Documentation: add note about how many bssplit and zones fio supports
[fio.git] / HOWTO
CommitLineData
f80dba8d
MT
1How fio works
2-------------
3
4The first step in getting fio to simulate a desired I/O workload, is writing a
5job file describing that specific setup. A job file may contain any number of
6threads and/or files -- the typical contents of the job file is a *global*
7section defining shared parameters, and one or more job sections describing the
8jobs involved. When run, fio parses this file and sets everything up as
9described. If we break down a job from top to bottom, it contains the following
10basic parameters:
11
12`I/O type`_
13
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?
18
19`Block size`_
20
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.
23
24`I/O size`_
25
26 How much data are we going to be reading/writing.
27
28`I/O engine`_
29
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
32 SG (SCSI generic sg).
33
34`I/O depth`_
35
36 If the I/O engine is async, how large a queuing depth do we want to
37 maintain?
38
39
40`Target file/device`_
41
42 How many files are we spreading the workload over.
43
44`Threads, processes and job synchronization`_
45
46 How many threads or processes should we spread this workload over.
47
48The above are the basic parameters defined for a workload, in addition there's a
49multitude of parameters that modify other aspects of how this job behaves.
50
51
52Command line options
53--------------------
54
55.. option:: --debug=type
56
f50fbdda 57 Enable verbose tracing `type` of various fio actions. May be ``all`` for all types
b034c0dd
TK
58 or individual types separated by a comma (e.g. ``--debug=file,mem`` will
59 enable file and memory debugging). Currently, additional logging is
60 available for:
f80dba8d 61
b034c0dd 62 *process*
f80dba8d 63 Dump info related to processes.
b034c0dd 64 *file*
f80dba8d 65 Dump info related to file actions.
b034c0dd 66 *io*
f80dba8d 67 Dump info related to I/O queuing.
b034c0dd 68 *mem*
f80dba8d 69 Dump info related to memory allocations.
b034c0dd 70 *blktrace*
f80dba8d 71 Dump info related to blktrace setup.
b034c0dd 72 *verify*
f80dba8d 73 Dump info related to I/O verification.
b034c0dd 74 *all*
f80dba8d 75 Enable all debug options.
b034c0dd 76 *random*
f80dba8d 77 Dump info related to random offset generation.
b034c0dd 78 *parse*
f80dba8d 79 Dump info related to option matching and parsing.
b034c0dd 80 *diskutil*
f80dba8d 81 Dump info related to disk utilization updates.
b034c0dd 82 *job:x*
f80dba8d 83 Dump info only related to job number x.
b034c0dd 84 *mutex*
f80dba8d 85 Dump info only related to mutex up/down ops.
b034c0dd 86 *profile*
f80dba8d 87 Dump info related to profile extensions.
b034c0dd 88 *time*
f80dba8d 89 Dump info related to internal time keeping.
b034c0dd 90 *net*
f80dba8d 91 Dump info related to networking connections.
b034c0dd 92 *rate*
f80dba8d 93 Dump info related to I/O rate switching.
b034c0dd 94 *compress*
f80dba8d 95 Dump info related to log compress/decompress.
b034c0dd 96 *?* or *help*
f80dba8d
MT
97 Show available debug options.
98
99.. option:: --parse-only
100
25cd4b95 101 Parse options only, don't start any I/O.
f80dba8d
MT
102
103.. option:: --output=filename
104
105 Write output to file `filename`.
106
f50fbdda 107.. option:: --output-format=format
b8f7e412 108
f50fbdda 109 Set the reporting `format` to `normal`, `terse`, `json`, or `json+`. Multiple
b8f7e412
TK
110 formats can be selected, separated by a comma. `terse` is a CSV based
111 format. `json+` is like `json`, except it adds a full dump of the latency
112 buckets.
113
f80dba8d
MT
114.. option:: --bandwidth-log
115
116 Generate aggregate bandwidth logs.
117
118.. option:: --minimal
119
120 Print statistics in a terse, semicolon-delimited format.
121
122.. option:: --append-terse
123
b034c0dd
TK
124 Print statistics in selected mode AND terse, semicolon-delimited format.
125 **Deprecated**, use :option:`--output-format` instead to select multiple
126 formats.
f80dba8d 127
f50fbdda 128.. option:: --terse-version=version
f80dba8d 129
f50fbdda 130 Set terse `version` output format (default 3, or 2 or 4 or 5).
f80dba8d
MT
131
132.. option:: --version
133
b8f7e412 134 Print version information and exit.
f80dba8d
MT
135
136.. option:: --help
137
113f0e7c 138 Print a summary of the command line options and exit.
f80dba8d
MT
139
140.. option:: --cpuclock-test
141
142 Perform test and validation of internal CPU clock.
143
113f0e7c 144.. option:: --crctest=[test]
f80dba8d 145
b034c0dd
TK
146 Test the speed of the built-in checksumming functions. If no argument is
147 given, all of them are tested. Alternatively, a comma separated list can
148 be passed, in which case the given ones are tested.
f80dba8d
MT
149
150.. option:: --cmdhelp=command
151
152 Print help information for `command`. May be ``all`` for all commands.
153
154.. option:: --enghelp=[ioengine[,command]]
155
f50fbdda
TK
156 List all commands defined by `ioengine`, or print help for `command`
157 defined by `ioengine`. If no `ioengine` is given, list all
b034c0dd 158 available ioengines.
f80dba8d
MT
159
160.. option:: --showcmd=jobfile
161
b8f7e412 162 Convert `jobfile` to a set of command-line options.
f80dba8d
MT
163
164.. option:: --readonly
165
b034c0dd
TK
166 Turn on safety read-only checks, preventing writes. The ``--readonly``
167 option is an extra safety guard to prevent users from accidentally starting
168 a write workload when that is not desired. Fio will only write if
169 `rw=write/randwrite/rw/randrw` is given. This extra safety net can be used
170 as an extra precaution as ``--readonly`` will also enable a write check in
171 the I/O engine core to prevent writes due to unknown user space bug(s).
f80dba8d
MT
172
173.. option:: --eta=when
174
b8f7e412
TK
175 Specifies when real-time ETA estimate should be printed. `when` may be
176 `always`, `never` or `auto`.
f80dba8d
MT
177
178.. option:: --eta-newline=time
179
947e0fe0
SW
180 Force a new line for every `time` period passed. When the unit is omitted,
181 the value is interpreted in seconds.
f80dba8d
MT
182
183.. option:: --status-interval=time
184
aa6cb459
VF
185 Force a full status dump of cumulative (from job start) values at `time`
186 intervals. This option does *not* provide per-period measurements. So
187 values such as bandwidth are running averages. When the time unit is omitted,
188 `time` is interpreted in seconds.
f80dba8d
MT
189
190.. option:: --section=name
191
b034c0dd
TK
192 Only run specified section `name` in job file. Multiple sections can be specified.
193 The ``--section`` option allows one to combine related jobs into one file.
194 E.g. one job file could define light, moderate, and heavy sections. Tell
195 fio to run only the "heavy" section by giving ``--section=heavy``
196 command line option. One can also specify the "write" operations in one
197 section and "verify" operation in another section. The ``--section`` option
198 only applies to job sections. The reserved *global* section is always
199 parsed and used.
f80dba8d
MT
200
201.. option:: --alloc-size=kb
202
b034c0dd
TK
203 Set the internal smalloc pool size to `kb` in KiB. The
204 ``--alloc-size`` switch allows one to use a larger pool size for smalloc.
205 If running large jobs with randommap enabled, fio can run out of memory.
206 Smalloc is an internal allocator for shared structures from a fixed size
207 memory pool and can grow to 16 pools. The pool size defaults to 16MiB.
f80dba8d 208
b034c0dd
TK
209 NOTE: While running :file:`.fio_smalloc.*` backing store files are visible
210 in :file:`/tmp`.
f80dba8d
MT
211
212.. option:: --warnings-fatal
213
b034c0dd
TK
214 All fio parser warnings are fatal, causing fio to exit with an
215 error.
f80dba8d
MT
216
217.. option:: --max-jobs=nr
218
f50fbdda 219 Set the maximum number of threads/processes to support to `nr`.
818322cc 220 NOTE: On Linux, it may be necessary to increase the shared-memory
71aa48eb 221 limit (:file:`/proc/sys/kernel/shmmax`) if fio runs into errors while
818322cc 222 creating jobs.
f80dba8d
MT
223
224.. option:: --server=args
225
b034c0dd
TK
226 Start a backend server, with `args` specifying what to listen to.
227 See `Client/Server`_ section.
f80dba8d
MT
228
229.. option:: --daemonize=pidfile
230
b034c0dd 231 Background a fio server, writing the pid to the given `pidfile` file.
f80dba8d
MT
232
233.. option:: --client=hostname
234
f50fbdda 235 Instead of running the jobs locally, send and run them on the given `hostname`
71aa48eb 236 or set of `hostname`\s. See `Client/Server`_ section.
f80dba8d
MT
237
238.. option:: --remote-config=file
239
f50fbdda 240 Tell fio server to load this local `file`.
f80dba8d
MT
241
242.. option:: --idle-prof=option
243
b8f7e412 244 Report CPU idleness. `option` is one of the following:
113f0e7c
SW
245
246 **calibrate**
247 Run unit work calibration only and exit.
248
249 **system**
250 Show aggregate system idleness and unit work.
251
252 **percpu**
253 As **system** but also show per CPU idleness.
f80dba8d
MT
254
255.. option:: --inflate-log=log
256
f50fbdda 257 Inflate and output compressed `log`.
f80dba8d
MT
258
259.. option:: --trigger-file=file
260
f50fbdda 261 Execute trigger command when `file` exists.
f80dba8d 262
f50fbdda 263.. option:: --trigger-timeout=time
f80dba8d 264
f50fbdda 265 Execute trigger at this `time`.
f80dba8d 266
f50fbdda 267.. option:: --trigger=command
f80dba8d 268
f50fbdda 269 Set this `command` as local trigger.
f80dba8d 270
f50fbdda 271.. option:: --trigger-remote=command
f80dba8d 272
f50fbdda 273 Set this `command` as remote trigger.
f80dba8d
MT
274
275.. option:: --aux-path=path
276
f50fbdda 277 Use this `path` for fio state generated files.
f80dba8d
MT
278
279Any parameters following the options will be assumed to be job files, unless
280they match a job file parameter. Multiple job files can be listed and each job
281file will be regarded as a separate group. Fio will :option:`stonewall`
282execution between each group.
283
284
285Job file format
286---------------
287
288As previously described, fio accepts one or more job files describing what it is
289supposed to do. The job file format is the classic ini file, where the names
c60ebc45 290enclosed in [] brackets define the job name. You are free to use any ASCII name
f80dba8d
MT
291you want, except *global* which has special meaning. Following the job name is
292a sequence of zero or more parameters, one per line, that define the behavior of
293the job. If the first character in a line is a ';' or a '#', the entire line is
294discarded as a comment.
295
296A *global* section sets defaults for the jobs described in that file. A job may
297override a *global* section parameter, and a job file may even have several
298*global* sections if so desired. A job is only affected by a *global* section
299residing above it.
300
f50fbdda
TK
301The :option:`--cmdhelp` option also lists all options. If used with a `command`
302argument, :option:`--cmdhelp` will detail the given `command`.
f80dba8d
MT
303
304See the `examples/` directory for inspiration on how to write job files. Note
305the copyright and license requirements currently apply to `examples/` files.
306
307So let's look at a really simple job file that defines two processes, each
308randomly reading from a 128MiB file:
309
310.. code-block:: ini
311
312 ; -- start job file --
313 [global]
314 rw=randread
315 size=128m
316
317 [job1]
318
319 [job2]
320
321 ; -- end job file --
322
323As you can see, the job file sections themselves are empty as all the described
324parameters are shared. As no :option:`filename` option is given, fio makes up a
325`filename` for each of the jobs as it sees fit. On the command line, this job
326would look as follows::
327
328$ fio --name=global --rw=randread --size=128m --name=job1 --name=job2
329
330
331Let's look at an example that has a number of processes writing randomly to
332files:
333
334.. code-block:: ini
335
336 ; -- start job file --
337 [random-writers]
338 ioengine=libaio
339 iodepth=4
340 rw=randwrite
341 bs=32k
342 direct=0
343 size=64m
344 numjobs=4
345 ; -- end job file --
346
347Here we have no *global* section, as we only have one job defined anyway. We
348want to use async I/O here, with a depth of 4 for each file. We also increased
349the buffer size used to 32KiB and define numjobs to 4 to fork 4 identical
350jobs. The result is 4 processes each randomly writing to their own 64MiB
351file. Instead of using the above job file, you could have given the parameters
352on the command line. For this case, you would specify::
353
354$ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4
355
356When fio is utilized as a basis of any reasonably large test suite, it might be
357desirable to share a set of standardized settings across multiple job files.
358Instead of copy/pasting such settings, any section may pull in an external
359:file:`filename.fio` file with *include filename* directive, as in the following
360example::
361
362 ; -- start job file including.fio --
363 [global]
364 filename=/tmp/test
365 filesize=1m
366 include glob-include.fio
367
368 [test]
369 rw=randread
370 bs=4k
371 time_based=1
372 runtime=10
373 include test-include.fio
374 ; -- end job file including.fio --
375
376.. code-block:: ini
377
378 ; -- start job file glob-include.fio --
379 thread=1
380 group_reporting=1
381 ; -- end job file glob-include.fio --
382
383.. code-block:: ini
384
385 ; -- start job file test-include.fio --
386 ioengine=libaio
387 iodepth=4
388 ; -- end job file test-include.fio --
389
390Settings pulled into a section apply to that section only (except *global*
391section). Include directives may be nested in that any included file may contain
392further include directive(s). Include files may not contain [] sections.
393
394
395Environment variables
396~~~~~~~~~~~~~~~~~~~~~
397
398Fio also supports environment variable expansion in job files. Any sub-string of
399the form ``${VARNAME}`` as part of an option value (in other words, on the right
400of the '='), will be expanded to the value of the environment variable called
401`VARNAME`. If no such environment variable is defined, or `VARNAME` is the
402empty string, the empty string will be substituted.
403
404As an example, let's look at a sample fio invocation and job file::
405
406$ SIZE=64m NUMJOBS=4 fio jobfile.fio
407
408.. code-block:: ini
409
410 ; -- start job file --
411 [random-writers]
412 rw=randwrite
413 size=${SIZE}
414 numjobs=${NUMJOBS}
415 ; -- end job file --
416
417This will expand to the following equivalent job file at runtime:
418
419.. code-block:: ini
420
421 ; -- start job file --
422 [random-writers]
423 rw=randwrite
424 size=64m
425 numjobs=4
426 ; -- end job file --
427
428Fio ships with a few example job files, you can also look there for inspiration.
429
430Reserved keywords
431~~~~~~~~~~~~~~~~~
432
433Additionally, fio has a set of reserved keywords that will be replaced
434internally with the appropriate value. Those keywords are:
435
436**$pagesize**
437
438 The architecture page size of the running system.
439
440**$mb_memory**
441
442 Megabytes of total memory in the system.
443
444**$ncpus**
445
446 Number of online available CPUs.
447
448These can be used on the command line or in the job file, and will be
449automatically substituted with the current system values when the job is
450run. Simple math is also supported on these keywords, so you can perform actions
451like::
452
b034c0dd 453 size=8*$mb_memory
f80dba8d
MT
454
455and get that properly expanded to 8 times the size of memory in the machine.
456
457
458Job file parameters
459-------------------
460
461This section describes in details each parameter associated with a job. Some
462parameters take an option of a given type, such as an integer or a
463string. Anywhere a numeric value is required, an arithmetic expression may be
464used, provided it is surrounded by parentheses. Supported operators are:
465
466 - addition (+)
467 - subtraction (-)
468 - multiplication (*)
469 - division (/)
470 - modulus (%)
471 - exponentiation (^)
472
473For time values in expressions, units are microseconds by default. This is
474different than for time values not in expressions (not enclosed in
475parentheses). The following types are used:
476
477
478Parameter types
479~~~~~~~~~~~~~~~
480
481**str**
b034c0dd 482 String: A sequence of alphanumeric characters.
f80dba8d
MT
483
484**time**
008d0feb
SW
485 Integer with possible time suffix. Without a unit value is interpreted as
486 seconds unless otherwise specified. Accepts a suffix of 'd' for days, 'h' for
487 hours, 'm' for minutes, 's' for seconds, 'ms' (or 'msec') for milliseconds and
488 'us' (or 'usec') for microseconds. For example, use 10m for 10 minutes.
f80dba8d
MT
489
490.. _int:
491
492**int**
493 Integer. A whole number value, which may contain an integer prefix
494 and an integer suffix:
495
b034c0dd 496 [*integer prefix*] **number** [*integer suffix*]
f80dba8d
MT
497
498 The optional *integer prefix* specifies the number's base. The default
499 is decimal. *0x* specifies hexadecimal.
500
501 The optional *integer suffix* specifies the number's units, and includes an
502 optional unit prefix and an optional unit. For quantities of data, the
947e0fe0
SW
503 default unit is bytes. For quantities of time, the default unit is seconds
504 unless otherwise specified.
f80dba8d 505
9207a0cb 506 With :option:`kb_base`\=1000, fio follows international standards for unit
f80dba8d
MT
507 prefixes. To specify power-of-10 decimal values defined in the
508 International System of Units (SI):
509
eccce61a
TK
510 * *K* -- means kilo (K) or 1000
511 * *M* -- means mega (M) or 1000**2
512 * *G* -- means giga (G) or 1000**3
513 * *T* -- means tera (T) or 1000**4
514 * *P* -- means peta (P) or 1000**5
f80dba8d
MT
515
516 To specify power-of-2 binary values defined in IEC 80000-13:
517
eccce61a
TK
518 * *Ki* -- means kibi (Ki) or 1024
519 * *Mi* -- means mebi (Mi) or 1024**2
520 * *Gi* -- means gibi (Gi) or 1024**3
521 * *Ti* -- means tebi (Ti) or 1024**4
522 * *Pi* -- means pebi (Pi) or 1024**5
f80dba8d 523
9207a0cb 524 With :option:`kb_base`\=1024 (the default), the unit prefixes are opposite
f80dba8d
MT
525 from those specified in the SI and IEC 80000-13 standards to provide
526 compatibility with old scripts. For example, 4k means 4096.
527
528 For quantities of data, an optional unit of 'B' may be included
b8f7e412 529 (e.g., 'kB' is the same as 'k').
f80dba8d
MT
530
531 The *integer suffix* is not case sensitive (e.g., m/mi mean mebi/mega,
532 not milli). 'b' and 'B' both mean byte, not bit.
533
9207a0cb 534 Examples with :option:`kb_base`\=1000:
f80dba8d
MT
535
536 * *4 KiB*: 4096, 4096b, 4096B, 4ki, 4kib, 4kiB, 4Ki, 4KiB
537 * *1 MiB*: 1048576, 1mi, 1024ki
538 * *1 MB*: 1000000, 1m, 1000k
539 * *1 TiB*: 1099511627776, 1ti, 1024gi, 1048576mi
540 * *1 TB*: 1000000000, 1t, 1000m, 1000000k
541
9207a0cb 542 Examples with :option:`kb_base`\=1024 (default):
f80dba8d
MT
543
544 * *4 KiB*: 4096, 4096b, 4096B, 4k, 4kb, 4kB, 4K, 4KB
545 * *1 MiB*: 1048576, 1m, 1024k
546 * *1 MB*: 1000000, 1mi, 1000ki
547 * *1 TiB*: 1099511627776, 1t, 1024g, 1048576m
548 * *1 TB*: 1000000000, 1ti, 1000mi, 1000000ki
549
550 To specify times (units are not case sensitive):
551
552 * *D* -- means days
553 * *H* -- means hours
4502cb42 554 * *M* -- means minutes
f80dba8d
MT
555 * *s* -- or sec means seconds (default)
556 * *ms* -- or *msec* means milliseconds
557 * *us* -- or *usec* means microseconds
558
559 If the option accepts an upper and lower range, use a colon ':' or
560 minus '-' to separate such values. See :ref:`irange <irange>`.
4502cb42
SW
561 If the lower value specified happens to be larger than the upper value
562 the two values are swapped.
f80dba8d
MT
563
564.. _bool:
565
566**bool**
567 Boolean. Usually parsed as an integer, however only defined for
568 true and false (1 and 0).
569
570.. _irange:
571
572**irange**
573 Integer range with suffix. Allows value range to be given, such as
c60ebc45 574 1024-4096. A colon may also be used as the separator, e.g. 1k:4k. If the
f80dba8d
MT
575 option allows two sets of ranges, they can be specified with a ',' or '/'
576 delimiter: 1k-4k/8k-32k. Also see :ref:`int <int>`.
