. option:: blocksize_unaligned, bs_unaligned
1648 If set, fio will issue I/O units with any size within
1649 :option:`blocksize_range`, not just multiples of the minimum size. This
1650 typically won't work with direct I/O, as that normally requires sector
1653 .. option:: bs_is_seq_rand=bool
1655 If this option is set, fio will use the normal read,write blocksize settings
1656 as sequential,random blocksize settings instead. Any random read or write
1657 will use the WRITE blocksize settings, and any sequential read or write will
1658 use the READ blocksize settings.
1660 .. option:: blockalign=int[,int][,int], ba=int[,int][,int]
1662 Boundary to which fio will align random I/O units. Default:
1663 :option:`blocksize`. Minimum alignment is typically 512b for using direct
1664 I/O, though it usually depends on the hardware block size. This option is
1665 mutually exclusive with using a random map for files, so it will turn off
1666 that option. Comma-separated values may be specified for reads, writes, and
1667 trims as described in :option:`blocksize`.
1673 .. option:: zero_buffers
1675 Initialize buffers with all zeros. Default: fill buffers with random data.
1677 .. option:: refill_buffers
1679 If this option is given, fio will refill the I/O buffers on every
1680 submit. Only makes sense if :option:`zero_buffers` isn't specified,
1681 naturally. Defaults to being unset i.e., the buffer is only filled at
1682 init time and the data in it is reused when possible but if any of
1683 :option:`verify`, :option:`buffer_compress_percentage` or
1684 :option:`dedupe_percentage` are enabled then `refill_buffers` is also
1685 automatically enabled.
1687 .. option:: scramble_buffers=bool
1689 If :option:`refill_buffers` is too costly and the target is using data
1690 deduplication, then setting this option will slightly modify the I/O buffer
1691 contents to defeat normal de-dupe attempts. This is not enough to defeat
1692 more clever block compression attempts, but it will stop naive dedupe of
1693 blocks. Default: true.
1695 .. option:: buffer_compress_percentage=int
1697 If this is set, then fio will attempt to provide I/O buffer content
1698 (on WRITEs) that compresses to the specified level. Fio does this by
1699 providing a mix of random data followed by fixed pattern data. The
1700 fixed pattern is either zeros, or the pattern specified by
1701 :option:`buffer_pattern`. If the `buffer_pattern` option is used, it
1702 might skew the compression ratio slightly. Setting
1703 `buffer_compress_percentage` to a value other than 100 will also
1704 enable :option:`refill_buffers` in order to reduce the likelihood that
1705 adjacent blocks are so similar that they over compress when seen
1706 together. See :option:`buffer_compress_chunk` for how to set a finer or
1707 coarser granularity for the random/fixed data region. Defaults to unset
1708 i.e., buffer data will not adhere to any compression level.
1710 .. option:: buffer_compress_chunk=int
1712 This setting allows fio to manage how big the random/fixed data region
1713 is when using :option:`buffer_compress_percentage`. When
1714 `buffer_compress_chunk` is set to some non-zero value smaller than the
1715 block size, fio can repeat the random/fixed region throughout the I/O
1716 buffer at the specified interval (which particularly useful when
1717 bigger block sizes are used for a job). When set to 0, fio will use a
1718 chunk size that matches the block size resulting in a single
1719 random/fixed region within the I/O buffer. Defaults to 512. When the
1720 unit is omitted, the value is interpreted in bytes.
1722 .. option:: buffer_pattern=str
1724 If set, fio will fill the I/O buffers with this pattern or with the contents
1725 of a file. If not set, the contents of I/O buffers are defined by the other
1726 options related to buffer contents. The setting can be any pattern of bytes,
1727 and can be prefixed with 0x for hex values. It may also be a string, where
1728 the string must then be wrapped with ``""``. Or it may also be a filename,
1729 where the filename must be wrapped with ``''`` in which case the file is
1730 opened and read. Note that not all the file contents will be read if that
1731 would cause the buffers to overflow. So, for example::
1733 buffer_pattern='filename'
1737 buffer_pattern="abcd"
1745 buffer_pattern=0xdeadface
1747 Also you can combine everything together in any order::
1749 buffer_pattern=0xdeadface"abcd"-12'filename'
1751 .. option:: dedupe_percentage=int
1753 If set, fio will generate this percentage of identical buffers when
1754 writing. These buffers will be naturally dedupable. The contents of the
1755 buffers depend on what other buffer compression settings have been set. It's
1756 possible to have the individual buffers either fully compressible, or not at
1757 all -- this option only controls the distribution of unique buffers. Setting
1758 this option will also enable :option:`refill_buffers` to prevent every buffer
1761 .. option:: dedupe_mode=str
1763 If ``dedupe_percentage=<int>`` is given, then this option controls how fio
1764 generates the dedupe buffers.
1767 Generate dedupe buffers by repeating previous writes
1769 Generate dedupe buffers from working set
1771 ``repeat`` is the default option for fio. Dedupe buffers are generated
1772 by repeating previous unique write.
1774 ``working_set`` is a more realistic workload.
1775 With ``working_set``, ``dedupe_working_set_percentage=<int>`` should be provided.
1776 Given that, fio will use the initial unique write buffers as its working set.
1777 Upon deciding to dedupe, fio will randomly choose a buffer from the working set.
1778 Note that by using ``working_set`` the dedupe percentage will converge
1779 to the desired over time while ``repeat`` maintains the desired percentage
1782 .. option:: dedupe_working_set_percentage=int
1784 If ``dedupe_mode=<str>`` is set to ``working_set``, then this controls
1785 the percentage of size of the file or device used as the buffers
1786 fio will choose to generate the dedupe buffers from
1788 Note that size needs to be explicitly provided and only 1 file per
1791 .. option:: dedupe_global=bool
1793 This controls whether the deduplication buffers will be shared amongst
1794 all jobs that have this option set. The buffers are spread evenly between
1797 .. option:: invalidate=bool
1799 Invalidate the buffer/page cache parts of the files to be used prior to
1800 starting I/O if the platform and file type support it. Defaults to true.
1801 This will be ignored if :option:`pre_read` is also specified for the
1804 .. option:: sync=str
1806 Whether, and what type, of synchronous I/O to use for writes. The allowed
1810 Do not use synchronous IO, the default.
1816 Use synchronous file IO. For the majority of I/O engines,
1817 this means using O_SYNC.
1823 Use synchronous data IO. For the majority of I/O engines,
1824 this means using O_DSYNC.
1827 .. option:: iomem=str, mem=str
1829 Fio can use various types of memory as the I/O unit buffer. The allowed
1833 Use memory from :manpage:`malloc(3)` as the buffers. Default memory
1837 Use shared memory as the buffers. Allocated through
1838 :manpage:`shmget(2)`.
1841 Same as shm, but use huge pages as backing.
1844 Use :manpage:`mmap(2)` to allocate buffers. May either be anonymous memory, or can
1845 be file backed if a filename is given after the option. The format
1846 is `mem=mmap:/path/to/file`.
1849 Use a memory mapped huge file as the buffer backing. Append filename
1850 after mmaphuge, ala `mem=mmaphuge:/hugetlbfs/file`.
1853 Same as mmap, but use a MMAP_SHARED mapping.
1856 Use GPU memory as the buffers for GPUDirect RDMA benchmark.
1857 The :option:`ioengine` must be `rdma`.
1859 The area allocated is a function of the maximum allowed bs size for the job,
1860 multiplied by the I/O depth given. Note that for **shmhuge** and
1861 **mmaphuge** to work, the system must have free huge pages allocated. This
1862 can normally be checked and set by reading/writing
1863 :file:`/proc/sys/vm/nr_hugepages` on a Linux system. Fio assumes a huge page
1864 is 2 or 4MiB in size depending on the platform. So to calculate the
1865 number of huge pages you need for a given job file, add up the I/O
1866 depth of all jobs (normally one unless :option:`iodepth` is used) and
1867 multiply by the maximum bs set. Then divide that number by the huge
1868 page size. You can see the size of the huge pages in
1869 :file:`/proc/meminfo`. If no huge pages are allocated by having a
1870 non-zero number in `nr_hugepages`, using **mmaphuge** or **shmhuge**
1871 will fail. Also see :option:`hugepage-size`.
1873 **mmaphuge** also needs to have hugetlbfs mounted and the file location
1874 should point there. So if it's mounted in :file:`/huge`, you would use
1875 `mem=mmaphuge:/huge/somefile`.
1877 .. option:: iomem_align=int, mem_align=int
1879 This indicates the memory alignment of the I/O memory buffers. Note that
1880 the given alignment is applied to the first I/O unit buffer, if using
1881 :option:`iodepth` the alignment of the following buffers are given by the
1882 :option:`bs` used. In other words, if using a :option:`bs` that is a
1883 multiple of the page sized in the system, all buffers will be aligned to
1884 this value. If using a :option:`bs` that is not page aligned, the alignment
1885 of subsequent I/O memory buffers is the sum of the :option:`iomem_align` and
1888 .. option:: hugepage-size=int
1890 Defines the size of a huge page. Must at least be equal to the system
1891 setting, see :file:`/proc/meminfo` and
1892 :file:`/sys/kernel/mm/hugepages/`. Defaults to 2 or 4MiB depending on
1893 the platform. Should probably always be a multiple of megabytes, so
1894 using ``hugepage-size=Xm`` is the preferred way to set this to avoid
1895 setting a non-pow-2 bad value.
1897 .. option:: lockmem=int
1899 Pin the specified amount of memory with :manpage:`mlock(2)`. Can be used to
1900 simulate a smaller amount of memory. The amount specified is per worker.
1906 .. option:: size=int
1908 The total size of file I/O for each thread of this job. Fio will run until
1909 this many bytes has been transferred, unless runtime is altered by other means
1910 such as (1) :option:`runtime`, (2) :option:`io_size` (3) :option:`number_ios`,
1911 (4) gaps/holes while doing I/O's such as ``rw=read:16K``, or (5) sequential
1912 I/O reaching end of the file which is possible when :option:`percentage_random`
1914 Fio will divide this size between the available files determined by options
1915 such as :option:`nrfiles`, :option:`filename`, unless :option:`filesize` is
1916 specified by the job. If the result of division happens to be 0, the size is
1917 set to the physical size of the given files or devices if they exist.
1918 If this option is not specified, fio will use the full size of the given
1919 files or devices. If the files do not exist, size must be given. It is also
1920 possible to give size as a percentage between 1 and 100. If ``size=20%`` is
1921 given, fio will use 20% of the full size of the given files or devices.
1922 In ZBD mode, value can also be set as number of zones using 'z'.
1923 Can be combined with :option:`offset` to constrain the start and end range
1924 that I/O will be done within.
1926 .. option:: io_size=int, io_limit=int
1928 Normally fio operates within the region set by :option:`size`, which means
1929 that the :option:`size` option sets both the region and size of I/O to be
1930 performed. Sometimes that is not what you want. With this option, it is
1931 possible to define just the amount of I/O that fio should do. For instance,
1932 if :option:`size` is set to 20GiB and :option:`io_size` is set to 5GiB, fio
1933 will perform I/O within the first 20GiB but exit when 5GiB have been
1934 done. The opposite is also possible -- if :option:`size` is set to 20GiB,
1935 and :option:`io_size` is set to 40GiB, then fio will do 40GiB of I/O within
1936 the 0..20GiB region.
1938 .. option:: filesize=irange(int)
1940 Individual file sizes. May be a range, in which case fio will select sizes for
1941 files at random within the given range. If not given, each created file is the
1942 same size. This option overrides :option:`size` in terms of file size, i.e. if
1943 :option:`filesize` is specified then :option:`size` becomes merely the default
1944 for :option:`io_size` and has no effect at all if :option:`io_size` is set
1947 .. option:: file_append=bool
1949 Perform I/O after the end of the file. Normally fio will operate within the
1950 size of a file. If this option is set, then fio will append to the file
1951 instead. This has identical behavior to setting :option:`offset` to the size
1952 of a file. This option is ignored on non-regular files.
1954 .. option:: fill_device=bool, fill_fs=bool
1956 Sets size to something really large and waits for ENOSPC (no space left on
1957 device) or EDQUOT (disk quota exceeded)
1958 as the terminating condition. Only makes sense with sequential
1959 write. For a read workload, the mount point will be filled first then I/O
1960 started on the result. This option doesn't make sense if operating on a raw
1961 device node, since the size of that is already known by the file system.
1962 Additionally, writing beyond end-of-device will not return ENOSPC there.
1968 .. option:: ioengine=str
1970 Defines how the job issues I/O to the file. The following types are defined:
1973 Basic :manpage:`read(2)` or :manpage:`write(2)`
1974 I/O. :manpage:`lseek(2)` is used to position the I/O location.
1975 See :option:`fsync` and :option:`fdatasync` for syncing write I/Os.
1978 Basic :manpage:`pread(2)` or :manpage:`pwrite(2)` I/O. Default on
1979 all supported operating systems except for Windows.
1982 Basic :manpage:`readv(2)` or :manpage:`writev(2)` I/O. Will emulate
1983 queuing by coalescing adjacent I/Os into a single submission.
1986 Basic :manpage:`preadv(2)` or :manpage:`pwritev(2)` I/O.
1989 Basic :manpage:`preadv2(2)` or :manpage:`pwritev2(2)` I/O.
1992 Fast Linux native asynchronous I/O. Supports async IO
1993 for both direct and buffered IO.
1994 This engine defines engine specific options.
1997 Fast Linux native asynchronous I/O for pass through commands.
1998 This engine defines engine specific options.
2001 Linux native asynchronous I/O. Note that Linux may only support
2002 queued behavior with non-buffered I/O (set ``direct=1`` or
2004 This engine defines engine specific options.
2007 POSIX asynchronous I/O using :manpage:`aio_read(3)` and
2008 :manpage:`aio_write(3)`.
2011 Solaris native asynchronous I/O.
2014 Windows native asynchronous I/O. Default on Windows.
2017 File is memory mapped with :manpage:`mmap(2)` and data copied
2018 to/from using :manpage:`memcpy(3)`.
2021 :manpage:`splice(2)` is used to transfer the data and
2022 :manpage:`vmsplice(2)` to transfer data from user space to the
2026 SCSI generic sg v3 I/O. May either be synchronous using the SG_IO
2027 ioctl, or if the target is an sg character device we use
2028 :manpage:`read(2)` and :manpage:`write(2)` for asynchronous
2029 I/O. Requires :option:`filename` option to specify either block or
2030 character devices. This engine supports trim operations.
2031 The sg engine includes engine specific options.
2034 Read, write, trim and ZBC/ZAC operations to a zoned
2035 block device using libzbc library. The target can be
2036 either an SG character device or a block device file.
2039 Doesn't transfer any data, just pretends to. This is mainly used to
2040 exercise fio itself and for debugging/testing purposes.
2043 Transfer over the network to given ``host:port``. Depending on the
2044 :option:`protocol` used, the :option:`hostname`, :option:`port`,
2045 :option:`listen` and :option:`filename` options are used to specify
2046 what sort of connection to make, while the :option:`protocol` option
2047 determines which protocol will be used. This engine defines engine
2051 Like **net**, but uses :manpage:`splice(2)` and
2052 :manpage:`vmsplice(2)` to map data and send/receive.
2053 This engine defines engine specific options.
2056 Doesn't transfer any data, but burns CPU cycles according to the
2057 :option:`cpuload`, :option:`cpuchunks` and :option:`cpumode` options.
