client: use temp buffer for single output flush for json/disk util
[fio.git] / HOWTO
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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
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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*
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97 Show available debug options.
98
99.. option:: --parse-only
100
25cd4b95 101 Parse options only, don't start any I/O.
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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
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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
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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
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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).
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131
132.. option:: --version
133
b8f7e412 134 Print version information and exit.
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135
136.. option:: --help
137
113f0e7c 138 Print a summary of the command line options and exit.
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139
140.. option:: --cpuclock-test
141
142 Perform test and validation of internal CPU clock.
143
113f0e7c 144.. option:: --crctest=[test]
f80dba8d 145
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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.
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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
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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.
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159
160.. option:: --showcmd=jobfile
161
b8f7e412 162 Convert `jobfile` to a set of command-line options.
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163
164.. option:: --readonly
165
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166 Turn on safety read-only checks, preventing writes and trims. The
167 ``--readonly`` option is an extra safety guard to prevent users from
168 accidentally starting a write or trim workload when that is not desired.
169 Fio will only modify the device under test if
170 `rw=write/randwrite/rw/randrw/trim/randtrim/trimwrite` is given. This
171 safety net can be used as an extra precaution.
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172
173.. option:: --eta=when
174
b8f7e412 175 Specifies when real-time ETA estimate should be printed. `when` may be
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176 `always`, `never` or `auto`. `auto` is the default, it prints ETA
177 when requested if the output is a TTY. `always` disregards the output
178 type, and prints ETA when requested. `never` never prints ETA.
179
180.. option:: --eta-interval=time
181
182 By default, fio requests client ETA status roughly every second. With
183 this option, the interval is configurable. Fio imposes a minimum
184 allowed time to avoid flooding the console, less than 250 msec is
185 not supported.
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186
187.. option:: --eta-newline=time
188
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189 Force a new line for every `time` period passed. When the unit is omitted,
190 the value is interpreted in seconds.
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191
192.. option:: --status-interval=time
193
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194 Force a full status dump of cumulative (from job start) values at `time`
195 intervals. This option does *not* provide per-period measurements. So
196 values such as bandwidth are running averages. When the time unit is omitted,
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197 `time` is interpreted in seconds. Note that using this option with
198 ``--output-format=json`` will yield output that technically isn't valid
199 json, since the output will be collated sets of valid json. It will need
200 to be split into valid sets of json after the run.
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201
202.. option:: --section=name
203
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204 Only run specified section `name` in job file. Multiple sections can be specified.
205 The ``--section`` option allows one to combine related jobs into one file.
206 E.g. one job file could define light, moderate, and heavy sections. Tell
207 fio to run only the "heavy" section by giving ``--section=heavy``
208 command line option. One can also specify the "write" operations in one
209 section and "verify" operation in another section. The ``--section`` option
210 only applies to job sections. The reserved *global* section is always
211 parsed and used.
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212
213.. option:: --alloc-size=kb
214
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215 Set the internal smalloc pool size to `kb` in KiB. The
216 ``--alloc-size`` switch allows one to use a larger pool size for smalloc.
217 If running large jobs with randommap enabled, fio can run out of memory.
218 Smalloc is an internal allocator for shared structures from a fixed size
219 memory pool and can grow to 16 pools. The pool size defaults to 16MiB.
f80dba8d 220
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221 NOTE: While running :file:`.fio_smalloc.*` backing store files are visible
222 in :file:`/tmp`.
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223
224.. option:: --warnings-fatal
225
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226 All fio parser warnings are fatal, causing fio to exit with an
227 error.
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228
229.. option:: --max-jobs=nr
230
f50fbdda 231 Set the maximum number of threads/processes to support to `nr`.
818322cc 232 NOTE: On Linux, it may be necessary to increase the shared-memory
71aa48eb 233 limit (:file:`/proc/sys/kernel/shmmax`) if fio runs into errors while
818322cc 234 creating jobs.
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235
236.. option:: --server=args
237
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238 Start a backend server, with `args` specifying what to listen to.
239 See `Client/Server`_ section.
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240
241.. option:: --daemonize=pidfile
242
b034c0dd 243 Background a fio server, writing the pid to the given `pidfile` file.