577
578**float_list**
579 A list of floating point numbers, separated by a ':' character.
580
f5c3bcf2
TK
581With the above in mind, here follows the complete list of fio job parameters.
582
f80dba8d
MT
583
584Units
585~~~~~
586
587.. option:: kb_base=int
588
589 Select the interpretation of unit prefixes in input parameters.
590
591 **1000**
592 Inputs comply with IEC 80000-13 and the International
593 System of Units (SI). Use:
594
595 - power-of-2 values with IEC prefixes (e.g., KiB)
596 - power-of-10 values with SI prefixes (e.g., kB)
597
598 **1024**
599 Compatibility mode (default). To avoid breaking old scripts:
600
601 - power-of-2 values with SI prefixes
602 - power-of-10 values with IEC prefixes
603
604 See :option:`bs` for more details on input parameters.
605
606 Outputs always use correct prefixes. Most outputs include both
607 side-by-side, like::
608
609 bw=2383.3kB/s (2327.4KiB/s)
610
611 If only one value is reported, then kb_base selects the one to use:
612
613 **1000** -- SI prefixes
614
615 **1024** -- IEC prefixes
616
617.. option:: unit_base=int
618
619 Base unit for reporting. Allowed values are:
620
621 **0**
622 Use auto-detection (default).
623 **8**
624 Byte based.
625 **1**
626 Bit based.
627
628
f80dba8d
MT
629Job description
630~~~~~~~~~~~~~~~
631
632.. option:: name=str
633
634 ASCII name of the job. This may be used to override the name printed by fio
635 for this job. Otherwise the job name is used. On the command line this
636 parameter has the special purpose of also signaling the start of a new job.
637
638.. option:: description=str
639
640 Text description of the job. Doesn't do anything except dump this text
641 description when this job is run. It's not parsed.
642
643.. option:: loops=int
644
645 Run the specified number of iterations of this job. Used to repeat the same
646 workload a given number of times. Defaults to 1.
647
648.. option:: numjobs=int
649
79591fa9
TK
650 Create the specified number of clones of this job. Each clone of job
651 is spawned as an independent thread or process. May be used to setup a
f80dba8d
MT
652 larger number of threads/processes doing the same thing. Each thread is
653 reported separately; to see statistics for all clones as a whole, use
654 :option:`group_reporting` in conjunction with :option:`new_group`.
a47b697c 655 See :option:`--max-jobs`. Default: 1.
f80dba8d
MT
656
657
658Time related parameters
659~~~~~~~~~~~~~~~~~~~~~~~
660
661.. option:: runtime=time
662
f75ede1d 663 Tell fio to terminate processing after the specified period of time. It
f80dba8d 664 can be quite hard to determine for how long a specified job will run, so
f75ede1d 665 this parameter is handy to cap the total runtime to a given time. When
947e0fe0 666 the unit is omitted, the value is intepreted in seconds.
f80dba8d
MT
667
668.. option:: time_based
669
670 If set, fio will run for the duration of the :option:`runtime` specified
671 even if the file(s) are completely read or written. It will simply loop over
672 the same workload as many times as the :option:`runtime` allows.
673
a881438b 674.. option:: startdelay=irange(time)
f80dba8d 675
947e0fe0
SW
676 Delay the start of job for the specified amount of time. Can be a single
677 value or a range. When given as a range, each thread will choose a value
678 randomly from within the range. Value is in seconds if a unit is omitted.
f80dba8d
MT
679
680.. option:: ramp_time=time
681
682 If set, fio will run the specified workload for this amount of time before
683 logging any performance numbers. Useful for letting performance settle
684 before logging results, thus minimizing the runtime required for stable
685 results. Note that the ``ramp_time`` is considered lead in time for a job,
686 thus it will increase the total runtime if a special timeout or
f75ede1d
SW
687 :option:`runtime` is specified. When the unit is omitted, the value is
688 given in seconds.
f80dba8d
MT
689
690.. option:: clocksource=str
691
692 Use the given clocksource as the base of timing. The supported options are:
693
694 **gettimeofday**
695 :manpage:`gettimeofday(2)`
696
697 **clock_gettime**
698 :manpage:`clock_gettime(2)`
699
700 **cpu**
701 Internal CPU clock source
702
703 cpu is the preferred clocksource if it is reliable, as it is very fast (and
704 fio is heavy on time calls). Fio will automatically use this clocksource if
705 it's supported and considered reliable on the system it is running on,
706 unless another clocksource is specifically set. For x86/x86-64 CPUs, this
707 means supporting TSC Invariant.
708
709.. option:: gtod_reduce=bool
710
711 Enable all of the :manpage:`gettimeofday(2)` reducing options
f75ede1d 712 (:option:`disable_clat`, :option:`disable_slat`, :option:`disable_bw_measurement`) plus
f80dba8d
MT
713 reduce precision of the timeout somewhat to really shrink the
714 :manpage:`gettimeofday(2)` call count. With this option enabled, we only do
715 about 0.4% of the :manpage:`gettimeofday(2)` calls we would have done if all
716 time keeping was enabled.
717
718.. option:: gtod_cpu=int
719
720 Sometimes it's cheaper to dedicate a single thread of execution to just
721 getting the current time. Fio (and databases, for instance) are very
722 intensive on :manpage:`gettimeofday(2)` calls. With this option, you can set
723 one CPU aside for doing nothing but logging current time to a shared memory
724 location. Then the other threads/processes that run I/O workloads need only
725 copy that segment, instead of entering the kernel with a
726 :manpage:`gettimeofday(2)` call. The CPU set aside for doing these time
727 calls will be excluded from other uses. Fio will manually clear it from the
728 CPU mask of other jobs.
729
730
731Target file/device
732~~~~~~~~~~~~~~~~~~
733
734.. option:: directory=str
735
736 Prefix filenames with this directory. Used to place files in a different
737 location than :file:`./`. You can specify a number of directories by
738 separating the names with a ':' character. These directories will be
02dd2689 739 assigned equally distributed to job clones created by :option:`numjobs` as
f80dba8d
MT
740 long as they are using generated filenames. If specific `filename(s)` are
741 set fio will use the first listed directory, and thereby matching the
742 `filename` semantic which generates a file each clone if not specified, but
743 let all clones use the same if set.
744
02dd2689
SW
745 See the :option:`filename` option for information on how to escape "``:``" and
746 "``\``" characters within the directory path itself.
f80dba8d
MT
747
748.. option:: filename=str
749
750 Fio normally makes up a `filename` based on the job name, thread number, and
02dd2689
SW
751 file number (see :option:`filename_format`). If you want to share files
752 between threads in a job or several
79591fa9
TK
753 jobs with fixed file paths, specify a `filename` for each of them to override
754 the default. If the ioengine is file based, you can specify a number of files
755 by separating the names with a ':' colon. So if you wanted a job to open
756 :file:`/dev/sda` and :file:`/dev/sdb` as the two working files, you would use
757 ``filename=/dev/sda:/dev/sdb``. This also means that whenever this option is
758 specified, :option:`nrfiles` is ignored. The size of regular files specified
02dd2689 759 by this option will be :option:`size` divided by number of files unless an
79591fa9
TK
760 explicit size is specified by :option:`filesize`.
761
02dd2689
SW
762 Each colon and backslash in the wanted path must be escaped with a ``\``
763 character. For instance, if the path is :file:`/dev/dsk/foo@3,0:c` then you
764 would use ``filename=/dev/dsk/foo@3,0\:c`` and if the path is
765 :file:`F:\\filename` then you would use ``filename=F\:\\filename``.
766
f80dba8d
MT
767 On Windows, disk devices are accessed as :file:`\\\\.\\PhysicalDrive0` for
768 the first device, :file:`\\\\.\\PhysicalDrive1` for the second etc.
769 Note: Windows and FreeBSD prevent write access to areas
02dd2689
SW
770 of the disk containing in-use data (e.g. filesystems).
771
772 The filename "`-`" is a reserved name, meaning *stdin* or *stdout*. Which
773 of the two depends on the read/write direction set.
f80dba8d
MT
774
775.. option:: filename_format=str
776
777 If sharing multiple files between jobs, it is usually necessary to have fio
778 generate the exact names that you want. By default, fio will name a file
779 based on the default file format specification of
780 :file:`jobname.jobnumber.filenumber`. With this option, that can be
781 customized. Fio will recognize and replace the following keywords in this
782 string:
783
784 **$jobname**
785 The name of the worker thread or process.
786 **$jobnum**
787 The incremental number of the worker thread or process.
788 **$filenum**
789 The incremental number of the file for that worker thread or
790 process.
791
792 To have dependent jobs share a set of files, this option can be set to have
793 fio generate filenames that are shared between the two. For instance, if
794 :file:`testfiles.$filenum` is specified, file number 4 for any job will be
795 named :file:`testfiles.4`. The default of :file:`$jobname.$jobnum.$filenum`
796 will be used if no other format specifier is given.
797
645943c0
JB
798 If you specify a path then the directories will be created up to the
799 main directory for the file. So for example if you specify
800 ``filename_format=a/b/c/$jobnum`` then the directories a/b/c will be
801 created before the file setup part of the job. If you specify
802 :option:`directory` then the path will be relative that directory,
803 otherwise it is treated as the absolute path.
804
f80dba8d
MT
805.. option:: unique_filename=bool
806
807 To avoid collisions between networked clients, fio defaults to prefixing any
808 generated filenames (with a directory specified) with the source of the
809 client connecting. To disable this behavior, set this option to 0.
810
811.. option:: opendir=str
812
813 Recursively open any files below directory `str`.
814
815.. option:: lockfile=str
816
817 Fio defaults to not locking any files before it does I/O to them. If a file
818 or file descriptor is shared, fio can serialize I/O to that file to make the
819 end result consistent. This is usual for emulating real workloads that share
820 files. The lock modes are:
821
822 **none**
823 No locking. The default.
824 **exclusive**
825 Only one thread or process may do I/O at a time, excluding all
826 others.
827 **readwrite**
828 Read-write locking on the file. Many readers may
829 access the file at the same time, but writes get exclusive access.
830
831.. option:: nrfiles=int
832
79591fa9
TK
833 Number of files to use for this job. Defaults to 1. The size of files
834 will be :option:`size` divided by this unless explicit size is specified by
835 :option:`filesize`. Files are created for each thread separately, and each
836 file will have a file number within its name by default, as explained in
837 :option:`filename` section.
838
f80dba8d
MT
839
840.. option:: openfiles=int
841
842 Number of files to keep open at the same time. Defaults to the same as
843 :option:`nrfiles`, can be set smaller to limit the number simultaneous
844 opens.
845
846.. option:: file_service_type=str
847
848 Defines how fio decides which file from a job to service next. The following
849 types are defined:
850
851 **random**
852 Choose a file at random.
853
854 **roundrobin**
855 Round robin over opened files. This is the default.
856
857 **sequential**
858 Finish one file before moving on to the next. Multiple files can
f50fbdda 859 still be open depending on :option:`openfiles`.
f80dba8d
MT
860
861 **zipf**
c60ebc45 862 Use a *Zipf* distribution to decide what file to access.
f80dba8d
MT
863
864 **pareto**
c60ebc45 865 Use a *Pareto* distribution to decide what file to access.
f80dba8d 866
dd3503d3 867 **normal**
c60ebc45 868 Use a *Gaussian* (normal) distribution to decide what file to
f80dba8d
MT
869 access.
870
dd3503d3
SW
871 **gauss**
872 Alias for normal.
873
f80dba8d
MT
874 For *random*, *roundrobin*, and *sequential*, a postfix can be appended to
875 tell fio how many I/Os to issue before switching to a new file. For example,
876 specifying ``file_service_type=random:8`` would cause fio to issue
877 8 I/Os before selecting a new file at random. For the non-uniform
878 distributions, a floating point postfix can be given to influence how the
879 distribution is skewed. See :option:`random_distribution` for a description
880 of how that would work.
881
882.. option:: ioscheduler=str
883
884 Attempt to switch the device hosting the file to the specified I/O scheduler
885 before running.
886
887.. option:: create_serialize=bool
888
889 If true, serialize the file creation for the jobs. This may be handy to
890 avoid interleaving of data files, which may greatly depend on the filesystem
a47b697c 891 used and even the number of processors in the system. Default: true.
f80dba8d
MT
892
893.. option:: create_fsync=bool
894
22413915 895 :manpage:`fsync(2)` the data file after creation. This is the default.
f80dba8d
MT
896
897.. option:: create_on_open=bool
898
730bd7d9
SW
899 If true, don't pre-create files but allow the job's open() to create a file
900 when it's time to do I/O. Default: false -- pre-create all necessary files
901 when the job starts.
f80dba8d
MT
902
903.. option:: create_only=bool
904
905 If true, fio will only run the setup phase of the job. If files need to be
4502cb42 906 laid out or updated on disk, only that will be done -- the actual job contents
a47b697c 907 are not executed. Default: false.
f80dba8d
MT
908
909.. option:: allow_file_create=bool
910
730bd7d9
SW
911 If true, fio is permitted to create files as part of its workload. If this
912 option is false, then fio will error out if
f80dba8d
MT
913 the files it needs to use don't already exist. Default: true.
914
915.. option:: allow_mounted_write=bool
916
c60ebc45 917 If this isn't set, fio will abort jobs that are destructive (e.g. that write)
f80dba8d
MT
918 to what appears to be a mounted device or partition. This should help catch
919 creating inadvertently destructive tests, not realizing that the test will
b1db0375
TK
920 destroy data on the mounted file system. Note that some platforms don't allow
921 writing against a mounted device regardless of this option. Default: false.
f80dba8d
MT
922
923.. option:: pre_read=bool
924
925 If this is given, files will be pre-read into memory before starting the
926 given I/O operation. This will also clear the :option:`invalidate` flag,
927 since it is pointless to pre-read and then drop the cache. This will only
928 work for I/O engines that are seek-able, since they allow you to read the
a47b697c
SW
929 same data multiple times. Thus it will not work on non-seekable I/O engines
930 (e.g. network, splice). Default: false.
f80dba8d
MT
931
932.. option:: unlink=bool
933
934 Unlink the job files when done. Not the default, as repeated runs of that
a47b697c
SW
935 job would then waste time recreating the file set again and again. Default:
936 false.
f80dba8d
MT
937
938.. option:: unlink_each_loop=bool
939
a47b697c 940 Unlink job files after each iteration or loop. Default: false.
f80dba8d
MT
941
942.. option:: zonesize=int
943
944 Divide a file into zones of the specified size. See :option:`zoneskip`.
945
946.. option:: zonerange=int
947
948 Give size of an I/O zone. See :option:`zoneskip`.
949
950.. option:: zoneskip=int
951
952 Skip the specified number of bytes when :option:`zonesize` data has been
953 read. The two zone options can be used to only do I/O on zones of a file.
954
955
956I/O type
957~~~~~~~~
958
959.. option:: direct=bool
960
961 If value is true, use non-buffered I/O. This is usually O_DIRECT. Note that
8e889110 962 OpenBSD and ZFS on Solaris don't support direct I/O. On Windows the synchronous
f80dba8d
MT
963 ioengines don't support direct I/O. Default: false.
964
965.. option:: atomic=bool
966
967 If value is true, attempt to use atomic direct I/O. Atomic writes are
968 guaranteed to be stable once acknowledged by the operating system. Only
969 Linux supports O_ATOMIC right now.
970
971.. option:: buffered=bool
972
973 If value is true, use buffered I/O. This is the opposite of the
974 :option:`direct` option. Defaults to true.
975
976.. option:: readwrite=str, rw=str
977
978 Type of I/O pattern. Accepted values are:
979
980 **read**
981 Sequential reads.
982 **write**
983 Sequential writes.
984 **trim**
985 Sequential trims (Linux block devices only).
f80dba8d
MT
986 **randread**
987 Random reads.
2831be97
SW
988 **randwrite**
989 Random writes.
f80dba8d
MT
990 **randtrim**
991 Random trims (Linux block devices only).
992 **rw,readwrite**
993 Sequential mixed reads and writes.
994 **randrw**
995 Random mixed reads and writes.
996 **trimwrite**
997 Sequential trim+write sequences. Blocks will be trimmed first,
998 then the same blocks will be written to.
999
1000 Fio defaults to read if the option is not specified. For the mixed I/O
1001 types, the default is to split them 50/50. For certain types of I/O the
730bd7d9
SW
1002 result may still be skewed a bit, since the speed may be different.
1003
1004 It is possible to specify the number of I/Os to do before getting a new
1005 offset by appending ``:<nr>`` to the end of the string given. For a
f80dba8d
MT
1006 random read, it would look like ``rw=randread:8`` for passing in an offset
1007 modifier with a value of 8. If the suffix is used with a sequential I/O
730bd7d9
SW
1008 pattern, then the *<nr>* value specified will be **added** to the generated
1009 offset for each I/O turning sequential I/O into sequential I/O with holes.
1010 For instance, using ``rw=write:4k`` will skip 4k for every write. Also see
1011 the :option:`rw_sequencer` option.
f80dba8d
MT
1012
1013.. option:: rw_sequencer=str
1014
1015 If an offset modifier is given by appending a number to the ``rw=<str>``
1016 line, then this option controls how that number modifies the I/O offset
1017 being generated. Accepted values are:
1018
1019 **sequential**
1020 Generate sequential offset.
1021 **identical**
1022 Generate the same offset.
1023
1024 ``sequential`` is only useful for random I/O, where fio would normally
c60ebc45 1025 generate a new random offset for every I/O. If you append e.g. 8 to randread,
007c7be9
SW
1026 you would get a new random offset for every 8 I/Os. The result would be a
1027 seek for only every 8 I/Os, instead of for every I/O. Use ``rw=randread:8``
f80dba8d
MT
1028 to specify that. As sequential I/O is already sequential, setting
1029 ``sequential`` for that would not result in any differences. ``identical``
1030 behaves in a similar fashion, except it sends the same offset 8 number of
1031 times before generating a new offset.
1032
1033.. option:: unified_rw_reporting=bool
1034
1035 Fio normally reports statistics on a per data direction basis, meaning that
1036 reads, writes, and trims are accounted and reported separately. If this
1037 option is set fio sums the results and report them as "mixed" instead.
1038
1039.. option:: randrepeat=bool
1040
1041 Seed the random number generator used for random I/O patterns in a
1042 predictable way so the pattern is repeatable across runs. Default: true.
1043
1044.. option:: allrandrepeat=bool
1045
1046 Seed all random number generators in a predictable way so results are
1047 repeatable across runs. Default: false.
1048
1049.. option:: randseed=int
1050
1051 Seed the random number generators based on this seed value, to be able to
1052 control what sequence of output is being generated. If not set, the random
1053 sequence depends on the :option:`randrepeat` setting.
1054
1055.. option:: fallocate=str
1056
1057 Whether pre-allocation is performed when laying down files.
1058 Accepted values are:
1059
1060 **none**
1061 Do not pre-allocate space.
1062
2c3e17be
SW
1063 **native**
1064 Use a platform's native pre-allocation call but fall back to
1065 **none** behavior if it fails/is not implemented.
1066
f80dba8d
MT
1067 **posix**
1068 Pre-allocate via :manpage:`posix_fallocate(3)`.
1069
1070 **keep**
1071 Pre-allocate via :manpage:`fallocate(2)` with
1072 FALLOC_FL_KEEP_SIZE set.
1073
1074 **0**
1075 Backward-compatible alias for **none**.
1076
1077 **1**
1078 Backward-compatible alias for **posix**.
1079
1080 May not be available on all supported platforms. **keep** is only available
2c3e17be
SW
1081 on Linux. If using ZFS on Solaris this cannot be set to **posix**
1082 because ZFS doesn't support pre-allocation. Default: **native** if any
1083 pre-allocation methods are available, **none** if not.
f80dba8d
MT
1084
1085.. option:: fadvise_hint=str
1086
1087 Use :manpage:`posix_fadvise(2)` to advise the kernel on what I/O patterns
1088 are likely to be issued. Accepted values are:
1089
1090 **0**
1091 Backwards-compatible hint for "no hint".
1092
1093 **1**
1094 Backwards compatible hint for "advise with fio workload type". This
1095 uses **FADV_RANDOM** for a random workload, and **FADV_SEQUENTIAL**
1096 for a sequential workload.