2058 Setting :option:`cpuload`\=85 will cause that job to do nothing but burn 85%
2059 of the CPU. In case of SMP machines, use :option:`numjobs`\=<nr_of_cpu>
2060 to get desired CPU usage, as the cpuload only loads a
2061 single CPU at the desired rate. A job never finishes unless there is
2062 at least one non-cpuio job.
2063 Setting :option:`cpumode`\=qsort replace the default noop instructions loop
2064 by a qsort algorithm to consume more energy.
2067 The RDMA I/O engine supports both RDMA memory semantics
2068 (RDMA_WRITE/RDMA_READ) and channel semantics (Send/Recv) for the
2069 InfiniBand, RoCE and iWARP protocols. This engine defines engine
2073 I/O engine that does regular fallocate to simulate data transfer as
2077 does fallocate(,mode = FALLOC_FL_KEEP_SIZE,).
2080 does fallocate(,mode = 0).
2083 does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE).
2086 I/O engine that sends :manpage:`ftruncate(2)` operations in response
2087 to write (DDIR_WRITE) events. Each ftruncate issued sets the file's
2088 size to the current block offset. :option:`blocksize` is ignored.
2091 I/O engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate
2092 defragment activity in request to DDIR_WRITE event.
2095 I/O engine supporting direct access to Ceph Reliable Autonomic
2096 Distributed Object Store (RADOS) via librados. This ioengine
2097 defines engine specific options.
2100 I/O engine supporting direct access to Ceph Rados Block Devices
2101 (RBD) via librbd without the need to use the kernel rbd driver. This
2102 ioengine defines engine specific options.
2105 I/O engine supporting GET/PUT requests over HTTP(S) with libcurl to
2106 a WebDAV or S3 endpoint. This ioengine defines engine specific options.
2108 This engine only supports direct IO of iodepth=1; you need to scale this
2109 via numjobs. blocksize defines the size of the objects to be created.
2111 TRIM is translated to object deletion.
2114 Using GlusterFS libgfapi sync interface to direct access to
2115 GlusterFS volumes without having to go through FUSE. This ioengine
2116 defines engine specific options.
2119 Using GlusterFS libgfapi async interface to direct access to
2120 GlusterFS volumes without having to go through FUSE. This ioengine
2121 defines engine specific options.
2124 Read and write through Hadoop (HDFS). The :option:`filename` option
2125 is used to specify host,port of the hdfs name-node to connect. This
2126 engine interprets offsets a little differently. In HDFS, files once
2127 created cannot be modified so random writes are not possible. To
2128 imitate this the libhdfs engine expects a bunch of small files to be
2129 created over HDFS and will randomly pick a file from them
2130 based on the offset generated by fio backend (see the example
2131 job file to create such files, use ``rw=write`` option). Please
2132 note, it may be necessary to set environment variables to work
2133 with HDFS/libhdfs properly. Each job uses its own connection to
2137 Read, write and erase an MTD character device (e.g.,
2138 :file:`/dev/mtd0`). Discards are treated as erases. Depending on the
2139 underlying device type, the I/O may have to go in a certain pattern,
2140 e.g., on NAND, writing sequentially to erase blocks and discarding
2141 before overwriting. The `trimwrite` mode works well for this
2145 Read and write using filesystem DAX to a file on a filesystem
2146 mounted with DAX on a persistent memory device through the PMDK
2150 Read and write using device DAX to a persistent memory device (e.g.,
2151 /dev/dax0.0) through the PMDK libpmem library.
2154 Prefix to specify loading an external I/O engine object file. Append
2155 the engine filename, e.g. ``ioengine=external:/tmp/foo.o`` to load
2156 ioengine :file:`foo.o` in :file:`/tmp`. The path can be either
2157 absolute or relative. See :file:`engines/skeleton_external.c` for
2158 details of writing an external I/O engine.
2161 Simply create the files and do no I/O to them. You still need to
2162 set `filesize` so that all the accounting still occurs, but no
2163 actual I/O will be done other than creating the file.
2166 Simply do stat() and do no I/O to the file. You need to set 'filesize'
2167 and 'nrfiles', so that files will be created.
2168 This engine is to measure file lookup and meta data access.
2171 Simply delete the files by unlink() and do no I/O to them. You need to set 'filesize'
2172 and 'nrfiles', so that the files will be created.
2173 This engine is to measure file delete.
2176 Read and write using mmap I/O to a file on a filesystem
2177 mounted with DAX on a persistent memory device through the PMDK
2181 Synchronous read and write using DDN's Infinite Memory Engine (IME).
2182 This engine is very basic and issues calls to IME whenever an IO is
2186 Synchronous read and write using DDN's Infinite Memory Engine (IME).
2187 This engine uses iovecs and will try to stack as much IOs as possible
2188 (if the IOs are "contiguous" and the IO depth is not exceeded)
2189 before issuing a call to IME.
2192 Asynchronous read and write using DDN's Infinite Memory Engine (IME).
2193 This engine will try to stack as much IOs as possible by creating
2194 requests for IME. FIO will then decide when to commit these requests.
2197 Read and write iscsi lun with libiscsi.
2200 Read and write a Network Block Device (NBD).
2203 I/O engine supporting libcufile synchronous access to nvidia-fs and a
2204 GPUDirect Storage-supported filesystem. This engine performs
2205 I/O without transferring buffers between user-space and the kernel,
2206 unless :option:`verify` is set or :option:`cuda_io` is `posix`.
2207 :option:`iomem` must not be `cudamalloc`. This ioengine defines
2208 engine specific options.
2211 I/O engine supporting asynchronous read and write operations to the
2212 DAOS File System (DFS) via libdfs.
2215 I/O engine supporting asynchronous read and write operations to
2216 NFS filesystems from userspace via libnfs. This is useful for
2217 achieving higher concurrency and thus throughput than is possible
2221 Execute 3rd party tools. Could be used to perform monitoring during jobs runtime.
2224 I/O engine using the xNVMe C API, for NVMe devices. The xnvme engine provides
2225 flexibility to access GNU/Linux Kernel NVMe driver via libaio, IOCTLs, io_uring,
2226 the SPDK NVMe driver, or your own custom NVMe driver. The xnvme engine includes
2227 engine specific options. (See https://xnvme.io).
2230 Use the libblkio library
2231 (https://gitlab.com/libblkio/libblkio). The specific
2232 *driver* to use must be set using
2233 :option:`libblkio_driver`. If
2234 :option:`mem`/:option:`iomem` is not specified, memory
2235 allocation is delegated to libblkio (and so is
2236 guaranteed to work with the selected *driver*). One
2237 libblkio instance is used per process, so all jobs
2238 setting option :option:`thread` will share a single
2239 instance (with one queue per thread) and must specify
2240 compatible options. Note that some drivers don't allow
2241 several instances to access the same device or file
2242 simultaneously, but allow it for threads.
2244 I/O engine specific parameters
2245 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2247 In addition, there are some parameters which are only valid when a specific
2248 :option:`ioengine` is in use. These are used identically to normal parameters,
2249 with the caveat that when used on the command line, they must come after the
2250 :option:`ioengine` that defines them is selected.
2252 .. option:: cmdprio_percentage=int[,int] : [io_uring] [libaio]
2254 Set the percentage of I/O that will be issued with the highest priority.
2255 Default: 0. A single value applies to reads and writes. Comma-separated
2256 values may be specified for reads and writes. For this option to be
2257 effective, NCQ priority must be supported and enabled, and the :option:`direct`
2258 option must be set. fio must also be run as the root user. Unlike
2259 slat/clat/lat stats, which can be tracked and reported independently, per
2260 priority stats only track and report a single type of latency. By default,
2261 completion latency (clat) will be reported, if :option:`lat_percentiles` is
2262 set, total latency (lat) will be reported.
2264 .. option:: cmdprio_class=int[,int] : [io_uring] [libaio]
2266 Set the I/O priority class to use for I/Os that must be issued with
2267 a priority when :option:`cmdprio_percentage` or
2268 :option:`cmdprio_bssplit` is set. If not specified when
2269 :option:`cmdprio_percentage` or :option:`cmdprio_bssplit` is set,
2270 this defaults to the highest priority class. A single value applies
2271 to reads and writes. Comma-separated values may be specified for
2272 reads and writes. See :manpage:`ionice(1)`. See also the
2273 :option:`prioclass` option.
2275 .. option:: cmdprio=int[,int] : [io_uring] [libaio]
2277 Set the I/O priority value to use for I/Os that must be issued with
2278 a priority when :option:`cmdprio_percentage` or
2279 :option:`cmdprio_bssplit` is set. If not specified when
2280 :option:`cmdprio_percentage` or :option:`cmdprio_bssplit` is set,
2282 Linux limits us to a positive value between 0 and 7, with 0 being the
2283 highest. A single value applies to reads and writes. Comma-separated
2284 values may be specified for reads and writes. See :manpage:`ionice(1)`.
2285 Refer to an appropriate manpage for other operating systems since
2286 meaning of priority may differ. See also the :option:`prio` option.
2288 .. option:: cmdprio_bssplit=str[,str] : [io_uring] [libaio]
2290 To get a finer control over I/O priority, this option allows
2291 specifying the percentage of IOs that must have a priority set
2292 depending on the block size of the IO. This option is useful only
2293 when used together with the :option:`bssplit` option, that is,
2294 multiple different block sizes are used for reads and writes.
2296 The first accepted format for this option is the same as the format of
2297 the :option:`bssplit` option:
2299 cmdprio_bssplit=blocksize/percentage:blocksize/percentage
2301 In this case, each entry will use the priority class and priority
2302 level defined by the options :option:`cmdprio_class` and
2303 :option:`cmdprio` respectively.
2305 The second accepted format for this option is:
2307 cmdprio_bssplit=blocksize/percentage/class/level:blocksize/percentage/class/level
2309 In this case, the priority class and priority level is defined inside
2310 each entry. In comparison with the first accepted format, the second
2311 accepted format does not restrict all entries to have the same priority
2312 class and priority level.
2314 For both formats, only the read and write data directions are supported,
2315 values for trim IOs are ignored. This option is mutually exclusive with
2316 the :option:`cmdprio_percentage` option.
2318 .. option:: fixedbufs : [io_uring] [io_uring_cmd]
2320 If fio is asked to do direct IO, then Linux will map pages for each
2321 IO call, and release them when IO is done. If this option is set, the
2322 pages are pre-mapped before IO is started. This eliminates the need to
2323 map and release for each IO. This is more efficient, and reduces the
2326 .. option:: nonvectored=int : [io_uring] [io_uring_cmd]
2328 With this option, fio will use non-vectored read/write commands, where
2329 address must contain the address directly. Default is -1.
2331 .. option:: force_async=int : [io_uring] [io_uring_cmd]
2333 Normal operation for io_uring is to try and issue an sqe as
2334 non-blocking first, and if that fails, execute it in an async manner.
2335 With this option set to N, then every N request fio will ask sqe to
2336 be issued in an async manner. Default is 0.
2338 .. option:: registerfiles : [io_uring] [io_uring_cmd]
2340 With this option, fio registers the set of files being used with the
2341 kernel. This avoids the overhead of managing file counts in the kernel,
2342 making the submission and completion part more lightweight. Required
2343 for the below :option:`sqthread_poll` option.
2345 .. option:: sqthread_poll : [io_uring] [io_uring_cmd] [xnvme]
2347 Normally fio will submit IO by issuing a system call to notify the
2348 kernel of available items in the SQ ring. If this option is set, the
2349 act of submitting IO will be done by a polling thread in the kernel.
2350 This frees up cycles for fio, at the cost of using more CPU in the
2351 system. As submission is just the time it takes to fill in the sqe
2352 entries and any syscall required to wake up the idle kernel thread,
2353 fio will not report submission latencies.
2355 .. option:: sqthread_poll_cpu=int : [io_uring] [io_uring_cmd]
2357 When :option:`sqthread_poll` is set, this option provides a way to
2358 define which CPU should be used for the polling thread.
2360 .. option:: cmd_type=str : [io_uring_cmd]
2362 Specifies the type of uring passthrough command to be used. Supported
2363 value is nvme. Default is nvme.
2367 [io_uring] [io_uring_cmd] [xnvme]
2369 If this option is set, fio will attempt to use polled IO completions.
2370 Normal IO completions generate interrupts to signal the completion of
2371 IO, polled completions do not. Hence they are require active reaping
2372 by the application. The benefits are more efficient IO for high IOPS
2373 scenarios, and lower latencies for low queue depth IO.
2377 Use poll queues. This is incompatible with
2378 :option:`libblkio_wait_mode=eventfd <libblkio_wait_mode>` and
2379 :option:`libblkio_force_enable_completion_eventfd`.
2383 Set RWF_HIPRI on I/O, indicating to the kernel that it's of higher priority
2388 If this option is set, fio will attempt to use polled IO completions.
2389 This will have a similar effect as (io_uring)hipri. Only SCSI READ and
2390 WRITE commands will have the SGV4_FLAG_HIPRI set (not UNMAP (trim) nor
2391 VERIFY). Older versions of the Linux sg driver that do not support
2392 hipri will simply ignore this flag and do normal IO. The Linux SCSI
2393 Low Level Driver (LLD) that "owns" the device also needs to support
2394 hipri (also known as iopoll and mq_poll). The MegaRAID driver is an
2395 example of a SCSI LLD. Default: clear (0) which does normal
2396 (interrupted based) IO.
2398 .. option:: userspace_reap : [libaio]
2400 Normally, with the libaio engine in use, fio will use the
2401 :manpage:`io_getevents(2)` system call to reap newly returned events. With
2402 this flag turned on, the AIO ring will be read directly from user-space to
2403 reap events. The reaping mode is only enabled when polling for a minimum of
2404 0 events (e.g. when :option:`iodepth_batch_complete` `=0`).
2406 .. option:: hipri_percentage : [pvsync2]
2408 When hipri is set this determines the probability of a pvsync2 I/O being high
2409 priority. The default is 100%.
2411 .. option:: nowait=bool : [pvsync2] [libaio] [io_uring] [io_uring_cmd]
2413 By default if a request cannot be executed immediately (e.g. resource starvation,
2414 waiting on locks) it is queued and the initiating process will be blocked until
2415 the required resource becomes free.
2417 This option sets the RWF_NOWAIT flag (supported from the 4.14 Linux kernel) and
2418 the call will return instantly with EAGAIN or a partial result rather than waiting.
2420 It is useful to also use ignore_error=EAGAIN when using this option.
2422 Note: glibc 2.27, 2.28 have a bug in syscall wrappers preadv2, pwritev2.
2423 They return EOPNOTSUP instead of EAGAIN.
2425 For cached I/O, using this option usually means a request operates only with
2426 cached data. Currently the RWF_NOWAIT flag does not supported for cached write.
2428 For direct I/O, requests will only succeed if cache invalidation isn't required,
2429 file blocks are fully allocated and the disk request could be issued immediately.
2431 .. option:: cpuload=int : [cpuio]
2433 Attempt to use the specified percentage of CPU cycles. This is a mandatory
2434 option when using cpuio I/O engine.
2436 .. option:: cpuchunks=int : [cpuio]
2438 Split the load into cycles of the given time. In microseconds.
2440 .. option:: cpumode=str : [cpuio]
2442 Specify how to stress the CPU. It can take these two values:
2445 This is the default where the CPU executes noop instructions.
2447 Replace the default noop instructions loop with a qsort algorithm to
2448 consume more energy.