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244
245.. option:: --client=hostname
246
f50fbdda 247 Instead of running the jobs locally, send and run them on the given `hostname`
71aa48eb 248 or set of `hostname`\s. See `Client/Server`_ section.
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249
250.. option:: --remote-config=file
251
f50fbdda 252 Tell fio server to load this local `file`.
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253
254.. option:: --idle-prof=option
255
b8f7e412 256 Report CPU idleness. `option` is one of the following:
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257
258 **calibrate**
259 Run unit work calibration only and exit.
260
261 **system**
262 Show aggregate system idleness and unit work.
263
264 **percpu**
265 As **system** but also show per CPU idleness.
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266
267.. option:: --inflate-log=log
268
f50fbdda 269 Inflate and output compressed `log`.
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270
271.. option:: --trigger-file=file
272
f50fbdda 273 Execute trigger command when `file` exists.
f80dba8d 274
f50fbdda 275.. option:: --trigger-timeout=time
f80dba8d 276
f50fbdda 277 Execute trigger at this `time`.
f80dba8d 278
f50fbdda 279.. option:: --trigger=command
f80dba8d 280
f50fbdda 281 Set this `command` as local trigger.
f80dba8d 282
f50fbdda 283.. option:: --trigger-remote=command
f80dba8d 284
f50fbdda 285 Set this `command` as remote trigger.
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286
287.. option:: --aux-path=path
288
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289 Use the directory specified by `path` for generated state files instead
290 of the current working directory.
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291
292Any parameters following the options will be assumed to be job files, unless
293they match a job file parameter. Multiple job files can be listed and each job
294file will be regarded as a separate group. Fio will :option:`stonewall`
295execution between each group.
296
297
298Job file format
299---------------
300
301As previously described, fio accepts one or more job files describing what it is
302supposed to do. The job file format is the classic ini file, where the names
c60ebc45 303enclosed in [] brackets define the job name. You are free to use any ASCII name
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304you want, except *global* which has special meaning. Following the job name is
305a sequence of zero or more parameters, one per line, that define the behavior of
306the job. If the first character in a line is a ';' or a '#', the entire line is
307discarded as a comment.
308
309A *global* section sets defaults for the jobs described in that file. A job may
310override a *global* section parameter, and a job file may even have several
311*global* sections if so desired. A job is only affected by a *global* section
312residing above it.
313
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314The :option:`--cmdhelp` option also lists all options. If used with a `command`
315argument, :option:`--cmdhelp` will detail the given `command`.
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316
317See the `examples/` directory for inspiration on how to write job files. Note
318the copyright and license requirements currently apply to `examples/` files.
319
320So let's look at a really simple job file that defines two processes, each
321randomly reading from a 128MiB file:
322
323.. code-block:: ini
324
325 ; -- start job file --
326 [global]
327 rw=randread
328 size=128m
329
330 [job1]
331
332 [job2]
333
334 ; -- end job file --
335
336As you can see, the job file sections themselves are empty as all the described
337parameters are shared. As no :option:`filename` option is given, fio makes up a
338`filename` for each of the jobs as it sees fit. On the command line, this job
339would look as follows::
340
341$ fio --name=global --rw=randread --size=128m --name=job1 --name=job2
342
343
344Let's look at an example that has a number of processes writing randomly to
345files:
346
347.. code-block:: ini
348
349 ; -- start job file --
350 [random-writers]
351 ioengine=libaio
352 iodepth=4
353 rw=randwrite
354 bs=32k
355 direct=0
356 size=64m
357 numjobs=4
358 ; -- end job file --
359
360Here we have no *global* section, as we only have one job defined anyway. We
361want to use async I/O here, with a depth of 4 for each file. We also increased
362the buffer size used to 32KiB and define numjobs to 4 to fork 4 identical
363jobs. The result is 4 processes each randomly writing to their own 64MiB
364file. Instead of using the above job file, you could have given the parameters
365on the command line. For this case, you would specify::
366
367$ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4
368
369When fio is utilized as a basis of any reasonably large test suite, it might be
370desirable to share a set of standardized settings across multiple job files.