1097
1098 **sequential**
1099 Advise using **FADV_SEQUENTIAL**.
1100
1101 **random**
1102 Advise using **FADV_RANDOM**.
1103
8f4b9f24 1104.. option:: write_hint=str
f80dba8d 1105
8f4b9f24
JA
1106 Use :manpage:`fcntl(2)` to advise the kernel what life time to expect
1107 from a write. Only supported on Linux, as of version 4.13. Accepted
1108 values are:
1109
1110 **none**
1111 No particular life time associated with this file.
1112
1113 **short**
1114 Data written to this file has a short life time.
1115
1116 **medium**
1117 Data written to this file has a medium life time.
1118
1119 **long**
1120 Data written to this file has a long life time.
1121
1122 **extreme**
1123 Data written to this file has a very long life time.
1124
1125 The values are all relative to each other, and no absolute meaning
1126 should be associated with them.
f80dba8d
MT
1127
1128.. option:: offset=int
1129
82dbb8cb 1130 Start I/O at the provided offset in the file, given as either a fixed size in
83c8b093
JF
1131 bytes or a percentage. If a percentage is given, the generated offset will be
1132 aligned to the minimum ``blocksize`` or to the value of ``offset_align`` if
1133 provided. Data before the given offset will not be touched. This
89978a6b
BW
1134 effectively caps the file size at `real_size - offset`. Can be combined with
1135 :option:`size` to constrain the start and end range of the I/O workload.
44bb1142
TK
1136 A percentage can be specified by a number between 1 and 100 followed by '%',
1137 for example, ``offset=20%`` to specify 20%.
f80dba8d 1138
83c8b093
JF
1139.. option:: offset_align=int
1140
1141 If set to non-zero value, the byte offset generated by a percentage ``offset``
1142 is aligned upwards to this value. Defaults to 0 meaning that a percentage
1143 offset is aligned to the minimum block size.
1144
f80dba8d
MT
1145.. option:: offset_increment=int
1146
1147 If this is provided, then the real offset becomes `offset + offset_increment
1148 * thread_number`, where the thread number is a counter that starts at 0 and
1149 is incremented for each sub-job (i.e. when :option:`numjobs` option is
1150 specified). This option is useful if there are several jobs which are
1151 intended to operate on a file in parallel disjoint segments, with even
1152 spacing between the starting points.
1153
1154.. option:: number_ios=int
1155
c60ebc45 1156 Fio will normally perform I/Os until it has exhausted the size of the region
f80dba8d
MT
1157 set by :option:`size`, or if it exhaust the allocated time (or hits an error
1158 condition). With this setting, the range/size can be set independently of
c60ebc45 1159 the number of I/Os to perform. When fio reaches this number, it will exit
f80dba8d
MT
1160 normally and report status. Note that this does not extend the amount of I/O
1161 that will be done, it will only stop fio if this condition is met before
1162 other end-of-job criteria.
1163
1164.. option:: fsync=int
1165
730bd7d9
SW
1166 If writing to a file, issue an :manpage:`fsync(2)` (or its equivalent) of
1167 the dirty data for every number of blocks given. For example, if you give 32
1168 as a parameter, fio will sync the file after every 32 writes issued. If fio is
1169 using non-buffered I/O, we may not sync the file. The exception is the sg
1170 I/O engine, which synchronizes the disk cache anyway. Defaults to 0, which
1171 means fio does not periodically issue and wait for a sync to complete. Also
1172 see :option:`end_fsync` and :option:`fsync_on_close`.
f80dba8d
MT
1173
1174.. option:: fdatasync=int
1175
1176 Like :option:`fsync` but uses :manpage:`fdatasync(2)` to only sync data and
000a5f1c 1177 not metadata blocks. In Windows, FreeBSD, and DragonFlyBSD there is no
730bd7d9
SW
1178 :manpage:`fdatasync(2)` so this falls back to using :manpage:`fsync(2)`.
1179 Defaults to 0, which means fio does not periodically issue and wait for a
1180 data-only sync to complete.
f80dba8d
MT
1181
1182.. option:: write_barrier=int
1183
2831be97 1184 Make every `N-th` write a barrier write.
f80dba8d 1185
f50fbdda 1186.. option:: sync_file_range=str:int
f80dba8d 1187
f50fbdda 1188 Use :manpage:`sync_file_range(2)` for every `int` number of write
f80dba8d
MT
1189 operations. Fio will track range of writes that have happened since the last
1190 :manpage:`sync_file_range(2)` call. `str` can currently be one or more of:
1191
1192 **wait_before**
1193 SYNC_FILE_RANGE_WAIT_BEFORE
1194 **write**
1195 SYNC_FILE_RANGE_WRITE
1196 **wait_after**
1197 SYNC_FILE_RANGE_WAIT_AFTER
1198
1199 So if you do ``sync_file_range=wait_before,write:8``, fio would use
1200 ``SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE`` for every 8
1201 writes. Also see the :manpage:`sync_file_range(2)` man page. This option is
1202 Linux specific.
1203
1204.. option:: overwrite=bool
1205
1206 If true, writes to a file will always overwrite existing data. If the file
1207 doesn't already exist, it will be created before the write phase begins. If
1208 the file exists and is large enough for the specified write phase, nothing
a47b697c 1209 will be done. Default: false.
f80dba8d
MT
1210
1211.. option:: end_fsync=bool
1212
a47b697c
SW
1213 If true, :manpage:`fsync(2)` file contents when a write stage has completed.
1214 Default: false.
f80dba8d
MT
1215
1216.. option:: fsync_on_close=bool
1217
1218 If true, fio will :manpage:`fsync(2)` a dirty file on close. This differs
a47b697c
SW
1219 from :option:`end_fsync` in that it will happen on every file close, not
1220 just at the end of the job. Default: false.
f80dba8d
MT
1221
1222.. option:: rwmixread=int
1223
1224 Percentage of a mixed workload that should be reads. Default: 50.
1225
1226.. option:: rwmixwrite=int
1227
1228 Percentage of a mixed workload that should be writes. If both
1229 :option:`rwmixread` and :option:`rwmixwrite` is given and the values do not
1230 add up to 100%, the latter of the two will be used to override the
1231 first. This may interfere with a given rate setting, if fio is asked to
1232 limit reads or writes to a certain rate. If that is the case, then the
1233 distribution may be skewed. Default: 50.
1234
1235.. option:: random_distribution=str:float[,str:float][,str:float]
1236
1237 By default, fio will use a completely uniform random distribution when asked
1238 to perform random I/O. Sometimes it is useful to skew the distribution in
1239 specific ways, ensuring that some parts of the data is more hot than others.
1240 fio includes the following distribution models:
1241
1242 **random**
1243 Uniform random distribution
1244
1245 **zipf**
1246 Zipf distribution
1247
1248 **pareto**
1249 Pareto distribution
1250
b2f4b559 1251 **normal**
c60ebc45 1252 Normal (Gaussian) distribution
f80dba8d
MT
1253
1254 **zoned**
1255 Zoned random distribution
1256
59466396
JA
1257 **zoned_abs**
1258 Zone absolute random distribution
1259
f80dba8d 1260 When using a **zipf** or **pareto** distribution, an input value is also
f50fbdda 1261 needed to define the access pattern. For **zipf**, this is the `Zipf
c60ebc45 1262 theta`. For **pareto**, it's the `Pareto power`. Fio includes a test
f50fbdda 1263 program, :command:`fio-genzipf`, that can be used visualize what the given input
f80dba8d
MT
1264 values will yield in terms of hit rates. If you wanted to use **zipf** with
1265 a `theta` of 1.2, you would use ``random_distribution=zipf:1.2`` as the
1266 option. If a non-uniform model is used, fio will disable use of the random
b2f4b559
SW
1267 map. For the **normal** distribution, a normal (Gaussian) deviation is
1268 supplied as a value between 0 and 100.
f80dba8d
MT
1269
1270 For a **zoned** distribution, fio supports specifying percentages of I/O
1271 access that should fall within what range of the file or device. For
1272 example, given a criteria of:
1273
f50fbdda
TK
1274 * 60% of accesses should be to the first 10%
1275 * 30% of accesses should be to the next 20%
1276 * 8% of accesses should be to the next 30%
1277 * 2% of accesses should be to the next 40%
f80dba8d
MT
1278
1279 we can define that through zoning of the random accesses. For the above
1280 example, the user would do::
1281
1282 random_distribution=zoned:60/10:30/20:8/30:2/40
1283
59466396
JA
1284 A **zoned_abs** distribution works exactly like the **zoned**, except
1285 that it takes absolute sizes. For example, let's say you wanted to
1286 define access according to the following criteria:
1287
1288 * 60% of accesses should be to the first 20G
1289 * 30% of accesses should be to the next 100G
1290 * 10% of accesses should be to the next 500G
1291
1292 we can define an absolute zoning distribution with:
1293
1294 random_distribution=zoned_abs=60/20G:30/100G:10/500g
1295
6a16ece8
JA
1296 For both **zoned** and **zoned_abs**, fio supports defining up to
1297 256 separate zones.
1298
59466396
JA
1299 Similarly to how :option:`bssplit` works for setting ranges and
1300 percentages of block sizes. Like :option:`bssplit`, it's possible to
1301 specify separate zones for reads, writes, and trims. If just one set
1302 is given, it'll apply to all of them. This goes for both **zoned**
1303 **zoned_abs** distributions.
f80dba8d
MT
1304
1305.. option:: percentage_random=int[,int][,int]
1306
1307 For a random workload, set how big a percentage should be random. This
1308 defaults to 100%, in which case the workload is fully random. It can be set
1309 from anywhere from 0 to 100. Setting it to 0 would make the workload fully
1310 sequential. Any setting in between will result in a random mix of sequential
1311 and random I/O, at the given percentages. Comma-separated values may be
1312 specified for reads, writes, and trims as described in :option:`blocksize`.
1313
1314.. option:: norandommap
1315
1316 Normally fio will cover every block of the file when doing random I/O. If
1317 this option is given, fio will just get a new random offset without looking
1318 at past I/O history. This means that some blocks may not be read or written,
1319 and that some blocks may be read/written more than once. If this option is
1320 used with :option:`verify` and multiple blocksizes (via :option:`bsrange`),
1321 only intact blocks are verified, i.e., partially-overwritten blocks are
1322 ignored.
1323
1324.. option:: softrandommap=bool
1325
1326 See :option:`norandommap`. If fio runs with the random block map enabled and
1327 it fails to allocate the map, if this option is set it will continue without
1328 a random block map. As coverage will not be as complete as with random maps,
1329 this option is disabled by default.
1330
1331.. option:: random_generator=str
1332
f50fbdda 1333 Fio supports the following engines for generating I/O offsets for random I/O:
f80dba8d
MT
1334
1335 **tausworthe**
f50fbdda 1336 Strong 2^88 cycle random number generator.
f80dba8d 1337 **lfsr**
f50fbdda 1338 Linear feedback shift register generator.
f80dba8d 1339 **tausworthe64**
f50fbdda 1340 Strong 64-bit 2^258 cycle random number generator.
f80dba8d
MT
1341
1342 **tausworthe** is a strong random number generator, but it requires tracking
1343 on the side if we want to ensure that blocks are only read or written
f50fbdda 1344 once. **lfsr** guarantees that we never generate the same offset twice, and
f80dba8d 1345 it's also less computationally expensive. It's not a true random generator,
f50fbdda 1346 however, though for I/O purposes it's typically good enough. **lfsr** only
f80dba8d
MT
1347 works with single block sizes, not with workloads that use multiple block
1348 sizes. If used with such a workload, fio may read or write some blocks
1349 multiple times. The default value is **tausworthe**, unless the required
1350 space exceeds 2^32 blocks. If it does, then **tausworthe64** is
1351 selected automatically.
1352
1353
1354Block size
1355~~~~~~~~~~
1356
1357.. option:: blocksize=int[,int][,int], bs=int[,int][,int]
1358
1359 The block size in bytes used for I/O units. Default: 4096. A single value
1360 applies to reads, writes, and trims. Comma-separated values may be
1361 specified for reads, writes, and trims. A value not terminated in a comma
1362 applies to subsequent types.
1363
1364 Examples:
1365
1366 **bs=256k**
1367 means 256k for reads, writes and trims.
1368
1369 **bs=8k,32k**
1370 means 8k for reads, 32k for writes and trims.
1371
1372 **bs=8k,32k,**
1373 means 8k for reads, 32k for writes, and default for trims.
1374
1375 **bs=,8k**
1376 means default for reads, 8k for writes and trims.
1377
1378 **bs=,8k,**
b443ae44 1379 means default for reads, 8k for writes, and default for trims.
f80dba8d
MT
1380
1381.. option:: blocksize_range=irange[,irange][,irange], bsrange=irange[,irange][,irange]
1382
1383 A range of block sizes in bytes for I/O units. The issued I/O unit will
1384 always be a multiple of the minimum size, unless
1385 :option:`blocksize_unaligned` is set.
1386
1387 Comma-separated ranges may be specified for reads, writes, and trims as
1388 described in :option:`blocksize`.
1389
1390 Example: ``bsrange=1k-4k,2k-8k``.
1391
1392.. option:: bssplit=str[,str][,str]
1393
6a16ece8
JA
1394 Sometimes you want even finer grained control of the block sizes
1395 issued, not just an even split between them. This option allows you to
1396 weight various block sizes, so that you are able to define a specific
1397 amount of block sizes issued. The format for this option is::
f80dba8d
MT
1398
1399 bssplit=blocksize/percentage:blocksize/percentage
1400
6a16ece8
JA
1401 for as many block sizes as needed. So if you want to define a workload
1402 that has 50% 64k blocks, 10% 4k blocks, and 40% 32k blocks, you would
1403 write::
f80dba8d
MT
1404
1405 bssplit=4k/10:64k/50:32k/40
1406
6a16ece8
JA
1407 Ordering does not matter. If the percentage is left blank, fio will
1408 fill in the remaining values evenly. So a bssplit option like this one::
f80dba8d
MT
1409
1410 bssplit=4k/50:1k/:32k/
1411
6a16ece8
JA
1412 would have 50% 4k ios, and 25% 1k and 32k ios. The percentages always
1413 add up to 100, if bssplit is given a range that adds up to more, it
1414 will error out.
f80dba8d
MT
1415
1416 Comma-separated values may be specified for reads, writes, and trims as
1417 described in :option:`blocksize`.
1418
6a16ece8
JA
1419 If you want a workload that has 50% 2k reads and 50% 4k reads, while
1420 having 90% 4k writes and 10% 8k writes, you would specify::
f80dba8d
MT
1421
1422 bssplit=2k/50:4k/50,4k/90,8k/10
1423
6a16ece8
JA
1424 Fio supports defining up to 64 different weights for each data
1425 direction.
1426
f80dba8d
MT
1427.. option:: blocksize_unaligned, bs_unaligned
1428
1429 If set, fio will issue I/O units with any size within
1430 :option:`blocksize_range`, not just multiples of the minimum size. This
1431 typically won't work with direct I/O, as that normally requires sector
1432 alignment.
1433
589e88b7 1434.. option:: bs_is_seq_rand=bool
f80dba8d
MT
1435
1436 If this option is set, fio will use the normal read,write blocksize settings
1437 as sequential,random blocksize settings instead. Any random read or write
1438 will use the WRITE blocksize settings, and any sequential read or write will
1439 use the READ blocksize settings.
1440
1441.. option:: blockalign=int[,int][,int], ba=int[,int][,int]
1442
1443 Boundary to which fio will align random I/O units. Default:
1444 :option:`blocksize`. Minimum alignment is typically 512b for using direct
1445 I/O, though it usually depends on the hardware block size. This option is
1446 mutually exclusive with using a random map for files, so it will turn off
1447 that option. Comma-separated values may be specified for reads, writes, and
1448 trims as described in :option:`blocksize`.
1449
1450
1451Buffers and memory
1452~~~~~~~~~~~~~~~~~~
1453
1454.. option:: zero_buffers
1455
1456 Initialize buffers with all zeros. Default: fill buffers with random data.
1457
1458.. option:: refill_buffers
1459
1460 If this option is given, fio will refill the I/O buffers on every
72592780
SW
1461 submit. Only makes sense if :option:`zero_buffers` isn't specified,
1462 naturally. Defaults to being unset i.e., the buffer is only filled at
1463 init time and the data in it is reused when possible but if any of
1464 :option:`verify`, :option:`buffer_compress_percentage` or
1465 :option:`dedupe_percentage` are enabled then `refill_buffers` is also
1466 automatically enabled.
f80dba8d
MT
1467
1468.. option:: scramble_buffers=bool
1469
1470 If :option:`refill_buffers` is too costly and the target is using data
1471 deduplication, then setting this option will slightly modify the I/O buffer
1472 contents to defeat normal de-dupe attempts. This is not enough to defeat
1473 more clever block compression attempts, but it will stop naive dedupe of
1474 blocks. Default: true.
1475
1476.. option:: buffer_compress_percentage=int
1477
72592780
SW
1478 If this is set, then fio will attempt to provide I/O buffer content
1479 (on WRITEs) that compresses to the specified level. Fio does this by
1480 providing a mix of random data followed by fixed pattern data. The
1481 fixed pattern is either zeros, or the pattern specified by
1482 :option:`buffer_pattern`. If the `buffer_pattern` option is used, it
1483 might skew the compression ratio slightly. Setting
1484 `buffer_compress_percentage` to a value other than 100 will also
1485 enable :option:`refill_buffers` in order to reduce the likelihood that
1486 adjacent blocks are so similar that they over compress when seen
1487 together. See :option:`buffer_compress_chunk` for how to set a finer or
1488 coarser granularity for the random/fixed data region. Defaults to unset
1489 i.e., buffer data will not adhere to any compression level.
f80dba8d
MT
1490
1491.. option:: buffer_compress_chunk=int
1492
72592780
SW
1493 This setting allows fio to manage how big the random/fixed data region
1494 is when using :option:`buffer_compress_percentage`. When
1495 `buffer_compress_chunk` is set to some non-zero value smaller than the
1496 block size, fio can repeat the random/fixed region throughout the I/O
1497 buffer at the specified interval (which particularly useful when
1498 bigger block sizes are used for a job). When set to 0, fio will use a
1499 chunk size that matches the block size resulting in a single
1500 random/fixed region within the I/O buffer. Defaults to 512. When the
1501 unit is omitted, the value is interpreted in bytes.
f80dba8d
MT
1502
1503.. option:: buffer_pattern=str
1504
a1554f65
SB
1505 If set, fio will fill the I/O buffers with this pattern or with the contents
1506 of a file. If not set, the contents of I/O buffers are defined by the other
1507 options related to buffer contents. The setting can be any pattern of bytes,
1508 and can be prefixed with 0x for hex values. It may also be a string, where
1509 the string must then be wrapped with ``""``. Or it may also be a filename,
1510 where the filename must be wrapped with ``''`` in which case the file is
1511 opened and read. Note that not all the file contents will be read if that
1512 would cause the buffers to overflow. So, for example::
1513
1514 buffer_pattern='filename'
1515
1516 or::
f80dba8d
MT
1517
1518 buffer_pattern="abcd"
1519
1520 or::
1521
1522 buffer_pattern=-12
1523
1524 or::
1525
1526 buffer_pattern=0xdeadface
1527
1528 Also you can combine everything together in any order::
1529
a1554f65 1530 buffer_pattern=0xdeadface"abcd"-12'filename'
f80dba8d
MT
1531
1532.. option:: dedupe_percentage=int
1533
1534 If set, fio will generate this percentage of identical buffers when
1535 writing. These buffers will be naturally dedupable. The contents of the
1536 buffers depend on what other buffer compression settings have been set. It's
1537 possible to have the individual buffers either fully compressible, or not at
72592780
SW
1538 all -- this option only controls the distribution of unique buffers. Setting
1539 this option will also enable :option:`refill_buffers` to prevent every buffer
1540 being identical.
f80dba8d
MT
1541
1542.. option:: invalidate=bool
1543
730bd7d9
SW
1544 Invalidate the buffer/page cache parts of the files to be used prior to
1545 starting I/O if the platform and file type support it. Defaults to true.
21c1b29e
TK
1546 This will be ignored if :option:`pre_read` is also specified for the
1547 same job.
f80dba8d
MT
1548
1549.. option:: sync=bool
1550
1551 Use synchronous I/O for buffered writes. For the majority of I/O engines,
1552 this means using O_SYNC. Default: false.
1553
1554.. option:: iomem=str, mem=str
1555
1556 Fio can use various types of memory as the I/O unit buffer. The allowed
1557 values are:
1558
1559 **malloc**
1560 Use memory from :manpage:`malloc(3)` as the buffers. Default memory
1561 type.
1562
1563 **shm**
1564 Use shared memory as the buffers. Allocated through
1565 :manpage:`shmget(2)`.
1566
1567 **shmhuge**
1568 Same as shm, but use huge pages as backing.
1569
1570 **mmap**
22413915 1571 Use :manpage:`mmap(2)` to allocate buffers. May either be anonymous memory, or can
f80dba8d
MT
1572 be file backed if a filename is given after the option. The format
1573 is `mem=mmap:/path/to/file`.