2450 .. option:: exit_on_io_done=bool : [cpuio]
2452 Detect when I/O threads are done, then exit.
2454 .. option:: namenode=str : [libhdfs]
2456 The hostname or IP address of a HDFS cluster namenode to contact.
2458 .. option:: port=int
2462 The listening port of the HFDS cluster namenode.
2466 The TCP or UDP port to bind to or connect to. If this is used with
2467 :option:`numjobs` to spawn multiple instances of the same job type, then
2468 this will be the starting port number since fio will use a range of
2473 The port to use for RDMA-CM communication. This should be the same value
2474 on the client and the server side.
2476 .. option:: hostname=str : [netsplice] [net] [rdma]
2478 The hostname or IP address to use for TCP, UDP or RDMA-CM based I/O. If the job
2479 is a TCP listener or UDP reader, the hostname is not used and must be omitted
2480 unless it is a valid UDP multicast address.
2482 .. option:: serverip=str : [librpma_*]
2484 The IP address to be used for RDMA-CM based I/O.
2486 .. option:: direct_write_to_pmem=bool : [librpma_*]
2488 Set to 1 only when Direct Write to PMem from the remote host is possible.
2489 Otherwise, set to 0.
2491 .. option:: busy_wait_polling=bool : [librpma_*_server]
2493 Set to 0 to wait for completion instead of busy-wait polling completion.
2496 .. option:: interface=str : [netsplice] [net]
2498 The IP address of the network interface used to send or receive UDP
2501 .. option:: ttl=int : [netsplice] [net]
2503 Time-to-live value for outgoing UDP multicast packets. Default: 1.
2505 .. option:: nodelay=bool : [netsplice] [net]
2507 Set TCP_NODELAY on TCP connections.
2509 .. option:: protocol=str, proto=str : [netsplice] [net]
2511 The network protocol to use. Accepted values are:
2514 Transmission control protocol.
2516 Transmission control protocol V6.
2518 User datagram protocol.
2520 User datagram protocol V6.
2524 When the protocol is TCP or UDP, the port must also be given, as well as the
2525 hostname if the job is a TCP listener or UDP reader. For unix sockets, the
2526 normal :option:`filename` option should be used and the port is invalid.
2528 .. option:: listen : [netsplice] [net]
2530 For TCP network connections, tell fio to listen for incoming connections
2531 rather than initiating an outgoing connection. The :option:`hostname` must
2532 be omitted if this option is used.
2534 .. option:: pingpong : [netsplice] [net]
2536 Normally a network writer will just continue writing data, and a network
2537 reader will just consume packages. If ``pingpong=1`` is set, a writer will
2538 send its normal payload to the reader, then wait for the reader to send the
2539 same payload back. This allows fio to measure network latencies. The
2540 submission and completion latencies then measure local time spent sending or
2541 receiving, and the completion latency measures how long it took for the
2542 other end to receive and send back. For UDP multicast traffic
2543 ``pingpong=1`` should only be set for a single reader when multiple readers
2544 are listening to the same address.
2546 .. option:: window_size : [netsplice] [net]
2548 Set the desired socket buffer size for the connection.
2550 .. option:: mss : [netsplice] [net]
2552 Set the TCP maximum segment size (TCP_MAXSEG).
2554 .. option:: donorname=str : [e4defrag]
2556 File will be used as a block donor (swap extents between files).
2558 .. option:: inplace=int : [e4defrag]
2560 Configure donor file blocks allocation strategy:
2563 Default. Preallocate donor's file on init.
2565 Allocate space immediately inside defragment event, and free right
2568 .. option:: clustername=str : [rbd,rados]
2570 Specifies the name of the Ceph cluster.
2572 .. option:: rbdname=str : [rbd]
2574 Specifies the name of the RBD.
2576 .. option:: clientname=str : [rbd,rados]
2578 Specifies the username (without the 'client.' prefix) used to access the
2579 Ceph cluster. If the *clustername* is specified, the *clientname* shall be
2580 the full *type.id* string. If no type. prefix is given, fio will add
2581 'client.' by default.
2583 .. option:: conf=str : [rados]
2585 Specifies the configuration path of ceph cluster, so conf file does not
2586 have to be /etc/ceph/ceph.conf.
2588 .. option:: busy_poll=bool : [rbd,rados]
2590 Poll store instead of waiting for completion. Usually this provides better
2591 throughput at cost of higher(up to 100%) CPU utilization.
2593 .. option:: touch_objects=bool : [rados]
2595 During initialization, touch (create if do not exist) all objects (files).
2596 Touching all objects affects ceph caches and likely impacts test results.
2599 .. option:: pool=str :
2603 Specifies the name of the Ceph pool containing RBD or RADOS data.
2607 Specify the label or UUID of the DAOS pool to connect to.
2609 .. option:: cont=str : [dfs]
2611 Specify the label or UUID of the DAOS container to open.
2613 .. option:: chunk_size=int
2617 Specify a different chunk size (in bytes) for the dfs file.
2618 Use DAOS container's chunk size by default.
2622 The size of the chunk to use for each file.
2624 .. option:: object_class=str : [dfs]
2626 Specify a different object class for the dfs file.
2627 Use DAOS container's object class by default.
2629 .. option:: skip_bad=bool : [mtd]
2631 Skip operations against known bad blocks.
2633 .. option:: hdfsdirectory : [libhdfs]
2635 libhdfs will create chunk in this HDFS directory.
2637 .. option:: verb=str : [rdma]
2639 The RDMA verb to use on this side of the RDMA ioengine connection. Valid
2640 values are write, read, send and recv. These correspond to the equivalent
2641 RDMA verbs (e.g. write = rdma_write etc.). Note that this only needs to be
2642 specified on the client side of the connection. See the examples folder.
2644 .. option:: bindname=str : [rdma]
2646 The name to use to bind the local RDMA-CM connection to a local RDMA device.
2647 This could be a hostname or an IPv4 or IPv6 address. On the server side this
2648 will be passed into the rdma_bind_addr() function and on the client site it
2649 will be used in the rdma_resolve_add() function. This can be useful when
2650 multiple paths exist between the client and the server or in certain loopback
2653 .. option:: stat_type=str : [filestat]
2655 Specify stat system call type to measure lookup/getattr performance.
2656 Default is **stat** for :manpage:`stat(2)`.
2658 .. option:: readfua=bool : [sg]
2660 With readfua option set to 1, read operations include
2661 the force unit access (fua) flag. Default is 0.
2663 .. option:: writefua=bool : [sg]
2665 With writefua option set to 1, write operations include
2666 the force unit access (fua) flag. Default is 0.
2668 .. option:: sg_write_mode=str : [sg]
2670 Specify the type of write commands to issue. This option can take three values:
2673 This is the default where write opcodes are issued as usual.
2674 **write_and_verify**
2675 Issue WRITE AND VERIFY commands. The BYTCHK bit is set to 0. This
2676 directs the device to carry out a medium verification with no data
2677 comparison. The writefua option is ignored with this selection.
2679 This option is deprecated. Use write_and_verify instead.
2681 Issue WRITE SAME commands. This transfers a single block to the device
2682 and writes this same block of data to a contiguous sequence of LBAs
2683 beginning at the specified offset. fio's block size parameter specifies
2684 the amount of data written with each command. However, the amount of data
2685 actually transferred to the device is equal to the device's block
2686 (sector) size. For a device with 512 byte sectors, blocksize=8k will
2687 write 16 sectors with each command. fio will still generate 8k of data
2688 for each command but only the first 512 bytes will be used and
2689 transferred to the device. The writefua option is ignored with this
2692 This option is deprecated. Use write_same instead.
2694 Issue WRITE SAME(16) commands as above but with the No Data Output
2695 Buffer (NDOB) bit set. No data will be transferred to the device with
2696 this bit set. Data written will be a pre-determined pattern such as
2699 Issue WRITE STREAM(16) commands. Use the **stream_id** option to specify
2700 the stream identifier.
2701 **verify_bytchk_00**
2702 Issue VERIFY commands with BYTCHK set to 00. This directs the
2703 device to carry out a medium verification with no data comparison.
2704 **verify_bytchk_01**
2705 Issue VERIFY commands with BYTCHK set to 01. This directs the device to
2706 compare the data on the device with the data transferred to the device.
2707 **verify_bytchk_11**
2708 Issue VERIFY commands with BYTCHK set to 11. This transfers a
2709 single block to the device and compares the contents of this block with the
2710 data on the device beginning at the specified offset. fio's block size
2711 parameter specifies the total amount of data compared with this command.
2712 However, only one block (sector) worth of data is transferred to the device.
2713 This is similar to the WRITE SAME command except that data is compared instead
2716 .. option:: stream_id=int : [sg]
2718 Set the stream identifier for WRITE STREAM commands. If this is set to 0 (which is not
2719 a valid stream identifier) fio will open a stream and then close it when done. Default
2722 .. option:: http_host=str : [http]
2724 Hostname to connect to. For S3, this could be the bucket hostname.
2725 Default is **localhost**
2727 .. option:: http_user=str : [http]
2729 Username for HTTP authentication.
2731 .. option:: http_pass=str : [http]
2733 Password for HTTP authentication.
2735 .. option:: https=str : [http]
2737 Enable HTTPS instead of http. *on* enables HTTPS; *insecure*
2738 will enable HTTPS, but disable SSL peer verification (use with
2739 caution!). Default is **off**
2741 .. option:: http_mode=str : [http]
2743 Which HTTP access mode to use: *webdav*, *swift*, or *s3*.
2744 Default is **webdav**
2746 .. option:: http_s3_region=str : [http]
2748 The S3 region/zone string.
2749 Default is **us-east-1**
2751 .. option:: http_s3_key=str : [http]
2755 .. option:: http_s3_keyid=str : [http]
2757 The S3 key/access id.
2759 .. option:: http_s3_sse_customer_key=str : [http]
2761 The encryption customer key in SSE server side.
2763 .. option:: http_s3_sse_customer_algorithm=str : [http]
2765 The encryption customer algorithm in SSE server side.
2766 Default is **AES256**
2768 .. option:: http_s3_storage_class=str : [http]
2770 Which storage class to access. User-customizable settings.
2771 Default is **STANDARD**
2773 .. option:: http_swift_auth_token=str : [http]
2775 The Swift auth token. See the example configuration file on how
2778 .. option:: http_verbose=int : [http]
2780 Enable verbose requests from libcurl. Useful for debugging. 1
2781 turns on verbose logging from libcurl, 2 additionally enables
2782 HTTP IO tracing. Default is **0**
2784 .. option:: uri=str : [nbd]
2786 Specify the NBD URI of the server to test. The string
2787 is a standard NBD URI
2788 (see https://github.com/NetworkBlockDevice/nbd/tree/master/doc).
2789 Example URIs: nbd://localhost:10809
2790 nbd+unix:///?socket=/tmp/socket
2791 nbds://tlshost/exportname
2793 .. option:: gpu_dev_ids=str : [libcufile]
2795 Specify the GPU IDs to use with CUDA. This is a colon-separated list of
2796 int. GPUs are assigned to workers roundrobin. Default is 0.
2798 .. option:: cuda_io=str : [libcufile]
2800 Specify the type of I/O to use with CUDA. Default is **cufile**.
2803 Use libcufile and nvidia-fs. This option performs I/O directly
2804 between a GPUDirect Storage filesystem and GPU buffers,
2805 avoiding use of a bounce buffer. If :option:`verify` is set,
2806 cudaMemcpy is used to copy verificaton data between RAM and GPU.
2807 Verification data is copied from RAM to GPU before a write
2808 and from GPU to RAM after a read. :option:`direct` must be 1.
2810 Use POSIX to perform I/O with a RAM buffer, and use cudaMemcpy
2811 to transfer data between RAM and the GPUs. Data is copied from
2812 GPU to RAM before a write and copied from RAM to GPU after a
2813 read. :option:`verify` does not affect use of cudaMemcpy.
2815 .. option:: nfs_url=str : [nfs]
2817 URL in libnfs format, eg nfs://<server|ipv4|ipv6>/path[?arg=val[&arg=val]*]
2818 Refer to the libnfs README for more details.
2820 .. option:: program=str : [exec]
2822 Specify the program to execute.
2824 .. option:: arguments=str : [exec]
2826 Specify arguments to pass to program.
2827 Some special variables can be expanded to pass fio's job details to the program.
2830 Replaced by the duration of the job in seconds.
2832 Replaced by the name of the job.
2834 .. option:: grace_time=int : [exec]
2836 Specify the time between the SIGTERM and SIGKILL signals. Default is 1 second.
2838 .. option:: std_redirect=bool : [exec]
2840 If set, stdout and stderr streams are redirected to files named from the job name. Default is true.
2842 .. option:: xnvme_async=str : [xnvme]
2844 Select the xnvme async command interface. This can take these values.
2847 This is default and use to emulate asynchronous I/O by using a
2848 single thread to create a queue pair on top of a synchronous
2849 I/O interface using the NVMe driver IOCTL.
2851 Emulate an asynchronous I/O interface with a pool of userspace
2852 threads on top of a synchronous I/O interface using the NVMe
2853 driver IOCTL. By default four threads are used.
2855 Linux native asynchronous I/O interface which supports both
2856 direct and buffered I/O.
2858 Fast Linux native asynchronous I/O interface for NVMe pass
2859 through commands. This only works with NVMe character device
2862 Use Linux aio for Asynchronous I/O.
2864 Use the posix asynchronous I/O interface to perform one or
2865 more I/O operations asynchronously.
2867 Use the user-space VFIO-based backend, implemented using
2868 libvfn instead of SPDK.
2870 Do not transfer any data; just pretend to. This is mainly used
2871 for introspective performance evaluation.
2873 .. option:: xnvme_sync=str : [xnvme]
2875 Select the xnvme synchronous command interface. This can take these values.
2878 This is default and uses Linux NVMe Driver ioctl() for
2881 This supports regular as well as vectored pread() and pwrite()
2884 This is the same as psync except that it also supports zone
2885 management commands using Linux block layer IOCTLs.
2887 .. option:: xnvme_admin=str : [xnvme]
2889 Select the xnvme admin command interface. This can take these values.
2892 This is default and uses linux NVMe Driver ioctl() for admin
2895 Use Linux Block Layer ioctl() and sysfs for admin commands.
2897 .. option:: xnvme_dev_nsid=int : [xnvme]
2899 xnvme namespace identifier for userspace NVMe driver, SPDK or vfio.
2901 .. option:: xnvme_dev_subnqn=str : [xnvme]
2903 Sets the subsystem NQN for fabrics. This is for xNVMe to utilize a
2904 fabrics target with multiple systems.
2906 .. option:: xnvme_mem=str : [xnvme]
2908 Select the xnvme memory backend. This can take these values.
2911 This is the default posix memory backend for linux NVMe driver.
2913 Use hugepages, instead of existing posix memory backend. The
2914 memory backend uses hugetlbfs. This require users to allocate
2915 hugepages, mount hugetlbfs and set an enviornment variable for
2918 Uses SPDK's memory allocator.
2920 Uses libvfn's memory allocator. This also specifies the use
2921 of libvfn backend instead of SPDK.