371Instead of copy/pasting such settings, any section may pull in an external
372:file:`filename.fio` file with *include filename* directive, as in the following
373example::
374
375 ; -- start job file including.fio --
376 [global]
377 filename=/tmp/test
378 filesize=1m
379 include glob-include.fio
380
381 [test]
382 rw=randread
383 bs=4k
384 time_based=1
385 runtime=10
386 include test-include.fio
387 ; -- end job file including.fio --
388
389.. code-block:: ini
390
391 ; -- start job file glob-include.fio --
392 thread=1
393 group_reporting=1
394 ; -- end job file glob-include.fio --
395
396.. code-block:: ini
397
398 ; -- start job file test-include.fio --
399 ioengine=libaio
400 iodepth=4
401 ; -- end job file test-include.fio --
402
403Settings pulled into a section apply to that section only (except *global*
404section). Include directives may be nested in that any included file may contain
405further include directive(s). Include files may not contain [] sections.
406
407
408Environment variables
409~~~~~~~~~~~~~~~~~~~~~
410
411Fio also supports environment variable expansion in job files. Any sub-string of
412the form ``${VARNAME}`` as part of an option value (in other words, on the right
413of the '='), will be expanded to the value of the environment variable called
414`VARNAME`. If no such environment variable is defined, or `VARNAME` is the
415empty string, the empty string will be substituted.
416
417As an example, let's look at a sample fio invocation and job file::
418
419$ SIZE=64m NUMJOBS=4 fio jobfile.fio
420
421.. code-block:: ini
422
423 ; -- start job file --
424 [random-writers]
425 rw=randwrite
426 size=${SIZE}
427 numjobs=${NUMJOBS}
428 ; -- end job file --
429
430This will expand to the following equivalent job file at runtime:
431
432.. code-block:: ini
433
434 ; -- start job file --
435 [random-writers]
436 rw=randwrite
437 size=64m
438 numjobs=4
439 ; -- end job file --
440
441Fio ships with a few example job files, you can also look there for inspiration.
442
443Reserved keywords
444~~~~~~~~~~~~~~~~~
445
446Additionally, fio has a set of reserved keywords that will be replaced
447internally with the appropriate value. Those keywords are:
448
449**$pagesize**
450
451 The architecture page size of the running system.
452
453**$mb_memory**
454
455 Megabytes of total memory in the system.
456
457**$ncpus**
458
459 Number of online available CPUs.
460
461These can be used on the command line or in the job file, and will be
462automatically substituted with the current system values when the job is
463run. Simple math is also supported on these keywords, so you can perform actions
464like::
465
b034c0dd 466 size=8*$mb_memory
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467
468and get that properly expanded to 8 times the size of memory in the machine.
469
470
471Job file parameters
472-------------------
473
474This section describes in details each parameter associated with a job. Some
475parameters take an option of a given type, such as an integer or a
476string. Anywhere a numeric value is required, an arithmetic expression may be
477used, provided it is surrounded by parentheses. Supported operators are:
478
479 - addition (+)
480 - subtraction (-)
481 - multiplication (*)
482 - division (/)
483 - modulus (%)
484 - exponentiation (^)
485
486For time values in expressions, units are microseconds by default. This is
487different than for time values not in expressions (not enclosed in
488parentheses). The following types are used:
489
490
491Parameter types
492~~~~~~~~~~~~~~~
493
494**str**
b034c0dd 495 String: A sequence of alphanumeric characters.
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496
497**time**
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498 Integer with possible time suffix. Without a unit value is interpreted as
499 seconds unless otherwise specified. Accepts a suffix of 'd' for days, 'h' for
500 hours, 'm' for minutes, 's' for seconds, 'ms' (or 'msec') for milliseconds and
501 'us' (or 'usec') for microseconds. For example, use 10m for 10 minutes.
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502
503.. _int:
504
505**int**
506 Integer. A whole number value, which may contain an integer prefix
507 and an integer suffix:
508
b034c0dd 509 [*integer prefix*] **number** [*integer suffix*]
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510
511 The optional *integer prefix* specifies the number's base. The default
512 is decimal. *0x* specifies hexadecimal.