1574
1575 **mmaphuge**
1576 Use a memory mapped huge file as the buffer backing. Append filename
1577 after mmaphuge, ala `mem=mmaphuge:/hugetlbfs/file`.
1578
1579 **mmapshared**
1580 Same as mmap, but use a MMAP_SHARED mapping.
1581
03553853
YR
1582 **cudamalloc**
1583 Use GPU memory as the buffers for GPUDirect RDMA benchmark.
f50fbdda 1584 The :option:`ioengine` must be `rdma`.
03553853 1585
f80dba8d
MT
1586 The area allocated is a function of the maximum allowed bs size for the job,
1587 multiplied by the I/O depth given. Note that for **shmhuge** and
1588 **mmaphuge** to work, the system must have free huge pages allocated. This
1589 can normally be checked and set by reading/writing
1590 :file:`/proc/sys/vm/nr_hugepages` on a Linux system. Fio assumes a huge page
1591 is 4MiB in size. So to calculate the number of huge pages you need for a
1592 given job file, add up the I/O depth of all jobs (normally one unless
1593 :option:`iodepth` is used) and multiply by the maximum bs set. Then divide
1594 that number by the huge page size. You can see the size of the huge pages in
1595 :file:`/proc/meminfo`. If no huge pages are allocated by having a non-zero
1596 number in `nr_hugepages`, using **mmaphuge** or **shmhuge** will fail. Also
1597 see :option:`hugepage-size`.
1598
1599 **mmaphuge** also needs to have hugetlbfs mounted and the file location
1600 should point there. So if it's mounted in :file:`/huge`, you would use
1601 `mem=mmaphuge:/huge/somefile`.
1602
f50fbdda 1603.. option:: iomem_align=int, mem_align=int
f80dba8d
MT
1604
1605 This indicates the memory alignment of the I/O memory buffers. Note that
1606 the given alignment is applied to the first I/O unit buffer, if using
1607 :option:`iodepth` the alignment of the following buffers are given by the
1608 :option:`bs` used. In other words, if using a :option:`bs` that is a
1609 multiple of the page sized in the system, all buffers will be aligned to
1610 this value. If using a :option:`bs` that is not page aligned, the alignment
1611 of subsequent I/O memory buffers is the sum of the :option:`iomem_align` and
1612 :option:`bs` used.
1613
1614.. option:: hugepage-size=int
1615
1616 Defines the size of a huge page. Must at least be equal to the system
1617 setting, see :file:`/proc/meminfo`. Defaults to 4MiB. Should probably
1618 always be a multiple of megabytes, so using ``hugepage-size=Xm`` is the
1619 preferred way to set this to avoid setting a non-pow-2 bad value.
1620
1621.. option:: lockmem=int
1622
1623 Pin the specified amount of memory with :manpage:`mlock(2)`. Can be used to
1624 simulate a smaller amount of memory. The amount specified is per worker.
1625
1626
1627I/O size
1628~~~~~~~~
1629
1630.. option:: size=int
1631
79591fa9
TK
1632 The total size of file I/O for each thread of this job. Fio will run until
1633 this many bytes has been transferred, unless runtime is limited by other options
1634 (such as :option:`runtime`, for instance, or increased/decreased by :option:`io_size`).
1635 Fio will divide this size between the available files determined by options
1636 such as :option:`nrfiles`, :option:`filename`, unless :option:`filesize` is
1637 specified by the job. If the result of division happens to be 0, the size is
c4aa2d08 1638 set to the physical size of the given files or devices if they exist.
79591fa9 1639 If this option is not specified, fio will use the full size of the given
f80dba8d
MT
1640 files or devices. If the files do not exist, size must be given. It is also
1641 possible to give size as a percentage between 1 and 100. If ``size=20%`` is
1642 given, fio will use 20% of the full size of the given files or devices.
9d25d068
SW
1643 Can be combined with :option:`offset` to constrain the start and end range
1644 that I/O will be done within.
f80dba8d
MT
1645
1646.. option:: io_size=int, io_limit=int
1647
1648 Normally fio operates within the region set by :option:`size`, which means
1649 that the :option:`size` option sets both the region and size of I/O to be
1650 performed. Sometimes that is not what you want. With this option, it is
1651 possible to define just the amount of I/O that fio should do. For instance,
1652 if :option:`size` is set to 20GiB and :option:`io_size` is set to 5GiB, fio
1653 will perform I/O within the first 20GiB but exit when 5GiB have been
1654 done. The opposite is also possible -- if :option:`size` is set to 20GiB,
1655 and :option:`io_size` is set to 40GiB, then fio will do 40GiB of I/O within
1656 the 0..20GiB region.
1657
7fdd97ca 1658.. option:: filesize=irange(int)
f80dba8d
MT
1659
1660 Individual file sizes. May be a range, in which case fio will select sizes
1661 for files at random within the given range and limited to :option:`size` in
1662 total (if that is given). If not given, each created file is the same size.
79591fa9
TK
1663 This option overrides :option:`size` in terms of file size, which means
1664 this value is used as a fixed size or possible range of each file.
f80dba8d
MT
1665
1666.. option:: file_append=bool
1667
1668 Perform I/O after the end of the file. Normally fio will operate within the
1669 size of a file. If this option is set, then fio will append to the file
1670 instead. This has identical behavior to setting :option:`offset` to the size
1671 of a file. This option is ignored on non-regular files.
1672
1673.. option:: fill_device=bool, fill_fs=bool
1674
1675 Sets size to something really large and waits for ENOSPC (no space left on
1676 device) as the terminating condition. Only makes sense with sequential
1677 write. For a read workload, the mount point will be filled first then I/O
1678 started on the result. This option doesn't make sense if operating on a raw
1679 device node, since the size of that is already known by the file system.
1680 Additionally, writing beyond end-of-device will not return ENOSPC there.
1681
1682
1683I/O engine
1684~~~~~~~~~~
1685
1686.. option:: ioengine=str
1687
1688 Defines how the job issues I/O to the file. The following types are defined:
1689
1690 **sync**
1691 Basic :manpage:`read(2)` or :manpage:`write(2)`
1692 I/O. :manpage:`lseek(2)` is used to position the I/O location.
54227e6b 1693 See :option:`fsync` and :option:`fdatasync` for syncing write I/Os.
f80dba8d
MT
1694
1695 **psync**
1696 Basic :manpage:`pread(2)` or :manpage:`pwrite(2)` I/O. Default on
1697 all supported operating systems except for Windows.
1698
1699 **vsync**
1700 Basic :manpage:`readv(2)` or :manpage:`writev(2)` I/O. Will emulate
c60ebc45 1701 queuing by coalescing adjacent I/Os into a single submission.
f80dba8d
MT
1702
1703 **pvsync**
1704 Basic :manpage:`preadv(2)` or :manpage:`pwritev(2)` I/O.
1705
1706 **pvsync2**
1707 Basic :manpage:`preadv2(2)` or :manpage:`pwritev2(2)` I/O.
1708
1709 **libaio**
1710 Linux native asynchronous I/O. Note that Linux may only support
22413915 1711 queued behavior with non-buffered I/O (set ``direct=1`` or
f80dba8d
MT
1712 ``buffered=0``).
1713 This engine defines engine specific options.
1714
1715 **posixaio**
1716 POSIX asynchronous I/O using :manpage:`aio_read(3)` and
1717 :manpage:`aio_write(3)`.
1718
1719 **solarisaio**
1720 Solaris native asynchronous I/O.
1721
1722 **windowsaio**
1723 Windows native asynchronous I/O. Default on Windows.
1724
1725 **mmap**
1726 File is memory mapped with :manpage:`mmap(2)` and data copied
1727 to/from using :manpage:`memcpy(3)`.
1728
1729 **splice**
1730 :manpage:`splice(2)` is used to transfer the data and
1731 :manpage:`vmsplice(2)` to transfer data from user space to the
1732 kernel.
1733
1734 **sg**
1735 SCSI generic sg v3 I/O. May either be synchronous using the SG_IO
1736 ioctl, or if the target is an sg character device we use
1737 :manpage:`read(2)` and :manpage:`write(2)` for asynchronous
f50fbdda
TK
1738 I/O. Requires :option:`filename` option to specify either block or
1739 character devices.
f80dba8d
MT
1740
1741 **null**
1742 Doesn't transfer any data, just pretends to. This is mainly used to
1743 exercise fio itself and for debugging/testing purposes.
1744
1745 **net**
1746 Transfer over the network to given ``host:port``. Depending on the
1747 :option:`protocol` used, the :option:`hostname`, :option:`port`,
1748 :option:`listen` and :option:`filename` options are used to specify
1749 what sort of connection to make, while the :option:`protocol` option
1750 determines which protocol will be used. This engine defines engine
1751 specific options.
1752
1753 **netsplice**
1754 Like **net**, but uses :manpage:`splice(2)` and
1755 :manpage:`vmsplice(2)` to map data and send/receive.
1756 This engine defines engine specific options.
1757
1758 **cpuio**
1759 Doesn't transfer any data, but burns CPU cycles according to the
1760 :option:`cpuload` and :option:`cpuchunks` options. Setting
9207a0cb 1761 :option:`cpuload`\=85 will cause that job to do nothing but burn 85%
71aa48eb 1762 of the CPU. In case of SMP machines, use :option:`numjobs`\=<nr_of_cpu>
f50fbdda 1763 to get desired CPU usage, as the cpuload only loads a
f80dba8d
MT
1764 single CPU at the desired rate. A job never finishes unless there is
1765 at least one non-cpuio job.
1766
1767 **guasi**
1768 The GUASI I/O engine is the Generic Userspace Asyncronous Syscall
1769 Interface approach to async I/O. See
1770
1771 http://www.xmailserver.org/guasi-lib.html
1772
1773 for more info on GUASI.
1774
1775 **rdma**
1776 The RDMA I/O engine supports both RDMA memory semantics
1777 (RDMA_WRITE/RDMA_READ) and channel semantics (Send/Recv) for the
609ac152
SB
1778 InfiniBand, RoCE and iWARP protocols. This engine defines engine
1779 specific options.
f80dba8d
MT
1780
1781 **falloc**
1782 I/O engine that does regular fallocate to simulate data transfer as
1783 fio ioengine.
1784
1785 DDIR_READ
1786 does fallocate(,mode = FALLOC_FL_KEEP_SIZE,).
1787
1788 DDIR_WRITE
1789 does fallocate(,mode = 0).
1790
1791 DDIR_TRIM
1792 does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE).
1793
761cd093
SW
1794 **ftruncate**
1795 I/O engine that sends :manpage:`ftruncate(2)` operations in response
1796 to write (DDIR_WRITE) events. Each ftruncate issued sets the file's
f50fbdda 1797 size to the current block offset. :option:`blocksize` is ignored.
761cd093 1798
f80dba8d
MT
1799 **e4defrag**
1800 I/O engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate
1801 defragment activity in request to DDIR_WRITE event.
1802
1803 **rbd**
1804 I/O engine supporting direct access to Ceph Rados Block Devices
1805 (RBD) via librbd without the need to use the kernel rbd driver. This
1806 ioengine defines engine specific options.
1807
1808 **gfapi**
ac8ca2af
SW
1809 Using GlusterFS libgfapi sync interface to direct access to
1810 GlusterFS volumes without having to go through FUSE. This ioengine
f80dba8d
MT
1811 defines engine specific options.
1812
1813 **gfapi_async**
ac8ca2af
SW
1814 Using GlusterFS libgfapi async interface to direct access to
1815 GlusterFS volumes without having to go through FUSE. This ioengine
f80dba8d
MT
1816 defines engine specific options.
1817
1818 **libhdfs**
f50fbdda 1819 Read and write through Hadoop (HDFS). The :option:`filename` option
f80dba8d
MT
1820 is used to specify host,port of the hdfs name-node to connect. This
1821 engine interprets offsets a little differently. In HDFS, files once
e25c0c91
SW
1822 created cannot be modified so random writes are not possible. To
1823 imitate this the libhdfs engine expects a bunch of small files to be
1824 created over HDFS and will randomly pick a file from them
1825 based on the offset generated by fio backend (see the example
f80dba8d 1826 job file to create such files, use ``rw=write`` option). Please
e25c0c91
SW
1827 note, it may be necessary to set environment variables to work
1828 with HDFS/libhdfs properly. Each job uses its own connection to
f80dba8d
MT
1829 HDFS.
1830
1831 **mtd**
1832 Read, write and erase an MTD character device (e.g.,
1833 :file:`/dev/mtd0`). Discards are treated as erases. Depending on the
1834 underlying device type, the I/O may have to go in a certain pattern,
1835 e.g., on NAND, writing sequentially to erase blocks and discarding
c298ee71 1836 before overwriting. The `trimwrite` mode works well for this
f80dba8d
MT
1837 constraint.
1838
1839 **pmemblk**
1840 Read and write using filesystem DAX to a file on a filesystem
1841 mounted with DAX on a persistent memory device through the NVML
1842 libpmemblk library.
1843
1844 **dev-dax**
1845 Read and write using device DAX to a persistent memory device (e.g.,
1846 /dev/dax0.0) through the NVML libpmem library.
1847
1848 **external**
1849 Prefix to specify loading an external I/O engine object file. Append
c60ebc45 1850 the engine filename, e.g. ``ioengine=external:/tmp/foo.o`` to load
d243fd6d
TK
1851 ioengine :file:`foo.o` in :file:`/tmp`. The path can be either
1852 absolute or relative. See :file:`engines/skeleton_external.c` for
1853 details of writing an external I/O engine.
f80dba8d 1854
1216cc5a 1855 **filecreate**
b71968b1 1856 Simply create the files and do no I/O to them. You still need to
1216cc5a 1857 set `filesize` so that all the accounting still occurs, but no
b71968b1 1858 actual I/O will be done other than creating the file.
f80dba8d 1859
ae0db592
TI
1860 **libpmem**
1861 Read and write using mmap I/O to a file on a filesystem
1862 mounted with DAX on a persistent memory device through the NVML
1863 libpmem library.
1864
f80dba8d
MT
1865I/O engine specific parameters
1866~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1867
1868In addition, there are some parameters which are only valid when a specific
f50fbdda
TK
1869:option:`ioengine` is in use. These are used identically to normal parameters,
1870with the caveat that when used on the command line, they must come after the
f80dba8d
MT
1871:option:`ioengine` that defines them is selected.
1872
1873.. option:: userspace_reap : [libaio]
1874
1875 Normally, with the libaio engine in use, fio will use the
1876 :manpage:`io_getevents(2)` system call to reap newly returned events. With
1877 this flag turned on, the AIO ring will be read directly from user-space to
1878 reap events. The reaping mode is only enabled when polling for a minimum of
c60ebc45 1879 0 events (e.g. when :option:`iodepth_batch_complete` `=0`).
f80dba8d 1880
9d25d068 1881.. option:: hipri : [pvsync2]
f80dba8d
MT
1882
1883 Set RWF_HIPRI on I/O, indicating to the kernel that it's of higher priority
1884 than normal.
1885
a0679ce5
SB
1886.. option:: hipri_percentage : [pvsync2]
1887
f50fbdda 1888 When hipri is set this determines the probability of a pvsync2 I/O being high
a0679ce5
SB
1889 priority. The default is 100%.
1890
f80dba8d
MT
1891.. option:: cpuload=int : [cpuio]
1892
da19cdb4
TK
1893 Attempt to use the specified percentage of CPU cycles. This is a mandatory
1894 option when using cpuio I/O engine.
f80dba8d
MT
1895
1896.. option:: cpuchunks=int : [cpuio]
1897
1898 Split the load into cycles of the given time. In microseconds.
1899
1900.. option:: exit_on_io_done=bool : [cpuio]
1901
1902 Detect when I/O threads are done, then exit.
1903
f80dba8d
MT
1904.. option:: namenode=str : [libhdfs]
1905
22413915 1906 The hostname or IP address of a HDFS cluster namenode to contact.
f80dba8d
MT
1907
1908.. option:: port=int
1909
f50fbdda
TK
1910 [libhdfs]
1911
1912 The listening port of the HFDS cluster namenode.
1913
f80dba8d
MT
1914 [netsplice], [net]
1915
1916 The TCP or UDP port to bind to or connect to. If this is used with
1917 :option:`numjobs` to spawn multiple instances of the same job type, then
1918 this will be the starting port number since fio will use a range of
1919 ports.
1920
609ac152
SB
1921 [rdma]
1922
1923 The port to use for RDMA-CM communication. This should be the same value
1924 on the client and the server side.
1925
1926.. option:: hostname=str : [netsplice] [net] [rdma]
f80dba8d 1927
609ac152
SB
1928 The hostname or IP address to use for TCP, UDP or RDMA-CM based I/O. If the job
1929 is a TCP listener or UDP reader, the hostname is not used and must be omitted
f50fbdda 1930 unless it is a valid UDP multicast address.
f80dba8d
MT
1931
1932.. option:: interface=str : [netsplice] [net]
1933
1934 The IP address of the network interface used to send or receive UDP
1935 multicast.
1936
1937.. option:: ttl=int : [netsplice] [net]
1938
1939 Time-to-live value for outgoing UDP multicast packets. Default: 1.
1940
1941.. option:: nodelay=bool : [netsplice] [net]
1942
1943 Set TCP_NODELAY on TCP connections.
1944
f50fbdda 1945.. option:: protocol=str, proto=str : [netsplice] [net]
f80dba8d
MT
1946
1947 The network protocol to use. Accepted values are:
1948
1949 **tcp**
1950 Transmission control protocol.
1951 **tcpv6**
1952 Transmission control protocol V6.
1953 **udp**
1954 User datagram protocol.
1955 **udpv6**
1956 User datagram protocol V6.
1957 **unix**
1958 UNIX domain socket.
1959
1960 When the protocol is TCP or UDP, the port must also be given, as well as the
1961 hostname if the job is a TCP listener or UDP reader. For unix sockets, the
f50fbdda 1962 normal :option:`filename` option should be used and the port is invalid.
f80dba8d 1963
e9184ec1 1964.. option:: listen : [netsplice] [net]
f80dba8d
MT
1965
1966 For TCP network connections, tell fio to listen for incoming connections
1967 rather than initiating an outgoing connection. The :option:`hostname` must
1968 be omitted if this option is used.
1969
e9184ec1 1970.. option:: pingpong : [netsplice] [net]
f80dba8d
MT
1971
1972 Normally a network writer will just continue writing data, and a network
1973 reader will just consume packages. If ``pingpong=1`` is set, a writer will
1974 send its normal payload to the reader, then wait for the reader to send the
1975 same payload back. This allows fio to measure network latencies. The
1976 submission and completion latencies then measure local time spent sending or
1977 receiving, and the completion latency measures how long it took for the
1978 other end to receive and send back. For UDP multicast traffic
1979 ``pingpong=1`` should only be set for a single reader when multiple readers
1980 are listening to the same address.
1981
e9184ec1 1982.. option:: window_size : [netsplice] [net]
f80dba8d
MT
1983
1984 Set the desired socket buffer size for the connection.
1985
e9184ec1 1986.. option:: mss : [netsplice] [net]
f80dba8d
MT
1987
1988 Set the TCP maximum segment size (TCP_MAXSEG).
1989
1990.. option:: donorname=str : [e4defrag]
1991
730bd7d9 1992 File will be used as a block donor (swap extents between files).
f80dba8d
MT
1993
1994.. option:: inplace=int : [e4defrag]
1995
1996 Configure donor file blocks allocation strategy:
1997
1998 **0**
1999 Default. Preallocate donor's file on init.
2000 **1**
2b455dbf 2001 Allocate space immediately inside defragment event, and free right
f80dba8d
MT
2002 after event.
2003
2004.. option:: clustername=str : [rbd]
2005
2006 Specifies the name of the Ceph cluster.
2007
2008.. option:: rbdname=str : [rbd]
2009
2010 Specifies the name of the RBD.
2011
2012.. option:: pool=str : [rbd]
2013
2014 Specifies the name of the Ceph pool containing RBD.
2015
2016.. option:: clientname=str : [rbd]
2017
2018 Specifies the username (without the 'client.' prefix) used to access the
2019 Ceph cluster. If the *clustername* is specified, the *clientname* shall be
2020 the full *type.id* string. If no type. prefix is given, fio will add
2021 'client.' by default.
2022
2023.. option:: skip_bad=bool : [mtd]
2024
2025 Skip operations against known bad blocks.
2026
2027.. option:: hdfsdirectory : [libhdfs]
2028
2029 libhdfs will create chunk in this HDFS directory.