2923 .. option:: xnvme_iovec=int : [xnvme]
2925 If this option is set. xnvme will use vectored read/write commands.
2927 .. option:: libblkio_driver=str : [libblkio]
2929 The libblkio *driver* to use. Different drivers access devices through
2930 different underlying interfaces. Available drivers depend on the
2931 libblkio version in use and are listed at
2932 https://libblkio.gitlab.io/libblkio/blkio.html#drivers
2934 .. option:: libblkio_path=str : [libblkio]
2936 Sets the value of the driver-specific "path" property before connecting
2937 the libblkio instance, which identifies the target device or file on
2938 which to perform I/O. Its exact semantics are driver-dependent and not
2939 all drivers may support it; see
2940 https://libblkio.gitlab.io/libblkio/blkio.html#drivers
2942 .. option:: libblkio_pre_connect_props=str : [libblkio]
2944 A colon-separated list of additional libblkio properties to be set after
2945 creating but before connecting the libblkio instance. Each property must
2946 have the format ``<name>=<value>``. Colons can be escaped as ``\:``.
2947 These are set after the engine sets any other properties, so those can
2948 be overriden. Available properties depend on the libblkio version in use
2950 https://libblkio.gitlab.io/libblkio/blkio.html#properties
2952 .. option:: libblkio_num_entries=int : [libblkio]
2954 Sets the value of the driver-specific "num-entries" property before
2955 starting the libblkio instance. Its exact semantics are driver-dependent
2956 and not all drivers may support it; see
2957 https://libblkio.gitlab.io/libblkio/blkio.html#drivers
2959 .. option:: libblkio_queue_size=int : [libblkio]
2961 Sets the value of the driver-specific "queue-size" property before
2962 starting the libblkio instance. Its exact semantics are driver-dependent
2963 and not all drivers may support it; see
2964 https://libblkio.gitlab.io/libblkio/blkio.html#drivers
2966 .. option:: libblkio_pre_start_props=str : [libblkio]
2968 A colon-separated list of additional libblkio properties to be set after
2969 connecting but before starting the libblkio instance. Each property must
2970 have the format ``<name>=<value>``. Colons can be escaped as ``\:``.
2971 These are set after the engine sets any other properties, so those can
2972 be overriden. Available properties depend on the libblkio version in use
2974 https://libblkio.gitlab.io/libblkio/blkio.html#properties
2976 .. option:: libblkio_vectored : [libblkio]
2978 Submit vectored read and write requests.
2980 .. option:: libblkio_write_zeroes_on_trim : [libblkio]
2982 Submit trims as "write zeroes" requests instead of discard requests.
2984 .. option:: libblkio_wait_mode=str : [libblkio]
2986 How to wait for completions:
2989 Use a blocking call to ``blkioq_do_io()``.
2991 Use a blocking call to ``read()`` on the completion eventfd.
2993 Use a busy loop with a non-blocking call to ``blkioq_do_io()``.
2995 .. option:: libblkio_force_enable_completion_eventfd : [libblkio]
2997 Enable the queue's completion eventfd even when unused. This may impact
2998 performance. The default is to enable it only if
2999 :option:`libblkio_wait_mode=eventfd <libblkio_wait_mode>`.
3004 .. option:: iodepth=int
3006 Number of I/O units to keep in flight against the file. Note that
3007 increasing *iodepth* beyond 1 will not affect synchronous ioengines (except
3008 for small degrees when :option:`verify_async` is in use). Even async
3009 engines may impose OS restrictions causing the desired depth not to be
3010 achieved. This may happen on Linux when using libaio and not setting
3011 :option:`direct`\=1, since buffered I/O is not async on that OS. Keep an
3012 eye on the I/O depth distribution in the fio output to verify that the
3013 achieved depth is as expected. Default: 1.
3015 .. option:: iodepth_batch_submit=int, iodepth_batch=int
3017 This defines how many pieces of I/O to submit at once. It defaults to 1
3018 which means that we submit each I/O as soon as it is available, but can be
3019 raised to submit bigger batches of I/O at the time. If it is set to 0 the
3020 :option:`iodepth` value will be used.
3022 .. option:: iodepth_batch_complete_min=int, iodepth_batch_complete=int
3024 This defines how many pieces of I/O to retrieve at once. It defaults to 1
3025 which means that we'll ask for a minimum of 1 I/O in the retrieval process
3026 from the kernel. The I/O retrieval will go on until we hit the limit set by
3027 :option:`iodepth_low`. If this variable is set to 0, then fio will always
3028 check for completed events before queuing more I/O. This helps reduce I/O
3029 latency, at the cost of more retrieval system calls.
3031 .. option:: iodepth_batch_complete_max=int
3033 This defines maximum pieces of I/O to retrieve at once. This variable should
3034 be used along with :option:`iodepth_batch_complete_min`\=int variable,
3035 specifying the range of min and max amount of I/O which should be
3036 retrieved. By default it is equal to the :option:`iodepth_batch_complete_min`
3041 iodepth_batch_complete_min=1
3042 iodepth_batch_complete_max=<iodepth>
3044 which means that we will retrieve at least 1 I/O and up to the whole
3045 submitted queue depth. If none of I/O has been completed yet, we will wait.
3049 iodepth_batch_complete_min=0
3050 iodepth_batch_complete_max=<iodepth>
3052 which means that we can retrieve up to the whole submitted queue depth, but
3053 if none of I/O has been completed yet, we will NOT wait and immediately exit
3054 the system call. In this example we simply do polling.
3056 .. option:: iodepth_low=int
3058 The low water mark indicating when to start filling the queue
3059 again. Defaults to the same as :option:`iodepth`, meaning that fio will
3060 attempt to keep the queue full at all times. If :option:`iodepth` is set to
3061 e.g. 16 and *iodepth_low* is set to 4, then after fio has filled the queue of
3062 16 requests, it will let the depth drain down to 4 before starting to fill
3065 .. option:: serialize_overlap=bool
3067 Serialize in-flight I/Os that might otherwise cause or suffer from data races.
3068 When two or more I/Os are submitted simultaneously, there is no guarantee that
3069 the I/Os will be processed or completed in the submitted order. Further, if
3070 two or more of those I/Os are writes, any overlapping region between them can
3071 become indeterminate/undefined on certain storage. These issues can cause
3072 verification to fail erratically when at least one of the racing I/Os is
3073 changing data and the overlapping region has a non-zero size. Setting
3074 ``serialize_overlap`` tells fio to avoid provoking this behavior by explicitly
3075 serializing in-flight I/Os that have a non-zero overlap. Note that setting
3076 this option can reduce both performance and the :option:`iodepth` achieved.
3078 This option only applies to I/Os issued for a single job except when it is
3079 enabled along with :option:`io_submit_mode`\=offload. In offload mode, fio
3080 will check for overlap among all I/Os submitted by offload jobs with :option:`serialize_overlap`
3085 .. option:: io_submit_mode=str
3087 This option controls how fio submits the I/O to the I/O engine. The default
3088 is `inline`, which means that the fio job threads submit and reap I/O
3089 directly. If set to `offload`, the job threads will offload I/O submission
3090 to a dedicated pool of I/O threads. This requires some coordination and thus
3091 has a bit of extra overhead, especially for lower queue depth I/O where it
3092 can increase latencies. The benefit is that fio can manage submission rates
3093 independently of the device completion rates. This avoids skewed latency
3094 reporting if I/O gets backed up on the device side (the coordinated omission
3095 problem). Note that this option cannot reliably be used with async IO
3102 .. option:: thinktime=time
3104 Stall the job for the specified period of time after an I/O has completed before issuing the
3105 next. May be used to simulate processing being done by an application.
3106 When the unit is omitted, the value is interpreted in microseconds. See
3107 :option:`thinktime_blocks`, :option:`thinktime_iotime` and :option:`thinktime_spin`.
3109 .. option:: thinktime_spin=time
3111 Only valid if :option:`thinktime` is set - pretend to spend CPU time doing
3112 something with the data received, before falling back to sleeping for the
3113 rest of the period specified by :option:`thinktime`. When the unit is
3114 omitted, the value is interpreted in microseconds.
3116 .. option:: thinktime_blocks=int
3118 Only valid if :option:`thinktime` is set - control how many blocks to issue,
3119 before waiting :option:`thinktime` usecs. If not set, defaults to 1 which will make
3120 fio wait :option:`thinktime` usecs after every block. This effectively makes any
3121 queue depth setting redundant, since no more than 1 I/O will be queued
3122 before we have to complete it and do our :option:`thinktime`. In other words, this
3123 setting effectively caps the queue depth if the latter is larger.
3125 .. option:: thinktime_blocks_type=str
3127 Only valid if :option:`thinktime` is set - control how :option:`thinktime_blocks`
3128 triggers. The default is `complete`, which triggers thinktime when fio completes
3129 :option:`thinktime_blocks` blocks. If this is set to `issue`, then the trigger happens
3132 .. option:: thinktime_iotime=time
3134 Only valid if :option:`thinktime` is set - control :option:`thinktime`
3135 interval by time. The :option:`thinktime` stall is repeated after IOs
3136 are executed for :option:`thinktime_iotime`. For example,
3137 ``--thinktime_iotime=9s --thinktime=1s`` repeat 10-second cycle with IOs
3138 for 9 seconds and stall for 1 second. When the unit is omitted,
3139 :option:`thinktime_iotime` is interpreted as a number of seconds. If
3140 this option is used together with :option:`thinktime_blocks`, the
3141 :option:`thinktime` stall is repeated after :option:`thinktime_iotime`
3142 or after :option:`thinktime_blocks` IOs, whichever happens first.
3144 .. option:: rate=int[,int][,int]
3146 Cap the bandwidth used by this job. The number is in bytes/sec, the normal
3147 suffix rules apply. Comma-separated values may be specified for reads,
3148 writes, and trims as described in :option:`blocksize`.
3150 For example, using `rate=1m,500k` would limit reads to 1MiB/sec and writes to
3151 500KiB/sec. Capping only reads or writes can be done with `rate=,500k` or
3152 `rate=500k,` where the former will only limit writes (to 500KiB/sec) and the
3153 latter will only limit reads.
3155 .. option:: rate_min=int[,int][,int]
3157 Tell fio to do whatever it can to maintain at least this bandwidth. Failing
3158 to meet this requirement will cause the job to exit. Comma-separated values
3159 may be specified for reads, writes, and trims as described in
3160 :option:`blocksize`.
3162 .. option:: rate_iops=int[,int][,int]
3164 Cap the bandwidth to this number of IOPS. Basically the same as
3165 :option:`rate`, just specified independently of bandwidth. If the job is
3166 given a block size range instead of a fixed value, the smallest block size
3167 is used as the metric. Comma-separated values may be specified for reads,
3168 writes, and trims as described in :option:`blocksize`.
3170 .. option:: rate_iops_min=int[,int][,int]
3172 If fio doesn't meet this rate of I/O, it will cause the job to exit.
3173 Comma-separated values may be specified for reads, writes, and trims as
3174 described in :option:`blocksize`.
3176 .. option:: rate_process=str
3178 This option controls how fio manages rated I/O submissions. The default is
3179 `linear`, which submits I/O in a linear fashion with fixed delays between
3180 I/Os that gets adjusted based on I/O completion rates. If this is set to
3181 `poisson`, fio will submit I/O based on a more real world random request
3182 flow, known as the Poisson process
3183 (https://en.wikipedia.org/wiki/Poisson_point_process). The lambda will be
3184 10^6 / IOPS for the given workload.
3186 .. option:: rate_ignore_thinktime=bool
3188 By default, fio will attempt to catch up to the specified rate setting,
3189 if any kind of thinktime setting was used. If this option is set, then
3190 fio will ignore the thinktime and continue doing IO at the specified
3191 rate, instead of entering a catch-up mode after thinktime is done.
3197 .. option:: latency_target=time
3199 If set, fio will attempt to find the max performance point that the given
3200 workload will run at while maintaining a latency below this target. When
3201 the unit is omitted, the value is interpreted in microseconds. See
3202 :option:`latency_window` and :option:`latency_percentile`.
3204 .. option:: latency_window=time
3206 Used with :option:`latency_target` to specify the sample window that the job
3207 is run at varying queue depths to test the performance. When the unit is
3208 omitted, the value is interpreted in microseconds.
3210 .. option:: latency_percentile=float
3212 The percentage of I/Os that must fall within the criteria specified by
3213 :option:`latency_target` and :option:`latency_window`. If not set, this
3214 defaults to 100.0, meaning that all I/Os must be equal or below to the value
3215 set by :option:`latency_target`.
3217 .. option:: latency_run=bool
3219 Used with :option:`latency_target`. If false (default), fio will find
3220 the highest queue depth that meets :option:`latency_target` and exit. If
3221 true, fio will continue running and try to meet :option:`latency_target`
3222 by adjusting queue depth.
3224 .. option:: max_latency=time[,time][,time]
3226 If set, fio will exit the job with an ETIMEDOUT error if it exceeds this
3227 maximum latency. When the unit is omitted, the value is interpreted in
3228 microseconds. Comma-separated values may be specified for reads, writes,
3229 and trims as described in :option:`blocksize`.
3231 .. option:: rate_cycle=int
3233 Average bandwidth for :option:`rate` and :option:`rate_min` over this number
3234 of milliseconds. Defaults to 1000.
3240 .. option:: write_iolog=str
3242 Write the issued I/O patterns to the specified file. See
3243 :option:`read_iolog`. Specify a separate file for each job, otherwise the
3244 iologs will be interspersed and the file may be corrupt. This file will
3245 be opened in append mode.
3247 .. option:: read_iolog=str
3249 Open an iolog with the specified filename and replay the I/O patterns it
3250 contains. This can be used to store a workload and replay it sometime
3251 later. The iolog given may also be a blktrace binary file, which allows fio
3252 to replay a workload captured by :command:`blktrace`. See
3253 :manpage:`blktrace(8)` for how to capture such logging data. For blktrace
3254 replay, the file needs to be turned into a blkparse binary data file first
3255 (``blkparse <device> -o /dev/null -d file_for_fio.bin``).
3256 You can specify a number of files by separating the names with a ':'
3257 character. See the :option:`filename` option for information on how to
3258 escape ':' characters within the file names. These files will
3259 be sequentially assigned to job clones created by :option:`numjobs`.
3260 '-' is a reserved name, meaning read from stdin, notably if
3261 :option:`filename` is set to '-' which means stdin as well, then
3262 this flag can't be set to '-'.
3264 .. option:: read_iolog_chunked=bool
3266 Determines how iolog is read. If false(default) entire :option:`read_iolog`
3267 will be read at once. If selected true, input from iolog will be read
3268 gradually. Useful when iolog is very large, or it is generated.
3270 .. option:: merge_blktrace_file=str
3272 When specified, rather than replaying the logs passed to :option:`read_iolog`,
3273 the logs go through a merge phase which aggregates them into a single
3274 blktrace. The resulting file is then passed on as the :option:`read_iolog`
3275 parameter. The intention here is to make the order of events consistent.
3276 This limits the influence of the scheduler compared to replaying multiple
3277 blktraces via concurrent jobs.
3279 .. option:: merge_blktrace_scalars=float_list
3281 This is a percentage based option that is index paired with the list of
3282 files passed to :option:`read_iolog`. When merging is performed, scale
3283 the time of each event by the corresponding amount. For example,
3284 ``--merge_blktrace_scalars="50:100"`` runs the first trace in halftime
3285 and the second trace in realtime. This knob is separately tunable from
3286 :option:`replay_time_scale` which scales the trace during runtime and
3287 does not change the output of the merge unlike this option.