2030
2031.. option:: chunk_size : [libhdfs]
2032
2b455dbf 2033 The size of the chunk to use for each file.
f80dba8d 2034
609ac152
SB
2035.. option:: verb=str : [rdma]
2036
2037 The RDMA verb to use on this side of the RDMA ioengine connection. Valid
2038 values are write, read, send and recv. These correspond to the equivalent
2039 RDMA verbs (e.g. write = rdma_write etc.). Note that this only needs to be
2040 specified on the client side of the connection. See the examples folder.
2041
2042.. option:: bindname=str : [rdma]
2043
2044 The name to use to bind the local RDMA-CM connection to a local RDMA device.
2045 This could be a hostname or an IPv4 or IPv6 address. On the server side this
2046 will be passed into the rdma_bind_addr() function and on the client site it
2047 will be used in the rdma_resolve_add() function. This can be useful when
2048 multiple paths exist between the client and the server or in certain loopback
2049 configurations.
f80dba8d
MT
2050
2051I/O depth
2052~~~~~~~~~
2053
2054.. option:: iodepth=int
2055
2056 Number of I/O units to keep in flight against the file. Note that
2057 increasing *iodepth* beyond 1 will not affect synchronous ioengines (except
c60ebc45 2058 for small degrees when :option:`verify_async` is in use). Even async
f80dba8d
MT
2059 engines may impose OS restrictions causing the desired depth not to be
2060 achieved. This may happen on Linux when using libaio and not setting
9207a0cb 2061 :option:`direct`\=1, since buffered I/O is not async on that OS. Keep an
f80dba8d
MT
2062 eye on the I/O depth distribution in the fio output to verify that the
2063 achieved depth is as expected. Default: 1.
2064
2065.. option:: iodepth_batch_submit=int, iodepth_batch=int
2066
2067 This defines how many pieces of I/O to submit at once. It defaults to 1
2068 which means that we submit each I/O as soon as it is available, but can be
2069 raised to submit bigger batches of I/O at the time. If it is set to 0 the
2070 :option:`iodepth` value will be used.
2071
2072.. option:: iodepth_batch_complete_min=int, iodepth_batch_complete=int
2073
2074 This defines how many pieces of I/O to retrieve at once. It defaults to 1
2075 which means that we'll ask for a minimum of 1 I/O in the retrieval process
2076 from the kernel. The I/O retrieval will go on until we hit the limit set by
2077 :option:`iodepth_low`. If this variable is set to 0, then fio will always
2078 check for completed events before queuing more I/O. This helps reduce I/O
2079 latency, at the cost of more retrieval system calls.
2080
2081.. option:: iodepth_batch_complete_max=int
2082
2083 This defines maximum pieces of I/O to retrieve at once. This variable should
9207a0cb 2084 be used along with :option:`iodepth_batch_complete_min`\=int variable,
f80dba8d 2085 specifying the range of min and max amount of I/O which should be
730bd7d9 2086 retrieved. By default it is equal to the :option:`iodepth_batch_complete_min`
f80dba8d
MT
2087 value.
2088
2089 Example #1::
2090
2091 iodepth_batch_complete_min=1
2092 iodepth_batch_complete_max=<iodepth>
2093
2094 which means that we will retrieve at least 1 I/O and up to the whole
2095 submitted queue depth. If none of I/O has been completed yet, we will wait.
2096
2097 Example #2::
2098
2099 iodepth_batch_complete_min=0
2100 iodepth_batch_complete_max=<iodepth>
2101
2102 which means that we can retrieve up to the whole submitted queue depth, but
2103 if none of I/O has been completed yet, we will NOT wait and immediately exit
2104 the system call. In this example we simply do polling.
2105
2106.. option:: iodepth_low=int
2107
2108 The low water mark indicating when to start filling the queue
2109 again. Defaults to the same as :option:`iodepth`, meaning that fio will
2110 attempt to keep the queue full at all times. If :option:`iodepth` is set to
c60ebc45 2111 e.g. 16 and *iodepth_low* is set to 4, then after fio has filled the queue of
f80dba8d
MT
2112 16 requests, it will let the depth drain down to 4 before starting to fill
2113 it again.
2114
997b5680
SW
2115.. option:: serialize_overlap=bool
2116
2117 Serialize in-flight I/Os that might otherwise cause or suffer from data races.
2118 When two or more I/Os are submitted simultaneously, there is no guarantee that
2119 the I/Os will be processed or completed in the submitted order. Further, if
2120 two or more of those I/Os are writes, any overlapping region between them can
2121 become indeterminate/undefined on certain storage. These issues can cause
2122 verification to fail erratically when at least one of the racing I/Os is
2123 changing data and the overlapping region has a non-zero size. Setting
2124 ``serialize_overlap`` tells fio to avoid provoking this behavior by explicitly
2125 serializing in-flight I/Os that have a non-zero overlap. Note that setting
ee21ebee 2126 this option can reduce both performance and the :option:`iodepth` achieved.
997b5680
SW
2127 Additionally this option does not work when :option:`io_submit_mode` is set to
2128 offload. Default: false.
2129
f80dba8d
MT
2130.. option:: io_submit_mode=str
2131
2132 This option controls how fio submits the I/O to the I/O engine. The default
2133 is `inline`, which means that the fio job threads submit and reap I/O
2134 directly. If set to `offload`, the job threads will offload I/O submission
2135 to a dedicated pool of I/O threads. This requires some coordination and thus
2136 has a bit of extra overhead, especially for lower queue depth I/O where it
2137 can increase latencies. The benefit is that fio can manage submission rates
2138 independently of the device completion rates. This avoids skewed latency
730bd7d9 2139 reporting if I/O gets backed up on the device side (the coordinated omission
f80dba8d
MT
2140 problem).
2141
2142
2143I/O rate
2144~~~~~~~~
2145
a881438b 2146.. option:: thinktime=time
f80dba8d 2147
f75ede1d
SW
2148 Stall the job for the specified period of time after an I/O has completed before issuing the
2149 next. May be used to simulate processing being done by an application.
947e0fe0 2150 When the unit is omitted, the value is interpreted in microseconds. See
f80dba8d
MT
2151 :option:`thinktime_blocks` and :option:`thinktime_spin`.
2152
a881438b 2153.. option:: thinktime_spin=time
f80dba8d
MT
2154
2155 Only valid if :option:`thinktime` is set - pretend to spend CPU time doing
2156 something with the data received, before falling back to sleeping for the
f75ede1d 2157 rest of the period specified by :option:`thinktime`. When the unit is
947e0fe0 2158 omitted, the value is interpreted in microseconds.
f80dba8d
MT
2159
2160.. option:: thinktime_blocks=int
2161
2162 Only valid if :option:`thinktime` is set - control how many blocks to issue,
f50fbdda
TK
2163 before waiting :option:`thinktime` usecs. If not set, defaults to 1 which will make
2164 fio wait :option:`thinktime` usecs after every block. This effectively makes any
f80dba8d 2165 queue depth setting redundant, since no more than 1 I/O will be queued
f50fbdda 2166 before we have to complete it and do our :option:`thinktime`. In other words, this
f80dba8d 2167 setting effectively caps the queue depth if the latter is larger.
71bfa161 2168
f80dba8d 2169.. option:: rate=int[,int][,int]
71bfa161 2170
f80dba8d
MT
2171 Cap the bandwidth used by this job. The number is in bytes/sec, the normal
2172 suffix rules apply. Comma-separated values may be specified for reads,
2173 writes, and trims as described in :option:`blocksize`.
71bfa161 2174
b25b3464
SW
2175 For example, using `rate=1m,500k` would limit reads to 1MiB/sec and writes to
2176 500KiB/sec. Capping only reads or writes can be done with `rate=,500k` or
2177 `rate=500k,` where the former will only limit writes (to 500KiB/sec) and the
2178 latter will only limit reads.
2179
f80dba8d 2180.. option:: rate_min=int[,int][,int]
71bfa161 2181
f80dba8d
MT
2182 Tell fio to do whatever it can to maintain at least this bandwidth. Failing
2183 to meet this requirement will cause the job to exit. Comma-separated values
2184 may be specified for reads, writes, and trims as described in
2185 :option:`blocksize`.
71bfa161 2186
f80dba8d 2187.. option:: rate_iops=int[,int][,int]
71bfa161 2188
f80dba8d
MT
2189 Cap the bandwidth to this number of IOPS. Basically the same as
2190 :option:`rate`, just specified independently of bandwidth. If the job is
2191 given a block size range instead of a fixed value, the smallest block size
2192 is used as the metric. Comma-separated values may be specified for reads,
2193 writes, and trims as described in :option:`blocksize`.
71bfa161 2194
f80dba8d 2195.. option:: rate_iops_min=int[,int][,int]
71bfa161 2196
f80dba8d
MT
2197 If fio doesn't meet this rate of I/O, it will cause the job to exit.
2198 Comma-separated values may be specified for reads, writes, and trims as
2199 described in :option:`blocksize`.
71bfa161 2200
f80dba8d 2201.. option:: rate_process=str
66c098b8 2202
f80dba8d
MT
2203 This option controls how fio manages rated I/O submissions. The default is
2204 `linear`, which submits I/O in a linear fashion with fixed delays between
c60ebc45 2205 I/Os that gets adjusted based on I/O completion rates. If this is set to
f80dba8d
MT
2206 `poisson`, fio will submit I/O based on a more real world random request
2207 flow, known as the Poisson process
2208 (https://en.wikipedia.org/wiki/Poisson_point_process). The lambda will be
2209 10^6 / IOPS for the given workload.
71bfa161
JA
2210
2211
f80dba8d
MT
2212I/O latency
2213~~~~~~~~~~~
71bfa161 2214
a881438b 2215.. option:: latency_target=time
71bfa161 2216
f80dba8d 2217 If set, fio will attempt to find the max performance point that the given
f75ede1d 2218 workload will run at while maintaining a latency below this target. When
947e0fe0 2219 the unit is omitted, the value is interpreted in microseconds. See
f75ede1d 2220 :option:`latency_window` and :option:`latency_percentile`.
71bfa161 2221
a881438b 2222.. option:: latency_window=time
71bfa161 2223
f80dba8d 2224 Used with :option:`latency_target` to specify the sample window that the job
f75ede1d 2225 is run at varying queue depths to test the performance. When the unit is
947e0fe0 2226 omitted, the value is interpreted in microseconds.
b4692828 2227
f80dba8d 2228.. option:: latency_percentile=float
71bfa161 2229
c60ebc45 2230 The percentage of I/Os that must fall within the criteria specified by
f80dba8d 2231 :option:`latency_target` and :option:`latency_window`. If not set, this
c60ebc45 2232 defaults to 100.0, meaning that all I/Os must be equal or below to the value
f80dba8d 2233 set by :option:`latency_target`.
71bfa161 2234
a881438b 2235.. option:: max_latency=time
71bfa161 2236
f75ede1d 2237 If set, fio will exit the job with an ETIMEDOUT error if it exceeds this
947e0fe0 2238 maximum latency. When the unit is omitted, the value is interpreted in
f75ede1d 2239 microseconds.
71bfa161 2240
f80dba8d 2241.. option:: rate_cycle=int
71bfa161 2242
f80dba8d 2243 Average bandwidth for :option:`rate` and :option:`rate_min` over this number
a47b697c 2244 of milliseconds. Defaults to 1000.
71bfa161 2245
71bfa161 2246
f80dba8d
MT
2247I/O replay
2248~~~~~~~~~~
71bfa161 2249
f80dba8d 2250.. option:: write_iolog=str
c2b1e753 2251
f80dba8d
MT
2252 Write the issued I/O patterns to the specified file. See
2253 :option:`read_iolog`. Specify a separate file for each job, otherwise the
2254 iologs will be interspersed and the file may be corrupt.
c2b1e753 2255
f80dba8d 2256.. option:: read_iolog=str
71bfa161 2257
22413915 2258 Open an iolog with the specified filename and replay the I/O patterns it
f80dba8d
MT
2259 contains. This can be used to store a workload and replay it sometime
2260 later. The iolog given may also be a blktrace binary file, which allows fio
2261 to replay a workload captured by :command:`blktrace`. See
2262 :manpage:`blktrace(8)` for how to capture such logging data. For blktrace
2263 replay, the file needs to be turned into a blkparse binary data file first
2264 (``blkparse <device> -o /dev/null -d file_for_fio.bin``).
71bfa161 2265
589e88b7 2266.. option:: replay_no_stall=bool
71bfa161 2267
f80dba8d 2268 When replaying I/O with :option:`read_iolog` the default behavior is to
22413915 2269 attempt to respect the timestamps within the log and replay them with the
f80dba8d
MT
2270 appropriate delay between IOPS. By setting this variable fio will not
2271 respect the timestamps and attempt to replay them as fast as possible while
2272 still respecting ordering. The result is the same I/O pattern to a given
2273 device, but different timings.
71bfa161 2274
f80dba8d 2275.. option:: replay_redirect=str
b4692828 2276
f80dba8d
MT
2277 While replaying I/O patterns using :option:`read_iolog` the default behavior
2278 is to replay the IOPS onto the major/minor device that each IOP was recorded
2279 from. This is sometimes undesirable because on a different machine those
2280 major/minor numbers can map to a different device. Changing hardware on the
2281 same system can also result in a different major/minor mapping.
730bd7d9 2282 ``replay_redirect`` causes all I/Os to be replayed onto the single specified
f80dba8d 2283 device regardless of the device it was recorded
9207a0cb 2284 from. i.e. :option:`replay_redirect`\= :file:`/dev/sdc` would cause all I/O
f80dba8d
MT
2285 in the blktrace or iolog to be replayed onto :file:`/dev/sdc`. This means
2286 multiple devices will be replayed onto a single device, if the trace
2287 contains multiple devices. If you want multiple devices to be replayed
2288 concurrently to multiple redirected devices you must blkparse your trace
2289 into separate traces and replay them with independent fio invocations.
2290 Unfortunately this also breaks the strict time ordering between multiple
2291 device accesses.
71bfa161 2292
f80dba8d 2293.. option:: replay_align=int
74929ac2 2294
f80dba8d
MT
2295 Force alignment of I/O offsets and lengths in a trace to this power of 2
2296 value.
3c54bc46 2297
f80dba8d 2298.. option:: replay_scale=int
3c54bc46 2299
f80dba8d 2300 Scale sector offsets down by this factor when replaying traces.
3c54bc46 2301
3c54bc46 2302
f80dba8d
MT
2303Threads, processes and job synchronization
2304~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3c54bc46 2305
f80dba8d 2306.. option:: thread
3c54bc46 2307
730bd7d9
SW
2308 Fio defaults to creating jobs by using fork, however if this option is
2309 given, fio will create jobs by using POSIX Threads' function
2310 :manpage:`pthread_create(3)` to create threads instead.
71bfa161 2311
f80dba8d 2312.. option:: wait_for=str
74929ac2 2313
730bd7d9
SW
2314 If set, the current job won't be started until all workers of the specified
2315 waitee job are done.
74929ac2 2316
f80dba8d
MT
2317 ``wait_for`` operates on the job name basis, so there are a few
2318 limitations. First, the waitee must be defined prior to the waiter job
2319 (meaning no forward references). Second, if a job is being referenced as a
2320 waitee, it must have a unique name (no duplicate waitees).
74929ac2 2321
f80dba8d 2322.. option:: nice=int
892a6ffc 2323
f80dba8d 2324 Run the job with the given nice value. See man :manpage:`nice(2)`.
892a6ffc 2325
f80dba8d
MT
2326 On Windows, values less than -15 set the process class to "High"; -1 through
2327 -15 set "Above Normal"; 1 through 15 "Below Normal"; and above 15 "Idle"
2328 priority class.
74929ac2 2329
f80dba8d 2330.. option:: prio=int
71bfa161 2331
f80dba8d
MT
2332 Set the I/O priority value of this job. Linux limits us to a positive value
2333 between 0 and 7, with 0 being the highest. See man
2334 :manpage:`ionice(1)`. Refer to an appropriate manpage for other operating
2335 systems since meaning of priority may differ.
71bfa161 2336
f80dba8d 2337.. option:: prioclass=int
d59aa780 2338
f80dba8d 2339 Set the I/O priority class. See man :manpage:`ionice(1)`.
d59aa780 2340
f80dba8d 2341.. option:: cpumask=int
71bfa161 2342
22413915
SW
2343 Set the CPU affinity of this job. The parameter given is a bit mask of
2344 allowed CPUs the job may run on. So if you want the allowed CPUs to be 1
f80dba8d
MT
2345 and 5, you would pass the decimal value of (1 << 1 | 1 << 5), or 34. See man
2346 :manpage:`sched_setaffinity(2)`. This may not work on all supported
2347 operating systems or kernel versions. This option doesn't work well for a
2348 higher CPU count than what you can store in an integer mask, so it can only
2349 control cpus 1-32. For boxes with larger CPU counts, use
2350 :option:`cpus_allowed`.
6d500c2e 2351
f80dba8d 2352.. option:: cpus_allowed=str
6d500c2e 2353
730bd7d9
SW
2354 Controls the same options as :option:`cpumask`, but accepts a textual
2355 specification of the permitted CPUs instead. So to use CPUs 1 and 5 you
2356 would specify ``cpus_allowed=1,5``. This option also allows a range of CPUs
2357 to be specified -- say you wanted a binding to CPUs 1, 5, and 8 to 15, you
2358 would set ``cpus_allowed=1,5,8-15``.
6d500c2e 2359
f80dba8d 2360.. option:: cpus_allowed_policy=str
6d500c2e 2361
f80dba8d 2362 Set the policy of how fio distributes the CPUs specified by
730bd7d9 2363 :option:`cpus_allowed` or :option:`cpumask`. Two policies are supported:
6d500c2e 2364
f80dba8d
MT
2365 **shared**
2366 All jobs will share the CPU set specified.
2367 **split**
2368 Each job will get a unique CPU from the CPU set.
6d500c2e 2369
22413915 2370 **shared** is the default behavior, if the option isn't specified. If
f80dba8d
MT
2371 **split** is specified, then fio will will assign one cpu per job. If not
2372 enough CPUs are given for the jobs listed, then fio will roundrobin the CPUs
2373 in the set.
6d500c2e 2374
f80dba8d 2375.. option:: numa_cpu_nodes=str
6d500c2e 2376
f80dba8d
MT
2377 Set this job running on specified NUMA nodes' CPUs. The arguments allow
2378 comma delimited list of cpu numbers, A-B ranges, or `all`. Note, to enable
ac8ca2af 2379 NUMA options support, fio must be built on a system with libnuma-dev(el)
f80dba8d 2380 installed.
61b9861d 2381
f80dba8d 2382.. option:: numa_mem_policy=str
61b9861d 2383
f80dba8d
MT
2384 Set this job's memory policy and corresponding NUMA nodes. Format of the
2385 arguments::
5c94b008 2386
f80dba8d 2387 <mode>[:<nodelist>]
ce35b1ec 2388
730bd7d9
SW
2389 ``mode`` is one of the following memory poicies: ``default``, ``prefer``,
2390 ``bind``, ``interleave`` or ``local``. For ``default`` and ``local`` memory
2391 policies, no node needs to be specified. For ``prefer``, only one node is
2392 allowed. For ``bind`` and ``interleave`` the ``nodelist`` may be as
2393 follows: a comma delimited list of numbers, A-B ranges, or `all`.
71bfa161 2394
f80dba8d 2395.. option:: cgroup=str
390b1537 2396
f80dba8d
MT
2397 Add job to this control group. If it doesn't exist, it will be created. The
2398 system must have a mounted cgroup blkio mount point for this to work. If
2399 your system doesn't have it mounted, you can do so with::
5af1c6f3 2400
f80dba8d 2401 # mount -t cgroup -o blkio none /cgroup
5af1c6f3 2402
f80dba8d 2403.. option:: cgroup_weight=int
5af1c6f3 2404
f80dba8d
MT
2405 Set the weight of the cgroup to this value. See the documentation that comes
2406 with the kernel, allowed values are in the range of 100..1000.
a086c257 2407
f80dba8d 2408.. option:: cgroup_nodelete=bool
8c07860d 2409
f80dba8d
MT
2410 Normally fio will delete the cgroups it has created after the job
2411 completion. To override this behavior and to leave cgroups around after the
2412 job completion, set ``cgroup_nodelete=1``. This can be useful if one wants
2413 to inspect various cgroup files after job completion. Default: false.
8c07860d 2414
f80dba8d 2415.. option:: flow_id=int
8c07860d 2416
f80dba8d
MT
2417 The ID of the flow. If not specified, it defaults to being a global
2418 flow. See :option:`flow`.
1907dbc6 2419
f80dba8d 2420.. option:: flow=int
71bfa161 2421
f80dba8d
MT
2422 Weight in token-based flow control. If this value is used, then there is a
2423 'flow counter' which is used to regulate the proportion of activity between
2424 two or more jobs. Fio attempts to keep this flow counter near zero. The
2425 ``flow`` parameter stands for how much should be added or subtracted to the
2426 flow counter on each iteration of the main I/O loop. That is, if one job has
2427 ``flow=8`` and another job has ``flow=-1``, then there will be a roughly 1:8
2428 ratio in how much one runs vs the other.
71bfa161 2429
f80dba8d 2430.. option:: flow_watermark=int
a31041ea 2431
f80dba8d
MT
2432 The maximum value that the absolute value of the flow counter is allowed to
2433 reach before the job must wait for a lower value of the counter.
82407585 2434
f80dba8d 2435.. option:: flow_sleep=int
82407585 2436
f80dba8d
MT
2437 The period of time, in microseconds, to wait after the flow watermark has
2438 been exceeded before retrying operations.
82407585 2439
f80dba8d 2440.. option:: stonewall, wait_for_previous
82407585 2441
f80dba8d
MT
2442 Wait for preceding jobs in the job file to exit, before starting this
2443 one. Can be used to insert serialization points in the job file. A stone
2444 wall also implies starting a new reporting group, see
2445 :option:`group_reporting`.
2446
2447.. option:: exitall
2448
730bd7d9
SW
2449 By default, fio will continue running all other jobs when one job finishes
2450 but sometimes this is not the desired action. Setting ``exitall`` will
2451 instead make fio terminate all other jobs when one job finishes.
f80dba8d
MT
2452
2453.. option:: exec_prerun=str
2454
2455 Before running this job, issue the command specified through
2456 :manpage:`system(3)`. Output is redirected in a file called
2457 :file:`jobname.prerun.txt`.
2458
2459.. option:: exec_postrun=str
2460
2461 After the job completes, issue the command specified though
2462 :manpage:`system(3)`. Output is redirected in a file called
2463 :file:`jobname.postrun.txt`.
2464
2465.. option:: uid=int
2466
2467 Instead of running as the invoking user, set the user ID to this value
2468 before the thread/process does any work.
2469
2470.. option:: gid=int
2471
2472 Set group ID, see :option:`uid`.
2473
2474
2475Verification
2476~~~~~~~~~~~~
2477
2478.. option:: verify_only
2479
2480 Do not perform specified workload, only verify data still matches previous
2481 invocation of this workload. This option allows one to check data multiple
2482 times at a later date without overwriting it. This option makes sense only
2483 for workloads that write data, and does not support workloads with the
2484 :option:`time_based` option set.
2485
2486.. option:: do_verify=bool
2487
2488 Run the verify phase after a write phase. Only valid if :option:`verify` is
2489 set. Default: true.
2490
2491.. option:: verify=str
2492
2493 If writing to a file, fio can verify the file contents after each iteration
2494 of the job. Each verification method also implies verification of special
2495 header, which is written to the beginning of each block. This header also
2496 includes meta information, like offset of the block, block number, timestamp
2497 when block was written, etc. :option:`verify` can be combined with
2498 :option:`verify_pattern` option. The allowed values are:
2499
2500 **md5**
2501 Use an md5 sum of the data area and store it in the header of
2502 each block.
2503
2504 **crc64**
2505 Use an experimental crc64 sum of the data area and store it in the
2506 header of each block.
2507
2508 **crc32c**
a5896300
SW
2509 Use a crc32c sum of the data area and store it in the header of
2510 each block. This will automatically use hardware acceleration
2511 (e.g. SSE4.2 on an x86 or CRC crypto extensions on ARM64) but will
2512 fall back to software crc32c if none is found. Generally the
2513 fatest checksum fio supports when hardware accelerated.
f80dba8d
MT
2514
2515 **crc32c-intel**
a5896300 2516 Synonym for crc32c.
f80dba8d
MT
2517
2518 **crc32**
2519 Use a crc32 sum of the data area and store it in the header of each
2520 block.
2521
2522 **crc16**
2523 Use a crc16 sum of the data area and store it in the header of each
2524 block.
2525
2526 **crc7**
2527 Use a crc7 sum of the data area and store it in the header of each
2528 block.
2529
2530 **xxhash**
2531 Use xxhash as the checksum function. Generally the fastest software
2532 checksum that fio supports.
2533
2534 **sha512**
2535 Use sha512 as the checksum function.
2536
2537 **sha256**
2538 Use sha256 as the checksum function.
2539
2540 **sha1**
2541 Use optimized sha1 as the checksum function.
82407585 2542
ae3a5acc
JA
2543 **sha3-224**
2544 Use optimized sha3-224 as the checksum function.
2545
2546 **sha3-256**
2547 Use optimized sha3-256 as the checksum function.
2548
2549 **sha3-384**
2550 Use optimized sha3-384 as the checksum function.
2551
2552 **sha3-512**
2553 Use optimized sha3-512 as the checksum function.
2554
f80dba8d
MT
2555 **meta**
2556 This option is deprecated, since now meta information is included in
2557 generic verification header and meta verification happens by
2558 default. For detailed information see the description of the
2559 :option:`verify` setting. This option is kept because of
2560 compatibility's sake with old configurations. Do not use it.
2561
2562 **pattern**
2563 Verify a strict pattern. Normally fio includes a header with some
2564 basic information and checksumming, but if this option is set, only
2565 the specific pattern set with :option:`verify_pattern` is verified.
2566
2567 **null**
2568 Only pretend to verify. Useful for testing internals with
9207a0cb 2569 :option:`ioengine`\=null, not for much else.
f80dba8d
MT
2570
2571 This option can be used for repeated burn-in tests of a system to make sure
2572 that the written data is also correctly read back. If the data direction
2573 given is a read or random read, fio will assume that it should verify a
2574 previously written file. If the data direction includes any form of write,
2575 the verify will be of the newly written data.
2576
2577.. option:: verifysort=bool
2578
2579 If true, fio will sort written verify blocks when it deems it faster to read
2580 them back in a sorted manner. This is often the case when overwriting an
2581 existing file, since the blocks are already laid out in the file system. You
2582 can ignore this option unless doing huge amounts of really fast I/O where
2583 the red-black tree sorting CPU time becomes significant. Default: true.
2584
2585.. option:: verifysort_nr=int
2586
2b455dbf 2587 Pre-load and sort verify blocks for a read workload.
f80dba8d
MT
2588
2589.. option:: verify_offset=int
2590
2591 Swap the verification header with data somewhere else in the block before
2592 writing. It is swapped back before verifying.
2593
2594.. option:: verify_interval=int
2595
2596 Write the verification header at a finer granularity than the
2597 :option:`blocksize`. It will be written for chunks the size of
2598 ``verify_interval``. :option:`blocksize` should divide this evenly.
2599
2600.. option:: verify_pattern=str
2601
2602 If set, fio will fill the I/O buffers with this pattern. Fio defaults to
2603 filling with totally random bytes, but sometimes it's interesting to fill
2604 with a known pattern for I/O verification purposes. Depending on the width
730bd7d9 2605 of the pattern, fio will fill 1/2/3/4 bytes of the buffer at the time (it can
f80dba8d
MT
2606 be either a decimal or a hex number). The ``verify_pattern`` if larger than
2607 a 32-bit quantity has to be a hex number that starts with either "0x" or
2608 "0X". Use with :option:`verify`. Also, ``verify_pattern`` supports %o
2609 format, which means that for each block offset will be written and then
2610 verified back, e.g.::
61b9861d
RP
2611
2612 verify_pattern=%o
2613
f80dba8d
MT
2614 Or use combination of everything::
2615
61b9861d 2616 verify_pattern=0xff%o"abcd"-12
e28218f3 2617
f80dba8d
MT
2618.. option:: verify_fatal=bool
2619
2620 Normally fio will keep checking the entire contents before quitting on a
2621 block verification failure. If this option is set, fio will exit the job on
2622 the first observed failure. Default: false.
2623
2624.. option:: verify_dump=bool
2625
2626 If set, dump the contents of both the original data block and the data block
2627 we read off disk to files. This allows later analysis to inspect just what
2628 kind of data corruption occurred. Off by default.
2629
2630.. option:: verify_async=int
2631
2632 Fio will normally verify I/O inline from the submitting thread. This option
2633 takes an integer describing how many async offload threads to create for I/O
2634 verification instead, causing fio to offload the duty of verifying I/O
2635 contents to one or more separate threads. If using this offload option, even
2636 sync I/O engines can benefit from using an :option:`iodepth` setting higher
2637 than 1, as it allows them to have I/O in flight while verifies are running.
d7e6ea1c 2638 Defaults to 0 async threads, i.e. verification is not asynchronous.
f80dba8d
MT
2639
2640.. option:: verify_async_cpus=str
2641
2642 Tell fio to set the given CPU affinity on the async I/O verification
2643 threads. See :option:`cpus_allowed` for the format used.
2644
2645.. option:: verify_backlog=int
2646
2647 Fio will normally verify the written contents of a job that utilizes verify
2648 once that job has completed. In other words, everything is written then
2649 everything is read back and verified. You may want to verify continually
2650 instead for a variety of reasons. Fio stores the meta data associated with
2651 an I/O block in memory, so for large verify workloads, quite a bit of memory
2652 would be used up holding this meta data. If this option is enabled, fio will
2653 write only N blocks before verifying these blocks.
2654
2655.. option:: verify_backlog_batch=int
2656
2657 Control how many blocks fio will verify if :option:`verify_backlog` is
2658 set. If not set, will default to the value of :option:`verify_backlog`
2659 (meaning the entire queue is read back and verified). If
2660 ``verify_backlog_batch`` is less than :option:`verify_backlog` then not all
2661 blocks will be verified, if ``verify_backlog_batch`` is larger than
2662 :option:`verify_backlog`, some blocks will be verified more than once.
2663
2664.. option:: verify_state_save=bool
2665
2666 When a job exits during the write phase of a verify workload, save its
2667 current state. This allows fio to replay up until that point, if the verify
2668 state is loaded for the verify read phase. The format of the filename is,
2669 roughly::
2670
f50fbdda 2671 <type>-<jobname>-<jobindex>-verify.state.
f80dba8d
MT
2672
2673 <type> is "local" for a local run, "sock" for a client/server socket
2674 connection, and "ip" (192.168.0.1, for instance) for a networked
d7e6ea1c 2675 client/server connection. Defaults to true.
f80dba8d
MT
2676
2677.. option:: verify_state_load=bool
2678
2679 If a verify termination trigger was used, fio stores the current write state
2680 of each thread. This can be used at verification time so that fio knows how
2681 far it should verify. Without this information, fio will run a full
a47b697c
SW
2682 verification pass, according to the settings in the job file used. Default
2683 false.
f80dba8d
MT
2684
2685.. option:: trim_percentage=int
2686
2687 Number of verify blocks to discard/trim.
2688
2689.. option:: trim_verify_zero=bool
2690
22413915 2691 Verify that trim/discarded blocks are returned as zeros.
f80dba8d
MT
2692
2693.. option:: trim_backlog=int
2694
5cfd1e9a 2695 Trim after this number of blocks are written.
f80dba8d
MT
2696
2697.. option:: trim_backlog_batch=int
2698
2699 Trim this number of I/O blocks.
2700
2701.. option:: experimental_verify=bool
2702
2703 Enable experimental verification.
2704
f80dba8d
MT
2705Steady state
2706~~~~~~~~~~~~
2707
2708.. option:: steadystate=str:float, ss=str:float
2709
2710 Define the criterion and limit for assessing steady state performance. The
2711 first parameter designates the criterion whereas the second parameter sets
2712 the threshold. When the criterion falls below the threshold for the
2713 specified duration, the job will stop. For example, `iops_slope:0.1%` will
2714 direct fio to terminate the job when the least squares regression slope
2715 falls below 0.1% of the mean IOPS. If :option:`group_reporting` is enabled
2716 this will apply to all jobs in the group. Below is the list of available
2717 steady state assessment criteria. All assessments are carried out using only
2718 data from the rolling collection window. Threshold limits can be expressed
2719 as a fixed value or as a percentage of the mean in the collection window.
2720
2721 **iops**
2722 Collect IOPS data. Stop the job if all individual IOPS measurements
2723 are within the specified limit of the mean IOPS (e.g., ``iops:2``
2724 means that all individual IOPS values must be within 2 of the mean,
2725 whereas ``iops:0.2%`` means that all individual IOPS values must be
2726 within 0.2% of the mean IOPS to terminate the job).
2727
2728 **iops_slope**
2729 Collect IOPS data and calculate the least squares regression
2730 slope. Stop the job if the slope falls below the specified limit.
2731
2732 **bw**
2733 Collect bandwidth data. Stop the job if all individual bandwidth
2734 measurements are within the specified limit of the mean bandwidth.
2735
2736 **bw_slope**
2737 Collect bandwidth data and calculate the least squares regression
2738 slope. Stop the job if the slope falls below the specified limit.
2739
2740.. option:: steadystate_duration=time, ss_dur=time
2741
2742 A rolling window of this duration will be used to judge whether steady state
2743 has been reached. Data will be collected once per second. The default is 0
f75ede1d 2744 which disables steady state detection. When the unit is omitted, the
947e0fe0 2745 value is interpreted in seconds.
f80dba8d
MT
2746
2747.. option:: steadystate_ramp_time=time, ss_ramp=time
2748
2749 Allow the job to run for the specified duration before beginning data
2750 collection for checking the steady state job termination criterion. The
947e0fe0 2751 default is 0. When the unit is omitted, the value is interpreted in seconds.
f80dba8d
MT
2752
2753
2754Measurements and reporting
2755~~~~~~~~~~~~~~~~~~~~~~~~~~
2756
2757.. option:: per_job_logs=bool
2758
2759 If set, this generates bw/clat/iops log with per file private filenames. If
2760 not set, jobs with identical names will share the log filename. Default:
2761 true.
2762
2763.. option:: group_reporting
2764
2765 It may sometimes be interesting to display statistics for groups of jobs as
2766 a whole instead of for each individual job. This is especially true if
2767 :option:`numjobs` is used; looking at individual thread/process output
2768 quickly becomes unwieldy. To see the final report per-group instead of
2769 per-job, use :option:`group_reporting`. Jobs in a file will be part of the
2770 same reporting group, unless if separated by a :option:`stonewall`, or by
2771 using :option:`new_group`.
2772
2773.. option:: new_group
2774
2775 Start a new reporting group. See: :option:`group_reporting`. If not given,
2776 all jobs in a file will be part of the same reporting group, unless
2777 separated by a :option:`stonewall`.
2778
589e88b7 2779.. option:: stats=bool
8243be59
JA
2780
2781 By default, fio collects and shows final output results for all jobs
2782 that run. If this option is set to 0, then fio will ignore it in
2783 the final stat output.
2784
f80dba8d
MT
2785.. option:: write_bw_log=str
2786
2787 If given, write a bandwidth log for this job. Can be used to store data of
074f0817 2788 the bandwidth of the jobs in their lifetime.
f80dba8d 2789
074f0817
SW
2790 If no str argument is given, the default filename of
2791 :file:`jobname_type.x.log` is used. Even when the argument is given, fio
2792 will still append the type of log. So if one specifies::
2793
2794 write_bw_log=foo
f80dba8d 2795
074f0817
SW
2796 The actual log name will be :file:`foo_bw.x.log` where `x` is the index
2797 of the job (`1..N`, where `N` is the number of jobs). If
2798 :option:`per_job_logs` is false, then the filename will not include the
2799 `.x` job index.
e3cedca7 2800
074f0817
SW
2801 The included :command:`fio_generate_plots` script uses :command:`gnuplot` to turn these
2802 text files into nice graphs. See `Log File Formats`_ for how data is
2803 structured within the file.
2804
2805.. option:: write_lat_log=str
e3cedca7 2806
074f0817 2807 Same as :option:`write_bw_log`, except this option creates I/O
77b7e675
SW
2808 submission (e.g., :file:`name_slat.x.log`), completion (e.g.,
2809 :file:`name_clat.x.log`), and total (e.g., :file:`name_lat.x.log`)
074f0817
SW
2810 latency files instead. See :option:`write_bw_log` for details about
2811 the filename format and `Log File Formats`_ for how data is structured
2812 within the files.
be4ecfdf 2813
f80dba8d 2814.. option:: write_hist_log=str
06842027 2815
074f0817 2816 Same as :option:`write_bw_log` but writes an I/O completion latency
77b7e675 2817 histogram file (e.g., :file:`name_hist.x.log`) instead. Note that this
074f0817
SW
2818 file will be empty unless :option:`log_hist_msec` has also been set.
2819 See :option:`write_bw_log` for details about the filename format and
2820 `Log File Formats`_ for how data is structured within the file.
06842027 2821
f80dba8d 2822.. option:: write_iops_log=str
06842027 2823
074f0817 2824 Same as :option:`write_bw_log`, but writes an IOPS file (e.g.
77b7e675 2825 :file:`name_iops.x.log`) instead. See :option:`write_bw_log` for
074f0817
SW
2826 details about the filename format and `Log File Formats`_ for how data
2827 is structured within the file.
06842027 2828
f80dba8d 2829.. option:: log_avg_msec=int
06842027 2830
f80dba8d
MT
2831 By default, fio will log an entry in the iops, latency, or bw log for every
2832 I/O that completes. When writing to the disk log, that can quickly grow to a
2833 very large size. Setting this option makes fio average the each log entry
2834 over the specified period of time, reducing the resolution of the log. See
2835 :option:`log_max_value` as well. Defaults to 0, logging all entries.
6fc82095 2836 Also see `Log File Formats`_.
06842027 2837
f80dba8d 2838.. option:: log_hist_msec=int
06842027 2839
f80dba8d
MT
2840 Same as :option:`log_avg_msec`, but logs entries for completion latency
2841 histograms. Computing latency percentiles from averages of intervals using
c60ebc45 2842 :option:`log_avg_msec` is inaccurate. Setting this option makes fio log
f80dba8d
MT
2843 histogram entries over the specified period of time, reducing log sizes for
2844 high IOPS devices while retaining percentile accuracy. See
074f0817
SW
2845 :option:`log_hist_coarseness` and :option:`write_hist_log` as well.
2846 Defaults to 0, meaning histogram logging is disabled.
06842027 2847
f80dba8d 2848.. option:: log_hist_coarseness=int
06842027 2849
f80dba8d
MT
2850 Integer ranging from 0 to 6, defining the coarseness of the resolution of
2851 the histogram logs enabled with :option:`log_hist_msec`. For each increment
2852 in coarseness, fio outputs half as many bins. Defaults to 0, for which
074f0817
SW
2853 histogram logs contain 1216 latency bins. See :option:`write_hist_log`
2854 and `Log File Formats`_.
8b28bd41 2855
f80dba8d 2856.. option:: log_max_value=bool
66c098b8 2857
f80dba8d
MT
2858 If :option:`log_avg_msec` is set, fio logs the average over that window. If
2859 you instead want to log the maximum value, set this option to 1. Defaults to
2860 0, meaning that averaged values are logged.
a696fa2a 2861
589e88b7 2862.. option:: log_offset=bool
a696fa2a 2863
f80dba8d 2864 If this is set, the iolog options will include the byte offset for the I/O
5a83478f
SW
2865 entry as well as the other data values. Defaults to 0 meaning that
2866 offsets are not present in logs. Also see `Log File Formats`_.
71bfa161 2867
f80dba8d 2868.. option:: log_compression=int
7de87099 2869
f80dba8d
MT
2870 If this is set, fio will compress the I/O logs as it goes, to keep the
2871 memory footprint lower. When a log reaches the specified size, that chunk is
2872 removed and compressed in the background. Given that I/O logs are fairly
2873 highly compressible, this yields a nice memory savings for longer runs. The
2874 downside is that the compression will consume some background CPU cycles, so
2875 it may impact the run. This, however, is also true if the logging ends up
2876 consuming most of the system memory. So pick your poison. The I/O logs are
2877 saved normally at the end of a run, by decompressing the chunks and storing
2878 them in the specified log file. This feature depends on the availability of
2879 zlib.
e0b0d892 2880
f80dba8d 2881.. option:: log_compression_cpus=str
e0b0d892 2882
f80dba8d
MT
2883 Define the set of CPUs that are allowed to handle online log compression for
2884 the I/O jobs. This can provide better isolation between performance
2885 sensitive jobs, and background compression work.
9e684a49 2886
f80dba8d 2887.. option:: log_store_compressed=bool
9e684a49 2888
f80dba8d
MT
2889 If set, fio will store the log files in a compressed format. They can be
2890 decompressed with fio, using the :option:`--inflate-log` command line
2891 parameter. The files will be stored with a :file:`.fz` suffix.