3289 .. option:: merge_blktrace_iters=float_list
3291 This is a whole number option that is index paired with the list of files
3292 passed to :option:`read_iolog`. When merging is performed, run each trace
3293 for the specified number of iterations. For example,
3294 ``--merge_blktrace_iters="2:1"`` runs the first trace for two iterations
3295 and the second trace for one iteration.
3297 .. option:: replay_no_stall=bool
3299 When replaying I/O with :option:`read_iolog` the default behavior is to
3300 attempt to respect the timestamps within the log and replay them with the
3301 appropriate delay between IOPS. By setting this variable fio will not
3302 respect the timestamps and attempt to replay them as fast as possible while
3303 still respecting ordering. The result is the same I/O pattern to a given
3304 device, but different timings.
3306 .. option:: replay_time_scale=int
3308 When replaying I/O with :option:`read_iolog`, fio will honor the
3309 original timing in the trace. With this option, it's possible to scale
3310 the time. It's a percentage option, if set to 50 it means run at 50%
3311 the original IO rate in the trace. If set to 200, run at twice the
3312 original IO rate. Defaults to 100.
3314 .. option:: replay_redirect=str
3316 While replaying I/O patterns using :option:`read_iolog` the default behavior
3317 is to replay the IOPS onto the major/minor device that each IOP was recorded
3318 from. This is sometimes undesirable because on a different machine those
3319 major/minor numbers can map to a different device. Changing hardware on the
3320 same system can also result in a different major/minor mapping.
3321 ``replay_redirect`` causes all I/Os to be replayed onto the single specified
3322 device regardless of the device it was recorded
3323 from. i.e. :option:`replay_redirect`\= :file:`/dev/sdc` would cause all I/O
3324 in the blktrace or iolog to be replayed onto :file:`/dev/sdc`. This means
3325 multiple devices will be replayed onto a single device, if the trace
3326 contains multiple devices. If you want multiple devices to be replayed
3327 concurrently to multiple redirected devices you must blkparse your trace
3328 into separate traces and replay them with independent fio invocations.
3329 Unfortunately this also breaks the strict time ordering between multiple
3332 .. option:: replay_align=int
3334 Force alignment of the byte offsets in a trace to this value. The value
3335 must be a power of 2.
3337 .. option:: replay_scale=int
3339 Scale byte offsets down by this factor when replaying traces. Should most
3340 likely use :option:`replay_align` as well.
3342 .. option:: replay_skip=str
3344 Sometimes it's useful to skip certain IO types in a replay trace.
3345 This could be, for instance, eliminating the writes in the trace.
3346 Or not replaying the trims/discards, if you are redirecting to
3347 a device that doesn't support them. This option takes a comma
3348 separated list of read, write, trim, sync.
3351 Threads, processes and job synchronization
3352 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3356 Fio defaults to creating jobs by using fork, however if this option is
3357 given, fio will create jobs by using POSIX Threads' function
3358 :manpage:`pthread_create(3)` to create threads instead.
3360 .. option:: wait_for=str
3362 If set, the current job won't be started until all workers of the specified
3363 waitee job are done.
3365 ``wait_for`` operates on the job name basis, so there are a few
3366 limitations. First, the waitee must be defined prior to the waiter job
3367 (meaning no forward references). Second, if a job is being referenced as a
3368 waitee, it must have a unique name (no duplicate waitees).
3370 .. option:: nice=int
3372 Run the job with the given nice value. See man :manpage:`nice(2)`.
3374 On Windows, values less than -15 set the process class to "High"; -1 through
3375 -15 set "Above Normal"; 1 through 15 "Below Normal"; and above 15 "Idle"
3378 .. option:: prio=int
3380 Set the I/O priority value of this job. Linux limits us to a positive value
3381 between 0 and 7, with 0 being the highest. See man
3382 :manpage:`ionice(1)`. Refer to an appropriate manpage for other operating
3383 systems since meaning of priority may differ. For per-command priority
3384 setting, see I/O engine specific :option:`cmdprio_percentage` and
3385 :option:`cmdprio` options.
3387 .. option:: prioclass=int
3389 Set the I/O priority class. See man :manpage:`ionice(1)`. For per-command
3390 priority setting, see I/O engine specific :option:`cmdprio_percentage`
3391 and :option:`cmdprio_class` options.
3393 .. option:: cpus_allowed=str
3395 Controls the same options as :option:`cpumask`, but accepts a textual
3396 specification of the permitted CPUs instead and CPUs are indexed from 0. So
3397 to use CPUs 0 and 5 you would specify ``cpus_allowed=0,5``. This option also
3398 allows a range of CPUs to be specified -- say you wanted a binding to CPUs
3399 0, 5, and 8 to 15, you would set ``cpus_allowed=0,5,8-15``.
3401 On Windows, when ``cpus_allowed`` is unset only CPUs from fio's current
3402 processor group will be used and affinity settings are inherited from the
3403 system. An fio build configured to target Windows 7 makes options that set
3404 CPUs processor group aware and values will set both the processor group
3405 and a CPU from within that group. For example, on a system where processor
3406 group 0 has 40 CPUs and processor group 1 has 32 CPUs, ``cpus_allowed``
3407 values between 0 and 39 will bind CPUs from processor group 0 and
3408 ``cpus_allowed`` values between 40 and 71 will bind CPUs from processor
3409 group 1. When using ``cpus_allowed_policy=shared`` all CPUs specified by a
3410 single ``cpus_allowed`` option must be from the same processor group. For
3411 Windows fio builds not built for Windows 7, CPUs will only be selected from
3412 (and be relative to) whatever processor group fio happens to be running in
3413 and CPUs from other processor groups cannot be used.
3415 .. option:: cpus_allowed_policy=str
3417 Set the policy of how fio distributes the CPUs specified by
3418 :option:`cpus_allowed` or :option:`cpumask`. Two policies are supported:
3421 All jobs will share the CPU set specified.
3423 Each job will get a unique CPU from the CPU set.
3425 **shared** is the default behavior, if the option isn't specified. If
3426 **split** is specified, then fio will assign one cpu per job. If not
3427 enough CPUs are given for the jobs listed, then fio will roundrobin the CPUs
3430 .. option:: cpumask=int
3432 Set the CPU affinity of this job. The parameter given is a bit mask of
3433 allowed CPUs the job may run on. So if you want the allowed CPUs to be 1
3434 and 5, you would pass the decimal value of (1 << 1 | 1 << 5), or 34. See man
3435 :manpage:`sched_setaffinity(2)`. This may not work on all supported
3436 operating systems or kernel versions. This option doesn't work well for a
3437 higher CPU count than what you can store in an integer mask, so it can only
3438 control cpus 1-32. For boxes with larger CPU counts, use
3439 :option:`cpus_allowed`.
3441 .. option:: numa_cpu_nodes=str
3443 Set this job running on specified NUMA nodes' CPUs. The arguments allow
3444 comma delimited list of cpu numbers, A-B ranges, or `all`. Note, to enable
3445 NUMA options support, fio must be built on a system with libnuma-dev(el)
3448 .. option:: numa_mem_policy=str
3450 Set this job's memory policy and corresponding NUMA nodes. Format of the
3455 ``mode`` is one of the following memory policies: ``default``, ``prefer``,
3456 ``bind``, ``interleave`` or ``local``. For ``default`` and ``local`` memory
3457 policies, no node needs to be specified. For ``prefer``, only one node is
3458 allowed. For ``bind`` and ``interleave`` the ``nodelist`` may be as
3459 follows: a comma delimited list of numbers, A-B ranges, or `all`.
3461 .. option:: cgroup=str
3463 Add job to this control group. If it doesn't exist, it will be created. The
3464 system must have a mounted cgroup blkio mount point for this to work. If
3465 your system doesn't have it mounted, you can do so with::
3467 # mount -t cgroup -o blkio none /cgroup
3469 .. option:: cgroup_weight=int
3471 Set the weight of the cgroup to this value. See the documentation that comes
3472 with the kernel, allowed values are in the range of 100..1000.
3474 .. option:: cgroup_nodelete=bool
3476 Normally fio will delete the cgroups it has created after the job
3477 completion. To override this behavior and to leave cgroups around after the
3478 job completion, set ``cgroup_nodelete=1``. This can be useful if one wants
3479 to inspect various cgroup files after job completion. Default: false.
3481 .. option:: flow_id=int
3483 The ID of the flow. If not specified, it defaults to being a global
3484 flow. See :option:`flow`.
3486 .. option:: flow=int
3488 Weight in token-based flow control. If this value is used, then fio
3489 regulates the activity between two or more jobs sharing the same
3490 flow_id. Fio attempts to keep each job activity proportional to other
3491 jobs' activities in the same flow_id group, with respect to requested
3492 weight per job. That is, if one job has `flow=3', another job has
3493 `flow=2' and another with `flow=1`, then there will be a roughly 3:2:1
3494 ratio in how much one runs vs the others.
3496 .. option:: flow_sleep=int
3498 The period of time, in microseconds, to wait after the flow counter
3499 has exceeded its proportion before retrying operations.
3501 .. option:: stonewall, wait_for_previous
3503 Wait for preceding jobs in the job file to exit, before starting this
3504 one. Can be used to insert serialization points in the job file. A stone
3505 wall also implies starting a new reporting group, see
3506 :option:`group_reporting`.
3510 By default, fio will continue running all other jobs when one job finishes.
3511 Sometimes this is not the desired action. Setting ``exitall`` will instead
3512 make fio terminate all jobs in the same group, as soon as one job of that
3515 .. option:: exit_what=str
3517 By default, fio will continue running all other jobs when one job finishes.
3518 Sometimes this is not the desired action. Setting ``exitall`` will
3519 instead make fio terminate all jobs in the same group. The option
3520 ``exit_what`` allows to control which jobs get terminated when ``exitall`` is
3521 enabled. The default is ``group`` and does not change the behaviour of
3522 ``exitall``. The setting ``all`` terminates all jobs. The setting ``stonewall``
3523 terminates all currently running jobs across all groups and continues execution
3524 with the next stonewalled group.
3526 .. option:: exec_prerun=str
3528 Before running this job, issue the command specified through
3529 :manpage:`system(3)`. Output is redirected in a file called
3530 :file:`jobname.prerun.txt`.
3532 .. option:: exec_postrun=str
3534 After the job completes, issue the command specified though
3535 :manpage:`system(3)`. Output is redirected in a file called
3536 :file:`jobname.postrun.txt`.
3540 Instead of running as the invoking user, set the user ID to this value
3541 before the thread/process does any work.
3545 Set group ID, see :option:`uid`.
3551 .. option:: verify_only
3553 Do not perform specified workload, only verify data still matches previous
3554 invocation of this workload. This option allows one to check data multiple
3555 times at a later date without overwriting it. This option makes sense only
3556 for workloads that write data, and does not support workloads with the
3557 :option:`time_based` option set.
3559 .. option:: do_verify=bool
3561 Run the verify phase after a write phase. Only valid if :option:`verify` is
3564 .. option:: verify=str
3566 If writing to a file, fio can verify the file contents after each iteration
3567 of the job. Each verification method also implies verification of special
3568 header, which is written to the beginning of each block. This header also
3569 includes meta information, like offset of the block, block number, timestamp
3570 when block was written, etc. :option:`verify` can be combined with
3571 :option:`verify_pattern` option. The allowed values are:
3574 Use an md5 sum of the data area and store it in the header of
3578 Use an experimental crc64 sum of the data area and store it in the
3579 header of each block.
3582 Use a crc32c sum of the data area and store it in the header of
3583 each block. This will automatically use hardware acceleration
3584 (e.g. SSE4.2 on an x86 or CRC crypto extensions on ARM64) but will
3585 fall back to software crc32c if none is found. Generally the
3586 fastest checksum fio supports when hardware accelerated.
3592 Use a crc32 sum of the data area and store it in the header of each
3596 Use a crc16 sum of the data area and store it in the header of each
3600 Use a crc7 sum of the data area and store it in the header of each
3604 Use xxhash as the checksum function. Generally the fastest software
3605 checksum that fio supports.
3608 Use sha512 as the checksum function.
3611 Use sha256 as the checksum function.
3614 Use optimized sha1 as the checksum function.
3617 Use optimized sha3-224 as the checksum function.
3620 Use optimized sha3-256 as the checksum function.
3623 Use optimized sha3-384 as the checksum function.
3626 Use optimized sha3-512 as the checksum function.
3629 This option is deprecated, since now meta information is included in
3630 generic verification header and meta verification happens by
3631 default. For detailed information see the description of the
3632 :option:`verify` setting. This option is kept because of
3633 compatibility's sake with old configurations. Do not use it.
3636 Verify a strict pattern. Normally fio includes a header with some
3637 basic information and checksumming, but if this option is set, only
3638 the specific pattern set with :option:`verify_pattern` is verified.
3641 Only pretend to verify. Useful for testing internals with
3642 :option:`ioengine`\=null, not for much else.
3644 This option can be used for repeated burn-in tests of a system to make sure
3645 that the written data is also correctly read back. If the data direction
3646 given is a read or random read, fio will assume that it should verify a
3647 previously written file. If the data direction includes any form of write,
3648 the verify will be of the newly written data.
3650 To avoid false verification errors, do not use the norandommap option when
3651 verifying data with async I/O engines and I/O depths > 1. Or use the
3652 norandommap and the lfsr random generator together to avoid writing to the
3653 same offset with multiple outstanding I/Os.
3655 .. option:: verify_offset=int
3657 Swap the verification header with data somewhere else in the block before
3658 writing. It is swapped back before verifying.
3660 .. option:: verify_interval=int
3662 Write the verification header at a finer granularity than the
3663 :option:`blocksize`. It will be written for chunks the size of
3664 ``verify_interval``. :option:`blocksize` should divide this evenly.
3666 .. option:: verify_pattern=str
3668 If set, fio will fill the I/O buffers with this pattern. Fio defaults to
3669 filling with totally random bytes, but sometimes it's interesting to fill
3670 with a known pattern for I/O verification purposes. Depending on the width
3671 of the pattern, fio will fill 1/2/3/4 bytes of the buffer at the time (it can
3672 be either a decimal or a hex number). The ``verify_pattern`` if larger than
3673 a 32-bit quantity has to be a hex number that starts with either "0x" or
3674 "0X". Use with :option:`verify`. Also, ``verify_pattern`` supports %o
3675 format, which means that for each block offset will be written and then
3676 verified back, e.g.::
3680 Or use combination of everything::
3682 verify_pattern=0xff%o"abcd"-12
3684 .. option:: verify_fatal=bool
3686 Normally fio will keep checking the entire contents before quitting on a
3687 block verification failure. If this option is set, fio will exit the job on
3688 the first observed failure. Default: false.
3690 .. option:: verify_dump=bool
3692 If set, dump the contents of both the original data block and the data block
3693 we read off disk to files. This allows later analysis to inspect just what
3694 kind of data corruption occurred. Off by default.
3696 .. option:: verify_async=int
3698 Fio will normally verify I/O inline from the submitting thread. This option
3699 takes an integer describing how many async offload threads to create for I/O
3700 verification instead, causing fio to offload the duty of verifying I/O
3701 contents to one or more separate threads. If using this offload option, even
3702 sync I/O engines can benefit from using an :option:`iodepth` setting higher
3703 than 1, as it allows them to have I/O in flight while verifies are running.
3704 Defaults to 0 async threads, i.e. verification is not asynchronous.
3706 .. option:: verify_async_cpus=str
3708 Tell fio to set the given CPU affinity on the async I/O verification
3709 threads. See :option:`cpus_allowed` for the format used.