9e684a49 2892
f80dba8d 2893.. option:: log_unix_epoch=bool
9e684a49 2894
f80dba8d
MT
2895 If set, fio will log Unix timestamps to the log files produced by enabling
2896 write_type_log for each log type, instead of the default zero-based
2897 timestamps.
2898
2899.. option:: block_error_percentiles=bool
2900
2901 If set, record errors in trim block-sized units from writes and trims and
2902 output a histogram of how many trims it took to get to errors, and what kind
2903 of error was encountered.
2904
2905.. option:: bwavgtime=int
2906
2907 Average the calculated bandwidth over the given time. Value is specified in
2908 milliseconds. If the job also does bandwidth logging through
2909 :option:`write_bw_log`, then the minimum of this option and
2910 :option:`log_avg_msec` will be used. Default: 500ms.
2911
2912.. option:: iopsavgtime=int
2913
2914 Average the calculated IOPS over the given time. Value is specified in
2915 milliseconds. If the job also does IOPS logging through
2916 :option:`write_iops_log`, then the minimum of this option and
2917 :option:`log_avg_msec` will be used. Default: 500ms.
2918
2919.. option:: disk_util=bool
2920
2921 Generate disk utilization statistics, if the platform supports it.
2922 Default: true.
2923
2924.. option:: disable_lat=bool
2925
2926 Disable measurements of total latency numbers. Useful only for cutting back
2927 the number of calls to :manpage:`gettimeofday(2)`, as that does impact
2928 performance at really high IOPS rates. Note that to really get rid of a
2929 large amount of these calls, this option must be used with
f75ede1d 2930 :option:`disable_slat` and :option:`disable_bw_measurement` as well.
f80dba8d
MT
2931
2932.. option:: disable_clat=bool
2933
2934 Disable measurements of completion latency numbers. See
2935 :option:`disable_lat`.
2936
2937.. option:: disable_slat=bool
2938
2939 Disable measurements of submission latency numbers. See
f50fbdda 2940 :option:`disable_lat`.
f80dba8d 2941
f75ede1d 2942.. option:: disable_bw_measurement=bool, disable_bw=bool
f80dba8d
MT
2943
2944 Disable measurements of throughput/bandwidth numbers. See
2945 :option:`disable_lat`.
2946
2947.. option:: clat_percentiles=bool
2948
b599759b
JA
2949 Enable the reporting of percentiles of completion latencies. This
2950 option is mutually exclusive with :option:`lat_percentiles`.
2951
2952.. option:: lat_percentiles=bool
2953
b71968b1 2954 Enable the reporting of percentiles of I/O latencies. This is similar
b599759b
JA
2955 to :option:`clat_percentiles`, except that this includes the
2956 submission latency. This option is mutually exclusive with
2957 :option:`clat_percentiles`.
f80dba8d
MT
2958
2959.. option:: percentile_list=float_list
2960
c32ba107
JA
2961 Overwrite the default list of percentiles for completion latencies and
2962 the block error histogram. Each number is a floating number in the
2963 range (0,100], and the maximum length of the list is 20. Use ``:`` to
2964 separate the numbers, and list the numbers in ascending order. For
2965 example, ``--percentile_list=99.5:99.9`` will cause fio to report the
2966 values of completion latency below which 99.5% and 99.9% of the observed
2967 latencies fell, respectively.
f80dba8d 2968
e883cb35
JF
2969.. option:: significant_figures=int
2970
c32ba107
JA
2971 If using :option:`--output-format` of `normal`, set the significant
2972 figures to this value. Higher values will yield more precise IOPS and
2973 throughput units, while lower values will round. Requires a minimum
2974 value of 1 and a maximum value of 10. Defaults to 4.
e883cb35 2975
f80dba8d
MT
2976
2977Error handling
2978~~~~~~~~~~~~~~
2979
2980.. option:: exitall_on_error
2981
2982 When one job finishes in error, terminate the rest. The default is to wait
2983 for each job to finish.
2984
2985.. option:: continue_on_error=str
2986
2987 Normally fio will exit the job on the first observed failure. If this option
2988 is set, fio will continue the job when there is a 'non-fatal error' (EIO or
2989 EILSEQ) until the runtime is exceeded or the I/O size specified is
2990 completed. If this option is used, there are two more stats that are
2991 appended, the total error count and the first error. The error field given
2992 in the stats is the first error that was hit during the run.
2993
2994 The allowed values are:
2995
2996 **none**
2997 Exit on any I/O or verify errors.
2998
2999 **read**
3000 Continue on read errors, exit on all others.
3001
3002 **write**
3003 Continue on write errors, exit on all others.
3004
3005 **io**
3006 Continue on any I/O error, exit on all others.
3007
3008 **verify**
3009 Continue on verify errors, exit on all others.
3010
3011 **all**
3012 Continue on all errors.
3013
3014 **0**
3015 Backward-compatible alias for 'none'.
3016
3017 **1**
3018 Backward-compatible alias for 'all'.
3019
3020.. option:: ignore_error=str
3021
3022 Sometimes you want to ignore some errors during test in that case you can
a35ef7cb
TK
3023 specify error list for each error type, instead of only being able to
3024 ignore the default 'non-fatal error' using :option:`continue_on_error`.
f80dba8d
MT
3025 ``ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST`` errors for
3026 given error type is separated with ':'. Error may be symbol ('ENOSPC',
3027 'ENOMEM') or integer. Example::
3028
3029 ignore_error=EAGAIN,ENOSPC:122
3030
3031 This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from
a35ef7cb
TK
3032 WRITE. This option works by overriding :option:`continue_on_error` with
3033 the list of errors for each error type if any.
f80dba8d
MT
3034
3035.. option:: error_dump=bool
3036
3037 If set dump every error even if it is non fatal, true by default. If
3038 disabled only fatal error will be dumped.
3039
f75ede1d
SW
3040Running predefined workloads
3041----------------------------
3042
3043Fio includes predefined profiles that mimic the I/O workloads generated by
3044other tools.
3045
3046.. option:: profile=str
3047
3048 The predefined workload to run. Current profiles are:
3049
3050 **tiobench**
3051 Threaded I/O bench (tiotest/tiobench) like workload.
3052
3053 **act**
3054 Aerospike Certification Tool (ACT) like workload.
3055
3056To view a profile's additional options use :option:`--cmdhelp` after specifying
3057the profile. For example::
3058
f50fbdda 3059 $ fio --profile=act --cmdhelp
f75ede1d
SW
3060
3061Act profile options
3062~~~~~~~~~~~~~~~~~~~
3063
3064.. option:: device-names=str
3065 :noindex:
3066
3067 Devices to use.
3068
3069.. option:: load=int
3070 :noindex:
3071
3072 ACT load multiplier. Default: 1.
3073
3074.. option:: test-duration=time
3075 :noindex:
3076
947e0fe0
SW
3077 How long the entire test takes to run. When the unit is omitted, the value
3078 is given in seconds. Default: 24h.
f75ede1d
SW
3079
3080.. option:: threads-per-queue=int
3081 :noindex:
3082
f50fbdda 3083 Number of read I/O threads per device. Default: 8.
f75ede1d
SW
3084
3085.. option:: read-req-num-512-blocks=int
3086 :noindex:
3087
3088 Number of 512B blocks to read at the time. Default: 3.
3089
3090.. option:: large-block-op-kbytes=int
3091 :noindex:
3092
3093 Size of large block ops in KiB (writes). Default: 131072.
3094
3095.. option:: prep
3096 :noindex:
3097
3098 Set to run ACT prep phase.
3099
3100Tiobench profile options
3101~~~~~~~~~~~~~~~~~~~~~~~~
3102
3103.. option:: size=str
3104 :noindex:
3105
f50fbdda 3106 Size in MiB.
f75ede1d
SW
3107
3108.. option:: block=int
3109 :noindex:
3110
3111 Block size in bytes. Default: 4096.
3112
3113.. option:: numruns=int
3114 :noindex:
3115
3116 Number of runs.
3117
3118.. option:: dir=str
3119 :noindex:
3120
3121 Test directory.
3122
3123.. option:: threads=int
3124 :noindex:
3125
3126 Number of threads.
f80dba8d
MT
3127
3128Interpreting the output
3129-----------------------
3130
36214730
SW
3131..
3132 Example output was based on the following:
3133 TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --time_based \
3134 --rate=1256k --bs=14K --name=quick --runtime=1s --name=mixed \
3135 --runtime=2m --rw=rw
3136
f80dba8d
MT
3137Fio spits out a lot of output. While running, fio will display the status of the
3138jobs created. An example of that would be::
3139
9d25d068 3140 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]
f80dba8d 3141
36214730
SW
3142The characters inside the first set of square brackets denote the current status of
3143each thread. The first character is the first job defined in the job file, and so
3144forth. The possible values (in typical life cycle order) are:
f80dba8d
MT
3145
3146+------+-----+-----------------------------------------------------------+
3147| Idle | Run | |
3148+======+=====+===========================================================+
3149| P | | Thread setup, but not started. |
3150+------+-----+-----------------------------------------------------------+
3151| C | | Thread created. |
3152+------+-----+-----------------------------------------------------------+
3153| I | | Thread initialized, waiting or generating necessary data. |
3154+------+-----+-----------------------------------------------------------+
3155| | p | Thread running pre-reading file(s). |
3156+------+-----+-----------------------------------------------------------+
36214730
SW
3157| | / | Thread is in ramp period. |
3158+------+-----+-----------------------------------------------------------+
f80dba8d
MT
3159| | R | Running, doing sequential reads. |
3160+------+-----+-----------------------------------------------------------+
3161| | r | Running, doing random reads. |
3162+------+-----+-----------------------------------------------------------+
3163| | W | Running, doing sequential writes. |
3164+------+-----+-----------------------------------------------------------+
3165| | w | Running, doing random writes. |
3166+------+-----+-----------------------------------------------------------+
3167| | M | Running, doing mixed sequential reads/writes. |
3168+------+-----+-----------------------------------------------------------+
3169| | m | Running, doing mixed random reads/writes. |
3170+------+-----+-----------------------------------------------------------+
36214730
SW
3171| | D | Running, doing sequential trims. |
3172+------+-----+-----------------------------------------------------------+
3173| | d | Running, doing random trims. |
3174+------+-----+-----------------------------------------------------------+
3175| | F | Running, currently waiting for :manpage:`fsync(2)`. |
f80dba8d
MT
3176+------+-----+-----------------------------------------------------------+
3177| | V | Running, doing verification of written data. |
3178+------+-----+-----------------------------------------------------------+
36214730
SW
3179| f | | Thread finishing. |
3180+------+-----+-----------------------------------------------------------+
f80dba8d
MT
3181| E | | Thread exited, not reaped by main thread yet. |
3182+------+-----+-----------------------------------------------------------+
36214730 3183| _ | | Thread reaped. |
f80dba8d
MT
3184+------+-----+-----------------------------------------------------------+
3185| X | | Thread reaped, exited with an error. |
3186+------+-----+-----------------------------------------------------------+
3187| K | | Thread reaped, exited due to signal. |
3188+------+-----+-----------------------------------------------------------+
3189
36214730
SW
3190..
3191 Example output was based on the following:
3192 TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --runtime=58m \
3193 --time_based --rate=2512k --bs=256K --numjobs=10 \
3194 --name=readers --rw=read --name=writers --rw=write
3195
f80dba8d 3196Fio will condense the thread string as not to take up more space on the command
36214730 3197line than needed. For instance, if you have 10 readers and 10 writers running,
f80dba8d
MT
3198the output would look like this::
3199
9d25d068 3200 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]
f80dba8d 3201
36214730
SW
3202Note that the status string is displayed in order, so it's possible to tell which of
3203the jobs are currently doing what. In the example above this means that jobs 1--10
3204are readers and 11--20 are writers.
f80dba8d
MT
3205
3206The other values are fairly self explanatory -- number of threads currently
36214730
SW
3207running and doing I/O, the number of currently open files (f=), the estimated
3208completion percentage, the rate of I/O since last check (read speed listed first,
f50fbdda
TK
3209then write speed and optionally trim speed) in terms of bandwidth and IOPS,
3210and time to completion for the current running group. It's impossible to estimate
3211runtime of the following groups (if any).
36214730
SW
3212
3213..
3214 Example output was based on the following:
3215 TZ=UTC fio --iodepth=16 --ioengine=posixaio --filename=/tmp/fiofile \
3216 --direct=1 --size=100M --time_based --runtime=50s --rate_iops=89 \
3217 --bs=7K --name=Client1 --rw=write
3218
3219When fio is done (or interrupted by :kbd:`Ctrl-C`), it will show the data for
3220each thread, group of threads, and disks in that order. For each overall thread (or
3221group) the output looks like::
3222
3223 Client1: (groupid=0, jobs=1): err= 0: pid=16109: Sat Jun 24 12:07:54 2017
3224 write: IOPS=88, BW=623KiB/s (638kB/s)(30.4MiB/50032msec)
3225 slat (nsec): min=500, max=145500, avg=8318.00, stdev=4781.50
3226 clat (usec): min=170, max=78367, avg=4019.02, stdev=8293.31
3227 lat (usec): min=174, max=78375, avg=4027.34, stdev=8291.79
3228 clat percentiles (usec):
3229 | 1.00th=[ 302], 5.00th=[ 326], 10.00th=[ 343], 20.00th=[ 363],
3230 | 30.00th=[ 392], 40.00th=[ 404], 50.00th=[ 416], 60.00th=[ 445],
3231 | 70.00th=[ 816], 80.00th=[ 6718], 90.00th=[12911], 95.00th=[21627],
3232 | 99.00th=[43779], 99.50th=[51643], 99.90th=[68682], 99.95th=[72877],
3233 | 99.99th=[78119]
3234 bw ( KiB/s): min= 532, max= 686, per=0.10%, avg=622.87, stdev=24.82, samples= 100
3235 iops : min= 76, max= 98, avg=88.98, stdev= 3.54, samples= 100
29092211
VF
3236 lat (usec) : 250=0.04%, 500=64.11%, 750=4.81%, 1000=2.79%
3237 lat (msec) : 2=4.16%, 4=1.84%, 10=4.90%, 20=11.33%, 50=5.37%
3238 lat (msec) : 100=0.65%
36214730
SW
3239 cpu : usr=0.27%, sys=0.18%, ctx=12072, majf=0, minf=21
3240 IO depths : 1=85.0%, 2=13.1%, 4=1.8%, 8=0.1%, 16=0.0%, 32=0.0%, >=64=0.0%
3241 submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
3242 complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
3243 issued rwt: total=0,4450,0, short=0,0,0, dropped=0,0,0
3244 latency : target=0, window=0, percentile=100.00%, depth=8
3245
3246The job name (or first job's name when using :option:`group_reporting`) is printed,
3247along with the group id, count of jobs being aggregated, last error id seen (which
3248is 0 when there are no errors), pid/tid of that thread and the time the job/group
3249completed. Below are the I/O statistics for each data direction performed (showing
3250writes in the example above). In the order listed, they denote:
3251
3252**read/write/trim**
3253 The string before the colon shows the I/O direction the statistics
3254 are for. **IOPS** is the average I/Os performed per second. **BW**
3255 is the average bandwidth rate shown as: value in power of 2 format
3256 (value in power of 10 format). The last two values show: (**total
3257 I/O performed** in power of 2 format / **runtime** of that thread).
f80dba8d
MT
3258
3259**slat**
36214730
SW
3260 Submission latency (**min** being the minimum, **max** being the
3261 maximum, **avg** being the average, **stdev** being the standard
3262 deviation). This is the time it took to submit the I/O. For
3263 sync I/O this row is not displayed as the slat is really the
3264 completion latency (since queue/complete is one operation there).
3265 This value can be in nanoseconds, microseconds or milliseconds ---
3266 fio will choose the most appropriate base and print that (in the
3267 example above nanoseconds was the best scale). Note: in :option:`--minimal` mode
0d237712 3268 latencies are always expressed in microseconds.
f80dba8d
MT
3269
3270**clat**
3271 Completion latency. Same names as slat, this denotes the time from
3272 submission to completion of the I/O pieces. For sync I/O, clat will
3273 usually be equal (or very close) to 0, as the time from submit to
3274 complete is basically just CPU time (I/O has already been done, see slat
3275 explanation).
3276
29092211
VF
3277**lat**
3278 Total latency. Same names as slat and clat, this denotes the time from
3279 when fio created the I/O unit to completion of the I/O operation.
3280
f80dba8d 3281**bw**
36214730
SW
3282 Bandwidth statistics based on samples. Same names as the xlat stats,
3283 but also includes the number of samples taken (**samples**) and an
3284 approximate percentage of total aggregate bandwidth this thread
3285 received in its group (**per**). This last value is only really
3286 useful if the threads in this group are on the same disk, since they
3287 are then competing for disk access.
3288
3289**iops**
3290 IOPS statistics based on samples. Same names as bw.
f80dba8d 3291
29092211
VF
3292**lat (nsec/usec/msec)**
3293 The distribution of I/O completion latencies. This is the time from when
3294 I/O leaves fio and when it gets completed. Unlike the separate
3295 read/write/trim sections above, the data here and in the remaining
3296 sections apply to all I/Os for the reporting group. 250=0.04% means that
3297 0.04% of the I/Os completed in under 250us. 500=64.11% means that 64.11%
3298 of the I/Os required 250 to 499us for completion.
3299
f80dba8d
MT
3300**cpu**
3301 CPU usage. User and system time, along with the number of context
3302 switches this thread went through, usage of system and user time, and
3303 finally the number of major and minor page faults. The CPU utilization
3304 numbers are averages for the jobs in that reporting group, while the
23a8e176 3305 context and fault counters are summed.
f80dba8d
MT
3306
3307**IO depths**
a2140525
SW
3308 The distribution of I/O depths over the job lifetime. The numbers are
3309 divided into powers of 2 and each entry covers depths from that value
3310 up to those that are lower than the next entry -- e.g., 16= covers
3311 depths from 16 to 31. Note that the range covered by a depth
3312 distribution entry can be different to the range covered by the
3313 equivalent submit/complete distribution entry.
f80dba8d
MT
3314
3315**IO submit**
3316 How many pieces of I/O were submitting in a single submit call. Each
c60ebc45 3317 entry denotes that amount and below, until the previous entry -- e.g.,
a2140525
SW
3318 16=100% means that we submitted anywhere between 9 to 16 I/Os per submit
3319 call. Note that the range covered by a submit distribution entry can
3320 be different to the range covered by the equivalent depth distribution
3321 entry.
f80dba8d
MT
3322
3323**IO complete**
3324 Like the above submit number, but for completions instead.
3325
36214730
SW
3326**IO issued rwt**
3327 The number of read/write/trim requests issued, and how many of them were
3328 short or dropped.
f80dba8d 3329
29092211 3330**IO latency**
ee21ebee 3331 These values are for :option:`latency_target` and related options. When
29092211
VF
3332 these options are engaged, this section describes the I/O depth required
3333 to meet the specified latency target.
71bfa161 3334
36214730
SW
3335..
3336 Example output was based on the following:
3337 TZ=UTC fio --ioengine=null --iodepth=2 --size=100M --numjobs=2 \
3338 --rate_process=poisson --io_limit=32M --name=read --bs=128k \
3339 --rate=11M --name=write --rw=write --bs=2k --rate=700k
3340
71bfa161 3341After each client has been listed, the group statistics are printed. They
f80dba8d 3342will look like this::
71bfa161 3343
f80dba8d 3344 Run status group 0 (all jobs):
36214730
SW
3345 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
3346 WRITE: bw=1231KiB/s (1261kB/s), 616KiB/s-621KiB/s (630kB/s-636kB/s), io=64.0MiB (67.1MB), run=52747-53223msec
71bfa161 3347
36214730 3348For each data direction it prints:
71bfa161 3349
36214730
SW
3350**bw**
3351 Aggregate bandwidth of threads in this group followed by the
3352 minimum and maximum bandwidth of all the threads in this group.
3353 Values outside of brackets are power-of-2 format and those
3354 within are the equivalent value in a power-of-10 format.
f80dba8d 3355**io**
36214730
SW
3356 Aggregate I/O performed of all threads in this group. The
3357 format is the same as bw.