3711 .. option:: verify_backlog=int
3713 Fio will normally verify the written contents of a job that utilizes verify
3714 once that job has completed. In other words, everything is written then
3715 everything is read back and verified. You may want to verify continually
3716 instead for a variety of reasons. Fio stores the meta data associated with
3717 an I/O block in memory, so for large verify workloads, quite a bit of memory
3718 would be used up holding this meta data. If this option is enabled, fio will
3719 write only N blocks before verifying these blocks.
3721 .. option:: verify_backlog_batch=int
3723 Control how many blocks fio will verify if :option:`verify_backlog` is
3724 set. If not set, will default to the value of :option:`verify_backlog`
3725 (meaning the entire queue is read back and verified). If
3726 ``verify_backlog_batch`` is less than :option:`verify_backlog` then not all
3727 blocks will be verified, if ``verify_backlog_batch`` is larger than
3728 :option:`verify_backlog`, some blocks will be verified more than once.
3730 .. option:: verify_state_save=bool
3732 When a job exits during the write phase of a verify workload, save its
3733 current state. This allows fio to replay up until that point, if the verify
3734 state is loaded for the verify read phase. The format of the filename is,
3737 <type>-<jobname>-<jobindex>-verify.state.
3739 <type> is "local" for a local run, "sock" for a client/server socket
3740 connection, and "ip" (192.168.0.1, for instance) for a networked
3741 client/server connection. Defaults to true.
3743 .. option:: verify_state_load=bool
3745 If a verify termination trigger was used, fio stores the current write state
3746 of each thread. This can be used at verification time so that fio knows how
3747 far it should verify. Without this information, fio will run a full
3748 verification pass, according to the settings in the job file used. Default
3751 .. option:: trim_percentage=int
3753 Number of verify blocks to discard/trim.
3755 .. option:: trim_verify_zero=bool
3757 Verify that trim/discarded blocks are returned as zeros.
3759 .. option:: trim_backlog=int
3761 Trim after this number of blocks are written.
3763 .. option:: trim_backlog_batch=int
3765 Trim this number of I/O blocks.
3767 .. option:: experimental_verify=bool
3769 Enable experimental verification. Standard verify records I/O metadata
3770 for later use during the verification phase. Experimental verify
3771 instead resets the file after the write phase and then replays I/Os for
3772 the verification phase.
3777 .. option:: steadystate=str:float, ss=str:float
3779 Define the criterion and limit for assessing steady state performance. The
3780 first parameter designates the criterion whereas the second parameter sets
3781 the threshold. When the criterion falls below the threshold for the
3782 specified duration, the job will stop. For example, `iops_slope:0.1%` will
3783 direct fio to terminate the job when the least squares regression slope
3784 falls below 0.1% of the mean IOPS. If :option:`group_reporting` is enabled
3785 this will apply to all jobs in the group. Below is the list of available
3786 steady state assessment criteria. All assessments are carried out using only
3787 data from the rolling collection window. Threshold limits can be expressed
3788 as a fixed value or as a percentage of the mean in the collection window.
3790 When using this feature, most jobs should include the :option:`time_based`
3791 and :option:`runtime` options or the :option:`loops` option so that fio does not
3792 stop running after it has covered the full size of the specified file(s) or device(s).
3795 Collect IOPS data. Stop the job if all individual IOPS measurements
3796 are within the specified limit of the mean IOPS (e.g., ``iops:2``
3797 means that all individual IOPS values must be within 2 of the mean,
3798 whereas ``iops:0.2%`` means that all individual IOPS values must be
3799 within 0.2% of the mean IOPS to terminate the job).
3802 Collect IOPS data and calculate the least squares regression
3803 slope. Stop the job if the slope falls below the specified limit.
3806 Collect bandwidth data. Stop the job if all individual bandwidth
3807 measurements are within the specified limit of the mean bandwidth.
3810 Collect bandwidth data and calculate the least squares regression
3811 slope. Stop the job if the slope falls below the specified limit.
3813 .. option:: steadystate_duration=time, ss_dur=time
3815 A rolling window of this duration will be used to judge whether steady state
3816 has been reached. Data will be collected once per second. The default is 0
3817 which disables steady state detection. When the unit is omitted, the
3818 value is interpreted in seconds.
3820 .. option:: steadystate_ramp_time=time, ss_ramp=time
3822 Allow the job to run for the specified duration before beginning data
3823 collection for checking the steady state job termination criterion. The
3824 default is 0. When the unit is omitted, the value is interpreted in seconds.
3827 Measurements and reporting
3828 ~~~~~~~~~~~~~~~~~~~~~~~~~~
3830 .. option:: per_job_logs=bool
3832 If set, this generates bw/clat/iops log with per file private filenames. If
3833 not set, jobs with identical names will share the log filename. Default:
3836 .. option:: group_reporting
3838 It may sometimes be interesting to display statistics for groups of jobs as
3839 a whole instead of for each individual job. This is especially true if
3840 :option:`numjobs` is used; looking at individual thread/process output
3841 quickly becomes unwieldy. To see the final report per-group instead of
3842 per-job, use :option:`group_reporting`. Jobs in a file will be part of the
3843 same reporting group, unless if separated by a :option:`stonewall`, or by
3844 using :option:`new_group`.
3846 .. option:: new_group
3848 Start a new reporting group. See: :option:`group_reporting`. If not given,
3849 all jobs in a file will be part of the same reporting group, unless
3850 separated by a :option:`stonewall`.
3852 .. option:: stats=bool
3854 By default, fio collects and shows final output results for all jobs
3855 that run. If this option is set to 0, then fio will ignore it in
3856 the final stat output.
3858 .. option:: write_bw_log=str
3860 If given, write a bandwidth log for this job. Can be used to store data of
3861 the bandwidth of the jobs in their lifetime.
3863 If no str argument is given, the default filename of
3864 :file:`jobname_type.x.log` is used. Even when the argument is given, fio
3865 will still append the type of log. So if one specifies::
3869 The actual log name will be :file:`foo_bw.x.log` where `x` is the index
3870 of the job (`1..N`, where `N` is the number of jobs). If
3871 :option:`per_job_logs` is false, then the filename will not include the
3874 The included :command:`fio_generate_plots` script uses :command:`gnuplot` to turn these
3875 text files into nice graphs. See `Log File Formats`_ for how data is
3876 structured within the file.
3878 .. option:: write_lat_log=str
3880 Same as :option:`write_bw_log`, except this option creates I/O
3881 submission (e.g., :file:`name_slat.x.log`), completion (e.g.,
3882 :file:`name_clat.x.log`), and total (e.g., :file:`name_lat.x.log`)
3883 latency files instead. See :option:`write_bw_log` for details about
3884 the filename format and `Log File Formats`_ for how data is structured
3887 .. option:: write_hist_log=str
3889 Same as :option:`write_bw_log` but writes an I/O completion latency
3890 histogram file (e.g., :file:`name_hist.x.log`) instead. Note that this
3891 file will be empty unless :option:`log_hist_msec` has also been set.
3892 See :option:`write_bw_log` for details about the filename format and
3893 `Log File Formats`_ for how data is structured within the file.
3895 .. option:: write_iops_log=str
3897 Same as :option:`write_bw_log`, but writes an IOPS file (e.g.
3898 :file:`name_iops.x.log`) instead. Because fio defaults to individual
3899 I/O logging, the value entry in the IOPS log will be 1 unless windowed
3900 logging (see :option:`log_avg_msec`) has been enabled. See
3901 :option:`write_bw_log` for details about the filename format and `Log
3902 File Formats`_ for how data is structured within the file.
3904 .. option:: log_entries=int
3906 By default, fio will log an entry in the iops, latency, or bw log for
3907 every I/O that completes. The initial number of I/O log entries is 1024.
3908 When the log entries are all used, new log entries are dynamically
3909 allocated. This dynamic log entry allocation may negatively impact
3910 time-related statistics such as I/O tail latencies (e.g. 99.9th percentile
3911 completion latency). This option allows specifying a larger initial
3912 number of log entries to avoid run-time allocations of new log entries,
3913 resulting in more precise time-related I/O statistics.
3914 Also see :option:`log_avg_msec`. Defaults to 1024.
3916 .. option:: log_avg_msec=int
3918 By default, fio will log an entry in the iops, latency, or bw log for every
3919 I/O that completes. When writing to the disk log, that can quickly grow to a
3920 very large size. Setting this option makes fio average the each log entry
3921 over the specified period of time, reducing the resolution of the log. See
3922 :option:`log_max_value` as well. Defaults to 0, logging all entries.
3923 Also see `Log File Formats`_.
3925 .. option:: log_hist_msec=int
3927 Same as :option:`log_avg_msec`, but logs entries for completion latency
3928 histograms. Computing latency percentiles from averages of intervals using
3929 :option:`log_avg_msec` is inaccurate. Setting this option makes fio log
3930 histogram entries over the specified period of time, reducing log sizes for
3931 high IOPS devices while retaining percentile accuracy. See
3932 :option:`log_hist_coarseness` and :option:`write_hist_log` as well.
3933 Defaults to 0, meaning histogram logging is disabled.
3935 .. option:: log_hist_coarseness=int
3937 Integer ranging from 0 to 6, defining the coarseness of the resolution of
3938 the histogram logs enabled with :option:`log_hist_msec`. For each increment
3939 in coarseness, fio outputs half as many bins. Defaults to 0, for which
3940 histogram logs contain 1216 latency bins. See :option:`write_hist_log`
3941 and `Log File Formats`_.
3943 .. option:: log_max_value=bool
3945 If :option:`log_avg_msec` is set, fio logs the average over that window. If
3946 you instead want to log the maximum value, set this option to 1. Defaults to
3947 0, meaning that averaged values are logged.
3949 .. option:: log_offset=bool
3951 If this is set, the iolog options will include the byte offset for the I/O
3952 entry as well as the other data values. Defaults to 0 meaning that
3953 offsets are not present in logs. Also see `Log File Formats`_.
3955 .. option:: log_compression=int
3957 If this is set, fio will compress the I/O logs as it goes, to keep the
3958 memory footprint lower. When a log reaches the specified size, that chunk is
3959 removed and compressed in the background. Given that I/O logs are fairly
3960 highly compressible, this yields a nice memory savings for longer runs. The
3961 downside is that the compression will consume some background CPU cycles, so
3962 it may impact the run. This, however, is also true if the logging ends up
3963 consuming most of the system memory. So pick your poison. The I/O logs are
3964 saved normally at the end of a run, by decompressing the chunks and storing
3965 them in the specified log file. This feature depends on the availability of
3968 .. option:: log_compression_cpus=str
3970 Define the set of CPUs that are allowed to handle online log compression for
3971 the I/O jobs. This can provide better isolation between performance
3972 sensitive jobs, and background compression work. See
3973 :option:`cpus_allowed` for the format used.
3975 .. option:: log_store_compressed=bool
3977 If set, fio will store the log files in a compressed format. They can be
3978 decompressed with fio, using the :option:`--inflate-log` command line
3979 parameter. The files will be stored with a :file:`.fz` suffix.
3981 .. option:: log_unix_epoch=bool
3983 If set, fio will log Unix timestamps to the log files produced by enabling
3984 write_type_log for each log type, instead of the default zero-based
3987 .. option:: log_alternate_epoch=bool
3989 If set, fio will log timestamps based on the epoch used by the clock specified
3990 in the log_alternate_epoch_clock_id option, to the log files produced by
3991 enabling write_type_log for each log type, instead of the default zero-based
3994 .. option:: log_alternate_epoch_clock_id=int
3996 Specifies the clock_id to be used by clock_gettime to obtain the alternate epoch
3997 if either log_unix_epoch or log_alternate_epoch are true. Otherwise has no
3998 effect. Default value is 0, or CLOCK_REALTIME.
4000 .. option:: block_error_percentiles=bool
4002 If set, record errors in trim block-sized units from writes and trims and
4003 output a histogram of how many trims it took to get to errors, and what kind
4004 of error was encountered.
4006 .. option:: bwavgtime=int
4008 Average the calculated bandwidth over the given time. Value is specified in
4009 milliseconds. If the job also does bandwidth logging through
4010 :option:`write_bw_log`, then the minimum of this option and
4011 :option:`log_avg_msec` will be used. Default: 500ms.
4013 .. option:: iopsavgtime=int
4015 Average the calculated IOPS over the given time. Value is specified in
4016 milliseconds. If the job also does IOPS logging through
4017 :option:`write_iops_log`, then the minimum of this option and
4018 :option:`log_avg_msec` will be used. Default: 500ms.
4020 .. option:: disk_util=bool
4022 Generate disk utilization statistics, if the platform supports it.
4025 .. option:: disable_lat=bool
4027 Disable measurements of total latency numbers. Useful only for cutting back
4028 the number of calls to :manpage:`gettimeofday(2)`, as that does impact
4029 performance at really high IOPS rates. Note that to really get rid of a
4030 large amount of these calls, this option must be used with
4031 :option:`disable_slat` and :option:`disable_bw_measurement` as well.
4033 .. option:: disable_clat=bool
4035 Disable measurements of completion latency numbers. See
4036 :option:`disable_lat`.
4038 .. option:: disable_slat=bool
4040 Disable measurements of submission latency numbers. See
4041 :option:`disable_lat`.
4043 .. option:: disable_bw_measurement=bool, disable_bw=bool
4045 Disable measurements of throughput/bandwidth numbers. See
4046 :option:`disable_lat`.
4048 .. option:: slat_percentiles=bool
4050 Report submission latency percentiles. Submission latency is not recorded
4051 for synchronous ioengines.
4053 .. option:: clat_percentiles=bool
4055 Report completion latency percentiles.
4057 .. option:: lat_percentiles=bool
4059 Report total latency percentiles. Total latency is the sum of submission
4060 latency and completion latency.
4062 .. option:: percentile_list=float_list
4064 Overwrite the default list of percentiles for latencies and the block error
4065 histogram. Each number is a floating point number in the range (0,100], and
4066 the maximum length of the list is 20. Use ``:`` to separate the numbers. For
4067 example, ``--percentile_list=99.5:99.9`` will cause fio to report the
4068 latency durations below which 99.5% and 99.9% of the observed latencies fell,
4071 .. option:: significant_figures=int
4073 If using :option:`--output-format` of `normal`, set the significant
4074 figures to this value. Higher values will yield more precise IOPS and
4075 throughput units, while lower values will round. Requires a minimum
4076 value of 1 and a maximum value of 10. Defaults to 4.
4082 .. option:: exitall_on_error
4084 When one job finishes in error, terminate the rest. The default is to wait
4085 for each job to finish.
4087 .. option:: continue_on_error=str
4089 Normally fio will exit the job on the first observed failure. If this option
4090 is set, fio will continue the job when there is a 'non-fatal error' (EIO or
4091 EILSEQ) until the runtime is exceeded or the I/O size specified is
4092 completed. If this option is used, there are two more stats that are
4093 appended, the total error count and the first error. The error field given
4094 in the stats is the first error that was hit during the run.
4096 Note: a write error from the device may go unnoticed by fio when using
4097 buffered IO, as the write() (or similar) system call merely dirties the
4098 kernel pages, unless :option:`sync` or :option:`direct` is used. Device IO
4099 errors occur when the dirty data is actually written out to disk. If fully
4100 sync writes aren't desirable, :option:`fsync` or :option:`fdatasync` can be
4101 used as well. This is specific to writes, as reads are always synchronous.