3358**run**
3359 The smallest and longest runtimes of the threads in this group.
71bfa161 3360
f50fbdda 3361And finally, the disk statistics are printed. This is Linux specific. They will look like this::
71bfa161 3362
f80dba8d
MT
3363 Disk stats (read/write):
3364 sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00%
71bfa161
JA
3365
3366Each value is printed for both reads and writes, with reads first. The
3367numbers denote:
3368
f80dba8d 3369**ios**
c60ebc45 3370 Number of I/Os performed by all groups.
f80dba8d 3371**merge**
007c7be9 3372 Number of merges performed by the I/O scheduler.
f80dba8d
MT
3373**ticks**
3374 Number of ticks we kept the disk busy.
36214730 3375**in_queue**
f80dba8d
MT
3376 Total time spent in the disk queue.
3377**util**
3378 The disk utilization. A value of 100% means we kept the disk
71bfa161
JA
3379 busy constantly, 50% would be a disk idling half of the time.
3380
f80dba8d
MT
3381It is also possible to get fio to dump the current output while it is running,
3382without terminating the job. To do that, send fio the **USR1** signal. You can
3383also get regularly timed dumps by using the :option:`--status-interval`
3384parameter, or by creating a file in :file:`/tmp` named
3385:file:`fio-dump-status`. If fio sees this file, it will unlink it and dump the
3386current output status.
8423bd11 3387
71bfa161 3388
f80dba8d
MT
3389Terse output
3390------------
71bfa161 3391
f80dba8d
MT
3392For scripted usage where you typically want to generate tables or graphs of the
3393results, fio can output the results in a semicolon separated format. The format
3394is one long line of values, such as::
71bfa161 3395
f80dba8d
MT
3396 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%
3397 A description of this job goes here.
562c2d2f
DN
3398
3399The job description (if provided) follows on a second line.
71bfa161 3400
a7f77fa6
SW
3401To enable terse output, use the :option:`--minimal` or
3402:option:`--output-format`\=terse command line options. The
f80dba8d
MT
3403first value is the version of the terse output format. If the output has to be
3404changed for some reason, this number will be incremented by 1 to signify that
3405change.
6820cb3b 3406
a2c95580 3407Split up, the format is as follows (comments in brackets denote when a
007c7be9 3408field was introduced or whether it's specific to some terse version):
71bfa161 3409
f80dba8d
MT
3410 ::
3411
f50fbdda 3412 terse version, fio version [v3], jobname, groupid, error
f80dba8d
MT
3413
3414 READ status::
3415
3416 Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
3417 Submission latency: min, max, mean, stdev (usec)
3418 Completion latency: min, max, mean, stdev (usec)
3419 Completion latency percentiles: 20 fields (see below)
3420 Total latency: min, max, mean, stdev (usec)
f50fbdda
TK
3421 Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
3422 IOPS [v5]: min, max, mean, stdev, number of samples
f80dba8d
MT
3423
3424 WRITE status:
3425
3426 ::
3427
3428 Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
3429 Submission latency: min, max, mean, stdev (usec)
247823cc 3430 Completion latency: min, max, mean, stdev (usec)
f80dba8d
MT
3431 Completion latency percentiles: 20 fields (see below)
3432 Total latency: min, max, mean, stdev (usec)
f50fbdda
TK
3433 Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
3434 IOPS [v5]: min, max, mean, stdev, number of samples
a2c95580
AH
3435
3436 TRIM status [all but version 3]:
3437
f50fbdda 3438 Fields are similar to READ/WRITE status.
f80dba8d
MT
3439
3440 CPU usage::
3441
3442 user, system, context switches, major faults, minor faults
3443
3444 I/O depths::
3445
3446 <=1, 2, 4, 8, 16, 32, >=64
3447
3448 I/O latencies microseconds::
3449
3450 <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
3451
3452 I/O latencies milliseconds::
3453
3454 <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
3455
a2c95580 3456 Disk utilization [v3]::
f80dba8d 3457
f50fbdda
TK
3458 disk name, read ios, write ios, read merges, write merges, read ticks, write ticks,
3459 time spent in queue, disk utilization percentage
f80dba8d
MT
3460
3461 Additional Info (dependent on continue_on_error, default off)::
3462
3463 total # errors, first error code
3464
3465 Additional Info (dependent on description being set)::
3466
3467 Text description
3468
3469Completion latency percentiles can be a grouping of up to 20 sets, so for the
3470terse output fio writes all of them. Each field will look like this::
1db92cb6 3471
f50fbdda 3472 1.00%=6112
1db92cb6 3473
f80dba8d 3474which is the Xth percentile, and the `usec` latency associated with it.
1db92cb6 3475
f50fbdda 3476For `Disk utilization`, all disks used by fio are shown. So for each disk there
f80dba8d 3477will be a disk utilization section.
f2f788dd 3478
2fc26c3d 3479Below is a single line containing short names for each of the fields in the
2831be97 3480minimal output v3, separated by semicolons::
2fc26c3d 3481
f50fbdda 3482 terse_version_3;fio_version;jobname;groupid;error;read_kb;read_bandwidth;read_iops;read_runtime_ms;read_slat_min;read_slat_max;read_slat_mean;read_slat_dev;read_clat_min;read_clat_max;read_clat_mean;read_clat_dev;read_clat_pct01;read_clat_pct02;read_clat_pct03;read_clat_pct04;read_clat_pct05;read_clat_pct06;read_clat_pct07;read_clat_pct08;read_clat_pct09;read_clat_pct10;read_clat_pct11;read_clat_pct12;read_clat_pct13;read_clat_pct14;read_clat_pct15;read_clat_pct16;read_clat_pct17;read_clat_pct18;read_clat_pct19;read_clat_pct20;read_tlat_min;read_lat_max;read_lat_mean;read_lat_dev;read_bw_min;read_bw_max;read_bw_agg_pct;read_bw_mean;read_bw_dev;write_kb;write_bandwidth;write_iops;write_runtime_ms;write_slat_min;write_slat_max;write_slat_mean;write_slat_dev;write_clat_min;write_clat_max;write_clat_mean;write_clat_dev;write_clat_pct01;write_clat_pct02;write_clat_pct03;write_clat_pct04;write_clat_pct05;write_clat_pct06;write_clat_pct07;write_clat_pct08;write_clat_pct09;write_clat_pct10;write_clat_pct11;write_clat_pct12;write_clat_pct13;write_clat_pct14;write_clat_pct15;write_clat_pct16;write_clat_pct17;write_clat_pct18;write_clat_pct19;write_clat_pct20;write_tlat_min;write_lat_max;write_lat_mean;write_lat_dev;write_bw_min;write_bw_max;write_bw_agg_pct;write_bw_mean;write_bw_dev;cpu_user;cpu_sys;cpu_csw;cpu_mjf;cpu_minf;iodepth_1;iodepth_2;iodepth_4;iodepth_8;iodepth_16;iodepth_32;iodepth_64;lat_2us;lat_4us;lat_10us;lat_20us;lat_50us;lat_100us;lat_250us;lat_500us;lat_750us;lat_1000us;lat_2ms;lat_4ms;lat_10ms;lat_20ms;lat_50ms;lat_100ms;lat_250ms;lat_500ms;lat_750ms;lat_1000ms;lat_2000ms;lat_over_2000ms;disk_name;disk_read_iops;disk_write_iops;disk_read_merges;disk_write_merges;disk_read_ticks;write_ticks;disk_queue_time;disk_util
2fc26c3d 3483
25c8b9d7 3484
44c82dba
VF
3485JSON output
3486------------
3487
3488The `json` output format is intended to be both human readable and convenient
3489for automated parsing. For the most part its sections mirror those of the
3490`normal` output. The `runtime` value is reported in msec and the `bw` value is
3491reported in 1024 bytes per second units.
3492
3493
d29c4a91
VF
3494JSON+ output
3495------------
3496
3497The `json+` output format is identical to the `json` output format except that it
3498adds a full dump of the completion latency bins. Each `bins` object contains a
3499set of (key, value) pairs where keys are latency durations and values count how
3500many I/Os had completion latencies of the corresponding duration. For example,
3501consider:
3502
3503 "bins" : { "87552" : 1, "89600" : 1, "94720" : 1, "96768" : 1, "97792" : 1, "99840" : 1, "100864" : 2, "103936" : 6, "104960" : 534, "105984" : 5995, "107008" : 7529, ... }
3504
3505This data indicates that one I/O required 87,552ns to complete, two I/Os required
3506100,864ns to complete, and 7529 I/Os required 107,008ns to complete.
3507
3508Also included with fio is a Python script `fio_jsonplus_clat2csv` that takes
3509json+ output and generates CSV-formatted latency data suitable for plotting.
3510
3511The latency durations actually represent the midpoints of latency intervals.
f50fbdda 3512For details refer to :file:`stat.h`.
d29c4a91
VF
3513
3514
f80dba8d
MT
3515Trace file format
3516-----------------
3517
3518There are two trace file format that you can encounter. The older (v1) format is
3519unsupported since version 1.20-rc3 (March 2008). It will still be described
25c8b9d7
PD
3520below in case that you get an old trace and want to understand it.
3521
3522In any case the trace is a simple text file with a single action per line.
3523
3524
f80dba8d
MT
3525Trace file format v1
3526~~~~~~~~~~~~~~~~~~~~
3527
3528Each line represents a single I/O action in the following format::
3529
3530 rw, offset, length
25c8b9d7 3531
f50fbdda 3532where `rw=0/1` for read/write, and the `offset` and `length` entries being in bytes.
25c8b9d7 3533
22413915 3534This format is not supported in fio versions >= 1.20-rc3.
25c8b9d7 3535
25c8b9d7 3536
f80dba8d
MT
3537Trace file format v2
3538~~~~~~~~~~~~~~~~~~~~
25c8b9d7 3539
f80dba8d
MT
3540The second version of the trace file format was added in fio version 1.17. It
3541allows to access more then one file per trace and has a bigger set of possible
3542file actions.
25c8b9d7 3543
f80dba8d 3544The first line of the trace file has to be::
25c8b9d7 3545
f80dba8d 3546 fio version 2 iolog
25c8b9d7
PD
3547
3548Following this can be lines in two different formats, which are described below.
3549
f80dba8d 3550The file management format::
25c8b9d7 3551
f80dba8d 3552 filename action
25c8b9d7 3553
f50fbdda 3554The `filename` is given as an absolute path. The `action` can be one of these:
25c8b9d7 3555
f80dba8d 3556**add**
f50fbdda 3557 Add the given `filename` to the trace.
f80dba8d 3558**open**
f50fbdda 3559 Open the file with the given `filename`. The `filename` has to have
f80dba8d
MT
3560 been added with the **add** action before.
3561**close**
f50fbdda 3562 Close the file with the given `filename`. The file has to have been
f80dba8d
MT
3563 opened before.
3564
3565
3566The file I/O action format::
3567
3568 filename action offset length
3569
3570The `filename` is given as an absolute path, and has to have been added and
3571opened before it can be used with this format. The `offset` and `length` are
3572given in bytes. The `action` can be one of these:
3573
3574**wait**
3575 Wait for `offset` microseconds. Everything below 100 is discarded.
3576 The time is relative to the previous `wait` statement.
3577**read**
3578 Read `length` bytes beginning from `offset`.
3579**write**
3580 Write `length` bytes beginning from `offset`.
3581**sync**
3582 :manpage:`fsync(2)` the file.
3583**datasync**
3584 :manpage:`fdatasync(2)` the file.
3585**trim**
3586 Trim the given file from the given `offset` for `length` bytes.
3587
3588CPU idleness profiling
3589----------------------
3590
3591In some cases, we want to understand CPU overhead in a test. For example, we
3592test patches for the specific goodness of whether they reduce CPU usage.
3593Fio implements a balloon approach to create a thread per CPU that runs at idle
3594priority, meaning that it only runs when nobody else needs the cpu.
3595By measuring the amount of work completed by the thread, idleness of each CPU
3596can be derived accordingly.
3597
3598An unit work is defined as touching a full page of unsigned characters. Mean and
3599standard deviation of time to complete an unit work is reported in "unit work"
3600section. Options can be chosen to report detailed percpu idleness or overall
3601system idleness by aggregating percpu stats.
3602
3603
3604Verification and triggers
3605-------------------------
3606
3607Fio is usually run in one of two ways, when data verification is done. The first
3608is a normal write job of some sort with verify enabled. When the write phase has
3609completed, fio switches to reads and verifies everything it wrote. The second
3610model is running just the write phase, and then later on running the same job
3611(but with reads instead of writes) to repeat the same I/O patterns and verify
3612the contents. Both of these methods depend on the write phase being completed,
3613as fio otherwise has no idea how much data was written.
3614
3615With verification triggers, fio supports dumping the current write state to
3616local files. Then a subsequent read verify workload can load this state and know
3617exactly where to stop. This is useful for testing cases where power is cut to a
3618server in a managed fashion, for instance.
99b9a85a
JA
3619
3620A verification trigger consists of two things:
3621
f80dba8d
MT
36221) Storing the write state of each job.
36232) Executing a trigger command.
99b9a85a 3624
f80dba8d
MT
3625The write state is relatively small, on the order of hundreds of bytes to single
3626kilobytes. It contains information on the number of completions done, the last X
3627completions, etc.
99b9a85a 3628
f80dba8d
MT
3629A trigger is invoked either through creation ('touch') of a specified file in
3630the system, or through a timeout setting. If fio is run with
9207a0cb 3631:option:`--trigger-file`\= :file:`/tmp/trigger-file`, then it will continually
f80dba8d
MT
3632check for the existence of :file:`/tmp/trigger-file`. When it sees this file, it
3633will fire off the trigger (thus saving state, and executing the trigger
99b9a85a
JA
3634command).
3635
f80dba8d
MT
3636For client/server runs, there's both a local and remote trigger. If fio is
3637running as a server backend, it will send the job states back to the client for
3638safe storage, then execute the remote trigger, if specified. If a local trigger
3639is specified, the server will still send back the write state, but the client
3640will then execute the trigger.
99b9a85a 3641
f80dba8d
MT
3642Verification trigger example
3643~~~~~~~~~~~~~~~~~~~~~~~~~~~~
99b9a85a 3644
f50fbdda
TK
3645Let's say we want to run a powercut test on the remote Linux machine 'server'.
3646Our write workload is in :file:`write-test.fio`. We want to cut power to 'server' at
f80dba8d
MT
3647some point during the run, and we'll run this test from the safety or our local
3648machine, 'localbox'. On the server, we'll start the fio backend normally::
99b9a85a 3649
f80dba8d 3650 server# fio --server
99b9a85a 3651
f80dba8d 3652and on the client, we'll fire off the workload::
99b9a85a 3653
f80dba8d 3654 localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger-remote="bash -c \"echo b > /proc/sysrq-triger\""
99b9a85a 3655
f80dba8d 3656We set :file:`/tmp/my-trigger` as the trigger file, and we tell fio to execute::
99b9a85a 3657
f80dba8d 3658 echo b > /proc/sysrq-trigger
99b9a85a 3659
f80dba8d
MT
3660on the server once it has received the trigger and sent us the write state. This
3661will work, but it's not **really** cutting power to the server, it's merely
3662abruptly rebooting it. If we have a remote way of cutting power to the server
3663through IPMI or similar, we could do that through a local trigger command
4502cb42 3664instead. Let's assume we have a script that does IPMI reboot of a given hostname,
f80dba8d
MT
3665ipmi-reboot. On localbox, we could then have run fio with a local trigger
3666instead::
99b9a85a 3667
f80dba8d 3668 localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger="ipmi-reboot server"
99b9a85a 3669
f80dba8d
MT
3670For this case, fio would wait for the server to send us the write state, then
3671execute ``ipmi-reboot server`` when that happened.
3672
3673Loading verify state
3674~~~~~~~~~~~~~~~~~~~~
3675
4502cb42 3676To load stored write state, a read verification job file must contain the
f80dba8d 3677:option:`verify_state_load` option. If that is set, fio will load the previously
99b9a85a 3678stored state. For a local fio run this is done by loading the files directly,
f80dba8d
MT
3679and on a client/server run, the server backend will ask the client to send the
3680files over and load them from there.
a3ae5b05
JA
3681
3682
f80dba8d
MT
3683Log File Formats
3684----------------
a3ae5b05
JA
3685
3686Fio supports a variety of log file formats, for logging latencies, bandwidth,
3687and IOPS. The logs share a common format, which looks like this:
3688
5a83478f
SW
3689 *time* (`msec`), *value*, *data direction*, *block size* (`bytes`),
3690 *offset* (`bytes`)
a3ae5b05 3691
5a83478f 3692*Time* for the log entry is always in milliseconds. The *value* logged depends
a3ae5b05
JA
3693on the type of log, it will be one of the following:
3694
f80dba8d 3695 **Latency log**
168bb587 3696 Value is latency in nsecs
f80dba8d
MT
3697 **Bandwidth log**
3698 Value is in KiB/sec
3699 **IOPS log**
3700 Value is IOPS
3701
3702*Data direction* is one of the following:
3703
3704 **0**
3705 I/O is a READ
3706 **1**
3707 I/O is a WRITE
3708 **2**
3709 I/O is a TRIM
3710
5a83478f
SW
3711The entry's *block size* is always in bytes. The *offset* is the offset, in bytes,
3712from the start of the file, for that particular I/O. The logging of the offset can be
3713toggled with :option:`log_offset`.
f80dba8d 3714
6fc82095 3715Fio defaults to logging every individual I/O. When IOPS are logged for individual
5a83478f 3716I/Os the *value* entry will always be 1. If windowed logging is enabled through
6fc82095
SW
3717:option:`log_avg_msec`, fio logs the average values over the specified period of time.
3718If windowed logging is enabled and :option:`log_max_value` is set, then fio logs
5a83478f
SW
3719maximum values in that window instead of averages. Since *data direction*, *block
3720size* and *offset* are per-I/O values, if windowed logging is enabled they
3721aren't applicable and will be 0.
f80dba8d 3722
b8f7e412 3723Client/Server
f80dba8d
MT
3724-------------
3725
3726Normally fio is invoked as a stand-alone application on the machine where the
6cf30ac0
SW
3727I/O workload should be generated. However, the backend and frontend of fio can
3728be run separately i.e., the fio server can generate an I/O workload on the "Device
3729Under Test" while being controlled by a client on another machine.
f80dba8d
MT
3730
3731Start the server on the machine which has access to the storage DUT::
3732
f50fbdda 3733 $ fio --server=args
f80dba8d 3734
dbb257bb 3735where `args` defines what fio listens to. The arguments are of the form
f80dba8d
MT
3736``type,hostname`` or ``IP,port``. *type* is either ``ip`` (or ip4) for TCP/IP
3737v4, ``ip6`` for TCP/IP v6, or ``sock`` for a local unix domain socket.
3738*hostname* is either a hostname or IP address, and *port* is the port to listen
3739to (only valid for TCP/IP, not a local socket). Some examples:
3740
37411) ``fio --server``
3742
3743 Start a fio server, listening on all interfaces on the default port (8765).
3744
37452) ``fio --server=ip:hostname,4444``
3746
3747 Start a fio server, listening on IP belonging to hostname and on port 4444.
3748
37493) ``fio --server=ip6:::1,4444``
3750
3751 Start a fio server, listening on IPv6 localhost ::1 and on port 4444.
3752
37534) ``fio --server=,4444``
3754
3755 Start a fio server, listening on all interfaces on port 4444.
3756
37575) ``fio --server=1.2.3.4``
3758
3759 Start a fio server, listening on IP 1.2.3.4 on the default port.
3760
37616) ``fio --server=sock:/tmp/fio.sock``
3762
dbb257bb 3763 Start a fio server, listening on the local socket :file:`/tmp/fio.sock`.
f80dba8d
MT
3764
3765Once a server is running, a "client" can connect to the fio server with::
3766
3767 fio <local-args> --client=<server> <remote-args> <job file(s)>
3768
3769where `local-args` are arguments for the client where it is running, `server`
3770is the connect string, and `remote-args` and `job file(s)` are sent to the
3771server. The `server` string follows the same format as it does on the server
3772side, to allow IP/hostname/socket and port strings.
3773
3774Fio can connect to multiple servers this way::
3775
3776 fio --client=<server1> <job file(s)> --client=<server2> <job file(s)>
3777
3778If the job file is located on the fio server, then you can tell the server to
3779load a local file as well. This is done by using :option:`--remote-config` ::
3780
3781 fio --client=server --remote-config /path/to/file.fio
3782
3783Then fio will open this local (to the server) job file instead of being passed
3784one from the client.
3785
3786If you have many servers (example: 100 VMs/containers), you can input a pathname
3787of a file containing host IPs/names as the parameter value for the
3788:option:`--client` option. For example, here is an example :file:`host.list`
3789file containing 2 hostnames::
3790
3791 host1.your.dns.domain
3792 host2.your.dns.domain
3793
3794The fio command would then be::
a3ae5b05 3795
f80dba8d 3796 fio --client=host.list <job file(s)>
a3ae5b05