4103 The allowed values are:
4106 Exit on any I/O or verify errors.
4109 Continue on read errors, exit on all others.
4112 Continue on write errors, exit on all others.
4115 Continue on any I/O error, exit on all others.
4118 Continue on verify errors, exit on all others.
4121 Continue on all errors.
4124 Backward-compatible alias for 'none'.
4127 Backward-compatible alias for 'all'.
4129 .. option:: ignore_error=str
4131 Sometimes you want to ignore some errors during test in that case you can
4132 specify error list for each error type, instead of only being able to
4133 ignore the default 'non-fatal error' using :option:`continue_on_error`.
4134 ``ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST`` errors for
4135 given error type is separated with ':'. Error may be symbol ('ENOSPC',
4136 'ENOMEM') or integer. Example::
4138 ignore_error=EAGAIN,ENOSPC:122
4140 This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from
4141 WRITE. This option works by overriding :option:`continue_on_error` with
4142 the list of errors for each error type if any.
4144 .. option:: error_dump=bool
4146 If set dump every error even if it is non fatal, true by default. If
4147 disabled only fatal error will be dumped.
4149 Running predefined workloads
4150 ----------------------------
4152 Fio includes predefined profiles that mimic the I/O workloads generated by
4155 .. option:: profile=str
4157 The predefined workload to run. Current profiles are:
4160 Threaded I/O bench (tiotest/tiobench) like workload.
4163 Aerospike Certification Tool (ACT) like workload.
4165 To view a profile's additional options use :option:`--cmdhelp` after specifying
4166 the profile. For example::
4168 $ fio --profile=act --cmdhelp
4173 .. option:: device-names=str
4178 .. option:: load=int
4181 ACT load multiplier. Default: 1.
4183 .. option:: test-duration=time
4186 How long the entire test takes to run. When the unit is omitted, the value
4187 is given in seconds. Default: 24h.
4189 .. option:: threads-per-queue=int
4192 Number of read I/O threads per device. Default: 8.
4194 .. option:: read-req-num-512-blocks=int
4197 Number of 512B blocks to read at the time. Default: 3.
4199 .. option:: large-block-op-kbytes=int
4202 Size of large block ops in KiB (writes). Default: 131072.
4207 Set to run ACT prep phase.
4209 Tiobench profile options
4210 ~~~~~~~~~~~~~~~~~~~~~~~~
4212 .. option:: size=str
4217 .. option:: block=int
4220 Block size in bytes. Default: 4096.
4222 .. option:: numruns=int
4232 .. option:: threads=int
4237 Interpreting the output
4238 -----------------------
4241 Example output was based on the following:
4242 TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --time_based \
4243 --rate=1256k --bs=14K --name=quick --runtime=1s --name=mixed \
4244 --runtime=2m --rw=rw
4246 Fio spits out a lot of output. While running, fio will display the status of the
4247 jobs created. An example of that would be::
4249 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]
4251 The characters inside the first set of square brackets denote the current status of
4252 each thread. The first character is the first job defined in the job file, and so
4253 forth. The possible values (in typical life cycle order) are:
4255 +------+-----+-----------------------------------------------------------+
4257 +======+=====+===========================================================+
4258 | P | | Thread setup, but not started. |
4259 +------+-----+-----------------------------------------------------------+
4260 | C | | Thread created. |
4261 +------+-----+-----------------------------------------------------------+
4262 | I | | Thread initialized, waiting or generating necessary data. |
4263 +------+-----+-----------------------------------------------------------+
4264 | | p | Thread running pre-reading file(s). |
4265 +------+-----+-----------------------------------------------------------+
4266 | | / | Thread is in ramp period. |
4267 +------+-----+-----------------------------------------------------------+
4268 | | R | Running, doing sequential reads. |
4269 +------+-----+-----------------------------------------------------------+
4270 | | r | Running, doing random reads. |
4271 +------+-----+-----------------------------------------------------------+
4272 | | W | Running, doing sequential writes. |
4273 +------+-----+-----------------------------------------------------------+
4274 | | w | Running, doing random writes. |
4275 +------+-----+-----------------------------------------------------------+
4276 | | M | Running, doing mixed sequential reads/writes. |
4277 +------+-----+-----------------------------------------------------------+
4278 | | m | Running, doing mixed random reads/writes. |
4279 +------+-----+-----------------------------------------------------------+
4280 | | D | Running, doing sequential trims. |
4281 +------+-----+-----------------------------------------------------------+
4282 | | d | Running, doing random trims. |
4283 +------+-----+-----------------------------------------------------------+
4284 | | F | Running, currently waiting for :manpage:`fsync(2)`. |
4285 +------+-----+-----------------------------------------------------------+
4286 | | V | Running, doing verification of written data. |
4287 +------+-----+-----------------------------------------------------------+
4288 | f | | Thread finishing. |
4289 +------+-----+-----------------------------------------------------------+
4290 | E | | Thread exited, not reaped by main thread yet. |
4291 +------+-----+-----------------------------------------------------------+
4292 | _ | | Thread reaped. |
4293 +------+-----+-----------------------------------------------------------+
4294 | X | | Thread reaped, exited with an error. |
4295 +------+-----+-----------------------------------------------------------+
4296 | K | | Thread reaped, exited due to signal. |
4297 +------+-----+-----------------------------------------------------------+
4300 Example output was based on the following:
4301 TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --runtime=58m \
4302 --time_based --rate=2512k --bs=256K --numjobs=10 \
4303 --name=readers --rw=read --name=writers --rw=write
4305 Fio will condense the thread string as not to take up more space on the command
4306 line than needed. For instance, if you have 10 readers and 10 writers running,
4307 the output would look like this::
4309 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]
4311 Note that the status string is displayed in order, so it's possible to tell which of
4312 the jobs are currently doing what. In the example above this means that jobs 1--10
4313 are readers and 11--20 are writers.
4315 The other values are fairly self explanatory -- number of threads currently
4316 running and doing I/O, the number of currently open files (f=), the estimated
4317 completion percentage, the rate of I/O since last check (read speed listed first,
4318 then write speed and optionally trim speed) in terms of bandwidth and IOPS,
4319 and time to completion for the current running group. It's impossible to estimate
4320 runtime of the following groups (if any).
4323 Example output was based on the following:
4324 TZ=UTC fio --iodepth=16 --ioengine=posixaio --filename=/tmp/fiofile \
4325 --direct=1 --size=100M --time_based --runtime=50s --rate_iops=89 \
4326 --bs=7K --name=Client1 --rw=write
4328 When fio is done (or interrupted by :kbd:`Ctrl-C`), it will show the data for
4329 each thread, group of threads, and disks in that order. For each overall thread (or
4330 group) the output looks like::
4332 Client1: (groupid=0, jobs=1): err= 0: pid=16109: Sat Jun 24 12:07:54 2017
4333 write: IOPS=88, BW=623KiB/s (638kB/s)(30.4MiB/50032msec)
4334 slat (nsec): min=500, max=145500, avg=8318.00, stdev=4781.50
4335 clat (usec): min=170, max=78367, avg=4019.02, stdev=8293.31
4336 lat (usec): min=174, max=78375, avg=4027.34, stdev=8291.79
4337 clat percentiles (usec):
4338 | 1.00th=[ 302], 5.00th=[ 326], 10.00th=[ 343], 20.00th=[ 363],
4339 | 30.00th=[ 392], 40.00th=[ 404], 50.00th=[ 416], 60.00th=[ 445],
4340 | 70.00th=[ 816], 80.00th=[ 6718], 90.00th=[12911], 95.00th=[21627],
4341 | 99.00th=[43779], 99.50th=[51643], 99.90th=[68682], 99.95th=[72877],
4343 bw ( KiB/s): min= 532, max= 686, per=0.10%, avg=622.87, stdev=24.82, samples= 100
4344 iops : min= 76, max= 98, avg=88.98, stdev= 3.54, samples= 100
4345 lat (usec) : 250=0.04%, 500=64.11%, 750=4.81%, 1000=2.79%
4346 lat (msec) : 2=4.16%, 4=1.84%, 10=4.90%, 20=11.33%, 50=5.37%
4347 lat (msec) : 100=0.65%
4348 cpu : usr=0.27%, sys=0.18%, ctx=12072, majf=0, minf=21
4349 IO depths : 1=85.0%, 2=13.1%, 4=1.8%, 8=0.1%, 16=0.0%, 32=0.0%, >=64=0.0%
4350 submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
4351 complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
4352 issued rwt: total=0,4450,0, short=0,0,0, dropped=0,0,0
4353 latency : target=0, window=0, percentile=100.00%, depth=8
4355 The job name (or first job's name when using :option:`group_reporting`) is printed,
4356 along with the group id, count of jobs being aggregated, last error id seen (which
4357 is 0 when there are no errors), pid/tid of that thread and the time the job/group
4358 completed. Below are the I/O statistics for each data direction performed (showing
4359 writes in the example above). In the order listed, they denote:
4362 The string before the colon shows the I/O direction the statistics
4363 are for. **IOPS** is the average I/Os performed per second. **BW**
4364 is the average bandwidth rate shown as: value in power of 2 format
4365 (value in power of 10 format). The last two values show: (**total
4366 I/O performed** in power of 2 format / **runtime** of that thread).
4369 Submission latency (**min** being the minimum, **max** being the
4370 maximum, **avg** being the average, **stdev** being the standard
4371 deviation). This is the time from when fio initialized the I/O
4372 to submission. For synchronous ioengines this includes the time
4373 up until just before the ioengine's queue function is called.
4374 For asynchronous ioengines this includes the time up through the
4375 completion of the ioengine's queue function (and commit function
4376 if it is defined). For sync I/O this row is not displayed as the
4377 slat is negligible. This value can be in nanoseconds,
4378 microseconds or milliseconds --- fio will choose the most
4379 appropriate base and print that (in the example above
4380 nanoseconds was the best scale). Note: in :option:`--minimal`
4381 mode latencies are always expressed in microseconds.
4384 Completion latency. Same names as slat, this denotes the time from
4385 submission to completion of the I/O pieces. For sync I/O, this
4386 represents the time from when the I/O was submitted to the
4387 operating system to when it was completed. For asynchronous
4388 ioengines this is the time from when the ioengine's queue (and
4389 commit if available) functions were completed to when the I/O's
4390 completion was reaped by fio.
4393 Total latency. Same names as slat and clat, this denotes the time from
4394 when fio created the I/O unit to completion of the I/O operation.
4395 It is the sum of submission and completion latency.
4398 Bandwidth statistics based on samples. Same names as the xlat stats,
4399 but also includes the number of samples taken (**samples**) and an
4400 approximate percentage of total aggregate bandwidth this thread
4401 received in its group (**per**). This last value is only really
4402 useful if the threads in this group are on the same disk, since they
4403 are then competing for disk access.
4406 IOPS statistics based on samples. Same names as bw.
4408 **lat (nsec/usec/msec)**
4409 The distribution of I/O completion latencies. This is the time from when
4410 I/O leaves fio and when it gets completed. Unlike the separate
4411 read/write/trim sections above, the data here and in the remaining
4412 sections apply to all I/Os for the reporting group. 250=0.04% means that
4413 0.04% of the I/Os completed in under 250us. 500=64.11% means that 64.11%
4414 of the I/Os required 250 to 499us for completion.
4417 CPU usage. User and system time, along with the number of context
4418 switches this thread went through, usage of system and user time, and
4419 finally the number of major and minor page faults. The CPU utilization
4420 numbers are averages for the jobs in that reporting group, while the
4421 context and fault counters are summed.
4424 The distribution of I/O depths over the job lifetime. The numbers are
4425 divided into powers of 2 and each entry covers depths from that value
4426 up to those that are lower than the next entry -- e.g., 16= covers
4427 depths from 16 to 31. Note that the range covered by a depth
4428 distribution entry can be different to the range covered by the
4429 equivalent submit/complete distribution entry.
4432 How many pieces of I/O were submitting in a single submit call. Each
4433 entry denotes that amount and below, until the previous entry -- e.g.,
4434 16=100% means that we submitted anywhere between 9 to 16 I/Os per submit
4435 call. Note that the range covered by a submit distribution entry can
4436 be different to the range covered by the equivalent depth distribution
4440 Like the above submit number, but for completions instead.
4443 The number of read/write/trim requests issued, and how many of them were
4447 These values are for :option:`latency_target` and related options. When
4448 these options are engaged, this section describes the I/O depth required
4449 to meet the specified latency target.
4452 Example output was based on the following:
4453 TZ=UTC fio --ioengine=null --iodepth=2 --size=100M --numjobs=2 \
4454 --rate_process=poisson --io_limit=32M --name=read --bs=128k \
4455 --rate=11M --name=write --rw=write --bs=2k --rate=700k
4457 After each client has been listed, the group statistics are printed. They
4458 will look like this::
4460 Run status group 0 (all jobs):
4461 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
4462 WRITE: bw=1231KiB/s (1261kB/s), 616KiB/s-621KiB/s (630kB/s-636kB/s), io=64.0MiB (67.1MB), run=52747-53223msec
4464 For each data direction it prints:
4467 Aggregate bandwidth of threads in this group followed by the
4468 minimum and maximum bandwidth of all the threads in this group.
4469 Values outside of brackets are power-of-2 format and those
4470 within are the equivalent value in a power-of-10 format.
4472 Aggregate I/O performed of all threads in this group. The
4473 format is the same as bw.
4475 The smallest and longest runtimes of the threads in this group.
4477 And finally, the disk statistics are printed. This is Linux specific. They will look like this::
4479 Disk stats (read/write):
4480 sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00%
4482 Each value is printed for both reads and writes, with reads first. The
4486 Number of I/Os performed by all groups.
4488 Number of merges performed by the I/O scheduler.
4490 Number of ticks we kept the disk busy.
4492 Total time spent in the disk queue.
4494 The disk utilization. A value of 100% means we kept the disk
4495 busy constantly, 50% would be a disk idling half of the time.
4497 It is also possible to get fio to dump the current output while it is running,
4498 without terminating the job. To do that, send fio the **USR1** signal. You can
4499 also get regularly timed dumps by using the :option:`--status-interval`
4500 parameter, or by creating a file in :file:`/tmp` named
4501 :file:`fio-dump-status`. If fio sees this file, it will unlink it and dump the
4502 current output status.
4508 For scripted usage where you typically want to generate tables or graphs of the
4509 results, fio can output the results in a semicolon separated format. The format
4510 is one long line of values, such as::
4512 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%
4513 A description of this job goes here.
4515 The job description (if provided) follows on a second line for terse v2.
4516 It appears on the same line for other terse versions.
4518 To enable terse output, use the :option:`--minimal` or
4519 :option:`--output-format`\=terse command line options. The
4520 first value is the version of the terse output format. If the output has to be
4521 changed for some reason, this number will be incremented by 1 to signify that
4524 Split up, the format is as follows (comments in brackets denote when a
4525 field was introduced or whether it's specific to some terse version):
4529 terse version, fio version [v3], jobname, groupid, error
4533 Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
4534 Submission latency: min, max, mean, stdev (usec)
4535 Completion latency: min, max, mean, stdev (usec)
4536 Completion latency percentiles: 20 fields (see below)
4537 Total latency: min, max, mean, stdev (usec)
4538 Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
4539 IOPS [v5]: min, max, mean, stdev, number of samples
4545 Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
4546 Submission latency: min, max, mean, stdev (usec)
4547 Completion latency: min, max, mean, stdev (usec)
4548 Completion latency percentiles: 20 fields (see below)
4549 Total latency: min, max, mean, stdev (usec)
4550 Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
4551 IOPS [v5]: min, max, mean, stdev, number of samples
4553 TRIM status [all but version 3]:
4555 Fields are similar to READ/WRITE status.
4559 user, system, context switches, major faults, minor faults
4563 <=1, 2, 4, 8, 16, 32, >=64
4565 I/O latencies microseconds::
4567 <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
4569 I/O latencies milliseconds::
4571 <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
4573 Disk utilization [v3]::
4575 disk name, read ios, write ios, read merges, write merges, read ticks, write ticks,
4576 time spent in queue, disk utilization percentage
4578 Additional Info (dependent on continue_on_error, default off)::
4580 total # errors, first error code
4582 Additional Info (dependent on description being set)::
4586 Completion latency percentiles can be a grouping of up to 20 sets, so for the
4587 terse output fio writes all of them. Each field will look like this::
4591 which is the Xth percentile, and the `usec` latency associated with it.
4593 For `Disk utilization`, all disks used by fio are shown. So for each disk there
4594 will be a disk utilization section.
4596 Below is a single line containing short names for each of the fields in the
4597 minimal output v3, separated by semicolons::
4599 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
4601 In client/server mode terse output differs from what appears when jobs are run
4602 locally. Disk utilization data is omitted from the standard terse output and
4603 for v3 and later appears on its own separate line at the end of each terse
4610 The `json` output format is intended to be both human readable and convenient
4611 for automated parsing. For the most part its sections mirror those of the
4612 `normal` output. The `runtime` value is reported in msec and the `bw` value is
4613 reported in 1024 bytes per second units.
4619 The `json+` output format is identical to the `json` output format except that it
4620 adds a full dump of the completion latency bins. Each `bins` object contains a
4621 set of (key, value) pairs where keys are latency durations and values count how
4622 many I/Os had completion latencies of the corresponding duration. For example,
4625 "bins" : { "87552" : 1, "89600" : 1, "94720" : 1, "96768" : 1, "97792" : 1, "99840" : 1, "100864" : 2, "103936" : 6, "104960" : 534, "105984" : 5995, "107008" : 7529, ... }
4627 This data indicates that one I/O required 87,552ns to complete, two I/Os required
4628 100,864ns to complete, and 7529 I/Os required 107,008ns to complete.
4630 Also included with fio is a Python script `fio_jsonplus_clat2csv` that takes
4631 json+ output and generates CSV-formatted latency data suitable for plotting.
4633 The latency durations actually represent the midpoints of latency intervals.
4634 For details refer to :file:`stat.h`.
4640 There are two trace file format that you can encounter. The older (v1) format is
4641 unsupported since version 1.20-rc3 (March 2008). It will still be described
4642 below in case that you get an old trace and want to understand it.
4644 In any case the trace is a simple text file with a single action per line.
4647 Trace file format v1
4648 ~~~~~~~~~~~~~~~~~~~~
4650 Each line represents a single I/O action in the following format::
4654 where `rw=0/1` for read/write, and the `offset` and `length` entries being in bytes.
4656 This format is not supported in fio versions >= 1.20-rc3.
4659 Trace file format v2
4660 ~~~~~~~~~~~~~~~~~~~~
4662 The second version of the trace file format was added in fio version 1.17. It
4663 allows one to access more than one file per trace and has a bigger set of possible
4666 The first line of the trace file has to be::
4670 Following this can be lines in two different formats, which are described below.
4672 The file management format::
4676 The `filename` is given as an absolute path. The `action` can be one of these:
4679 Add the given `filename` to the trace.
4681 Open the file with the given `filename`. The `filename` has to have
4682 been added with the **add** action before.
4684 Close the file with the given `filename`. The file has to have been
4688 The file I/O action format::
4690 filename action offset length
4692 The `filename` is given as an absolute path, and has to have been added and
4693 opened before it can be used with this format. The `offset` and `length` are
4694 given in bytes. The `action` can be one of these:
4697 Wait for `offset` microseconds. Everything below 100 is discarded.
4698 The time is relative to the previous `wait` statement. Note that
4699 action `wait` is not allowed as of version 3, as the same behavior
4700 can be achieved using timestamps.
4702 Read `length` bytes beginning from `offset`.
4704 Write `length` bytes beginning from `offset`.
4706 :manpage:`fsync(2)` the file.
4708 :manpage:`fdatasync(2)` the file.
4710 Trim the given file from the given `offset` for `length` bytes.
4713 Trace file format v3
4714 ~~~~~~~~~~~~~~~~~~~~
4716 The third version of the trace file format was added in fio version 3.31. It
4717 forces each action to have a timestamp associated with it.
4719 The first line of the trace file has to be::
4723 Following this can be lines in two different formats, which are described below.
4725 The file management format::
4727 timestamp filename action
4729 The file I/O action format::
4731 timestamp filename action offset length
4733 The `timestamp` is relative to the beginning of the run (ie starts at 0). The
4734 `filename`, `action`, `offset` and `length` are identical to version 2, except
4735 that version 3 does not allow the `wait` action.
4738 I/O Replay - Merging Traces
4739 ---------------------------
4741 Colocation is a common practice used to get the most out of a machine.
4742 Knowing which workloads play nicely with each other and which ones don't is
4743 a much harder task. While fio can replay workloads concurrently via multiple
4744 jobs, it leaves some variability up to the scheduler making results harder to
4745 reproduce. Merging is a way to make the order of events consistent.
4747 Merging is integrated into I/O replay and done when a
4748 :option:`merge_blktrace_file` is specified. The list of files passed to
4749 :option:`read_iolog` go through the merge process and output a single file
4750 stored to the specified file. The output file is passed on as if it were the
4751 only file passed to :option:`read_iolog`. An example would look like::
4753 $ fio --read_iolog="<file1>:<file2>" --merge_blktrace_file="<output_file>"
4755 Creating only the merged file can be done by passing the command line argument
4756 :option:`--merge-blktrace-only`.
4758 Scaling traces can be done to see the relative impact of any particular trace
4759 being slowed down or sped up. :option:`merge_blktrace_scalars` takes in a colon
4760 separated list of percentage scalars. It is index paired with the files passed
4761 to :option:`read_iolog`.
4763 With scaling, it may be desirable to match the running time of all traces.
4764 This can be done with :option:`merge_blktrace_iters`. It is index paired with
4765 :option:`read_iolog` just like :option:`merge_blktrace_scalars`.
4767 In an example, given two traces, A and B, each 60s long. If we want to see
4768 the impact of trace A issuing IOs twice as fast and repeat trace A over the
4769 runtime of trace B, the following can be done::
4771 $ fio --read_iolog="<trace_a>:"<trace_b>" --merge_blktrace_file"<output_file>" --merge_blktrace_scalars="50:100" --merge_blktrace_iters="2:1"
4773 This runs trace A at 2x the speed twice for approximately the same runtime as
4774 a single run of trace B.
4777 CPU idleness profiling
4778 ----------------------
4780 In some cases, we want to understand CPU overhead in a test. For example, we
4781 test patches for the specific goodness of whether they reduce CPU usage.
4782 Fio implements a balloon approach to create a thread per CPU that runs at idle
4783 priority, meaning that it only runs when nobody else needs the cpu.
4784 By measuring the amount of work completed by the thread, idleness of each CPU
4785 can be derived accordingly.
4787 An unit work is defined as touching a full page of unsigned characters. Mean and
4788 standard deviation of time to complete an unit work is reported in "unit work"
4789 section. Options can be chosen to report detailed percpu idleness or overall
4790 system idleness by aggregating percpu stats.
4793 Verification and triggers
4794 -------------------------
4796 Fio is usually run in one of two ways, when data verification is done. The first
4797 is a normal write job of some sort with verify enabled. When the write phase has
4798 completed, fio switches to reads and verifies everything it wrote. The second
4799 model is running just the write phase, and then later on running the same job
4800 (but with reads instead of writes) to repeat the same I/O patterns and verify
4801 the contents. Both of these methods depend on the write phase being completed,
4802 as fio otherwise has no idea how much data was written.
4804 With verification triggers, fio supports dumping the current write state to
4805 local files. Then a subsequent read verify workload can load this state and know
4806 exactly where to stop. This is useful for testing cases where power is cut to a
4807 server in a managed fashion, for instance.
4809 A verification trigger consists of two things:
4811 1) Storing the write state of each job.
4812 2) Executing a trigger command.
4814 The write state is relatively small, on the order of hundreds of bytes to single
4815 kilobytes. It contains information on the number of completions done, the last X
4818 A trigger is invoked either through creation ('touch') of a specified file in
4819 the system, or through a timeout setting. If fio is run with
4820 :option:`--trigger-file`\= :file:`/tmp/trigger-file`, then it will continually
4821 check for the existence of :file:`/tmp/trigger-file`. When it sees this file, it
4822 will fire off the trigger (thus saving state, and executing the trigger
4825 For client/server runs, there's both a local and remote trigger. If fio is
4826 running as a server backend, it will send the job states back to the client for
4827 safe storage, then execute the remote trigger, if specified. If a local trigger
4828 is specified, the server will still send back the write state, but the client
4829 will then execute the trigger.
4831 Verification trigger example
4832 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
4834 Let's say we want to run a powercut test on the remote Linux machine 'server'.
4835 Our write workload is in :file:`write-test.fio`. We want to cut power to 'server' at
4836 some point during the run, and we'll run this test from the safety or our local
4837 machine, 'localbox'. On the server, we'll start the fio backend normally::
4839 server# fio --server
4841 and on the client, we'll fire off the workload::
4843 localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger-remote="bash -c \"echo b > /proc/sysrq-triger\""
4845 We set :file:`/tmp/my-trigger` as the trigger file, and we tell fio to execute::
4847 echo b > /proc/sysrq-trigger
4849 on the server once it has received the trigger and sent us the write state. This
4850 will work, but it's not **really** cutting power to the server, it's merely
4851 abruptly rebooting it. If we have a remote way of cutting power to the server
4852 through IPMI or similar, we could do that through a local trigger command
4853 instead. Let's assume we have a script that does IPMI reboot of a given hostname,
4854 ipmi-reboot. On localbox, we could then have run fio with a local trigger
4857 localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger="ipmi-reboot server"
4859 For this case, fio would wait for the server to send us the write state, then
4860 execute ``ipmi-reboot server`` when that happened.
4862 Loading verify state
4863 ~~~~~~~~~~~~~~~~~~~~
4865 To load stored write state, a read verification job file must contain the
4866 :option:`verify_state_load` option. If that is set, fio will load the previously
4867 stored state. For a local fio run this is done by loading the files directly,
4868 and on a client/server run, the server backend will ask the client to send the
4869 files over and load them from there.
4875 Fio supports a variety of log file formats, for logging latencies, bandwidth,
4876 and IOPS. The logs share a common format, which looks like this:
4878 *time* (`msec`), *value*, *data direction*, *block size* (`bytes`),
4879 *offset* (`bytes`), *command priority*
4881 *Time* for the log entry is always in milliseconds. The *value* logged depends
4882 on the type of log, it will be one of the following:
4885 Value is latency in nsecs
4891 *Data direction* is one of the following:
4900 The entry's *block size* is always in bytes. The *offset* is the position in bytes
4901 from the start of the file for that particular I/O. The logging of the offset can be
4902 toggled with :option:`log_offset`.
4904 *Command priority* is 0 for normal priority and 1 for high priority. This is controlled
4905 by the ioengine specific :option:`cmdprio_percentage`.
4907 Fio defaults to logging every individual I/O but when windowed logging is set
4908 through :option:`log_avg_msec`, either the average (by default) or the maximum
4909 (:option:`log_max_value` is set) *value* seen over the specified period of time
4910 is recorded. Each *data direction* seen within the window period will aggregate
4911 its values in a separate row. Further, when using windowed logging the *block
4912 size* and *offset* entries will always contain 0.
4918 Normally fio is invoked as a stand-alone application on the machine where the
4919 I/O workload should be generated. However, the backend and frontend of fio can
4920 be run separately i.e., the fio server can generate an I/O workload on the "Device
4921 Under Test" while being controlled by a client on another machine.
4923 Start the server on the machine which has access to the storage DUT::
4927 where `args` defines what fio listens to. The arguments are of the form
4928 ``type,hostname`` or ``IP,port``. *type* is either ``ip`` (or ip4) for TCP/IP
4929 v4, ``ip6`` for TCP/IP v6, or ``sock`` for a local unix domain socket.
4930 *hostname* is either a hostname or IP address, and *port* is the port to listen
4931 to (only valid for TCP/IP, not a local socket). Some examples:
4935 Start a fio server, listening on all interfaces on the default port (8765).
4937 2) ``fio --server=ip:hostname,4444``
4939 Start a fio server, listening on IP belonging to hostname and on port 4444.
4941 3) ``fio --server=ip6:::1,4444``
4943 Start a fio server, listening on IPv6 localhost ::1 and on port 4444.
4945 4) ``fio --server=,4444``
4947 Start a fio server, listening on all interfaces on port 4444.
4949 5) ``fio --server=1.2.3.4``
4951 Start a fio server, listening on IP 1.2.3.4 on the default port.
4953 6) ``fio --server=sock:/tmp/fio.sock``
4955 Start a fio server, listening on the local socket :file:`/tmp/fio.sock`.
4957 Once a server is running, a "client" can connect to the fio server with::
4959 fio <local-args> --client=<server> <remote-args> <job file(s)>
4961 where `local-args` are arguments for the client where it is running, `server`
4962 is the connect string, and `remote-args` and `job file(s)` are sent to the
4963 server. The `server` string follows the same format as it does on the server
4964 side, to allow IP/hostname/socket and port strings.
4966 Fio can connect to multiple servers this way::
4968 fio --client=<server1> <job file(s)> --client=<server2> <job file(s)>
4970 If the job file is located on the fio server, then you can tell the server to
4971 load a local file as well. This is done by using :option:`--remote-config` ::
4973 fio --client=server --remote-config /path/to/file.fio
4975 Then fio will open this local (to the server) job file instead of being passed
4976 one from the client.
4978 If you have many servers (example: 100 VMs/containers), you can input a pathname
4979 of a file containing host IPs/names as the parameter value for the
4980 :option:`--client` option. For example, here is an example :file:`host.list`
4981 file containing 2 hostnames::
4983 host1.your.dns.domain
4984 host2.your.dns.domain
4986 The fio command would then be::
4988 fio --client=host.list <job file(s)>
4990 In this mode, you cannot input server-specific parameters or job files -- all
4991 servers receive the same job file.
4993 In order to let ``fio --client`` runs use a shared filesystem from multiple
4994 hosts, ``fio --client`` now prepends the IP address of the server to the
4995 filename. For example, if fio is using the directory :file:`/mnt/nfs/fio` and is
4996 writing filename :file:`fileio.tmp`, with a :option:`--client` `hostfile`
4997 containing two hostnames ``h1`` and ``h2`` with IP addresses 192.168.10.120 and
4998 192.168.10.121, then fio will create two files::
5000 /mnt/nfs/fio/192.168.10.120.fileio.tmp
5001 /mnt/nfs/fio/192.168.10.121.fileio.tmp
5003 Terse output in client/server mode will differ slightly from what is produced
5004 when fio is run in stand-alone mode. See the terse output section for details.