513
514 The optional *integer suffix* specifies the number's units, and includes an
515 optional unit prefix and an optional unit. For quantities of data, the
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516 default unit is bytes. For quantities of time, the default unit is seconds
517 unless otherwise specified.
f80dba8d 518
9207a0cb 519 With :option:`kb_base`\=1000, fio follows international standards for unit
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520 prefixes. To specify power-of-10 decimal values defined in the
521 International System of Units (SI):
522
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523 * *K* -- means kilo (K) or 1000
524 * *M* -- means mega (M) or 1000**2
525 * *G* -- means giga (G) or 1000**3
526 * *T* -- means tera (T) or 1000**4
527 * *P* -- means peta (P) or 1000**5
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528
529 To specify power-of-2 binary values defined in IEC 80000-13:
530
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531 * *Ki* -- means kibi (Ki) or 1024
532 * *Mi* -- means mebi (Mi) or 1024**2
533 * *Gi* -- means gibi (Gi) or 1024**3
534 * *Ti* -- means tebi (Ti) or 1024**4
535 * *Pi* -- means pebi (Pi) or 1024**5
f80dba8d 536
9207a0cb 537 With :option:`kb_base`\=1024 (the default), the unit prefixes are opposite
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538 from those specified in the SI and IEC 80000-13 standards to provide
539 compatibility with old scripts. For example, 4k means 4096.
540
541 For quantities of data, an optional unit of 'B' may be included
b8f7e412 542 (e.g., 'kB' is the same as 'k').
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543
544 The *integer suffix* is not case sensitive (e.g., m/mi mean mebi/mega,
545 not milli). 'b' and 'B' both mean byte, not bit.
546
9207a0cb 547 Examples with :option:`kb_base`\=1000:
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548
549 * *4 KiB*: 4096, 4096b, 4096B, 4ki, 4kib, 4kiB, 4Ki, 4KiB
550 * *1 MiB*: 1048576, 1mi, 1024ki
551 * *1 MB*: 1000000, 1m, 1000k
552 * *1 TiB*: 1099511627776, 1ti, 1024gi, 1048576mi
553 * *1 TB*: 1000000000, 1t, 1000m, 1000000k
554
9207a0cb 555 Examples with :option:`kb_base`\=1024 (default):
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556
557 * *4 KiB*: 4096, 4096b, 4096B, 4k, 4kb, 4kB, 4K, 4KB
558 * *1 MiB*: 1048576, 1m, 1024k
559 * *1 MB*: 1000000, 1mi, 1000ki
560 * *1 TiB*: 1099511627776, 1t, 1024g, 1048576m
561 * *1 TB*: 1000000000, 1ti, 1000mi, 1000000ki
562
563 To specify times (units are not case sensitive):
564
565 * *D* -- means days
566 * *H* -- means hours
4502cb42 567 * *M* -- means minutes
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568 * *s* -- or sec means seconds (default)
569 * *ms* -- or *msec* means milliseconds
570 * *us* -- or *usec* means microseconds
571
572 If the option accepts an upper and lower range, use a colon ':' or
573 minus '-' to separate such values. See :ref:`irange <irange>`.
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574 If the lower value specified happens to be larger than the upper value
575 the two values are swapped.
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576
577.. _bool:
578
579**bool**
580 Boolean. Usually parsed as an integer, however only defined for
581 true and false (1 and 0).
582
583.. _irange:
584
585**irange**
586 Integer range with suffix. Allows value range to be given, such as
c60ebc45 587 1024-4096. A colon may also be used as the separator, e.g. 1k:4k. If the
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588 option allows two sets of ranges, they can be specified with a ',' or '/'
589 delimiter: 1k-4k/8k-32k. Also see :ref:`int <int>`.
590
591**float_list**
592 A list of floating point numbers, separated by a ':' character.
593
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594With the above in mind, here follows the complete list of fio job parameters.
595
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596
597Units
598~~~~~
599
600.. option:: kb_base=int
601
602 Select the interpretation of unit prefixes in input parameters.
603
604 **1000**
605 Inputs comply with IEC 80000-13 and the International
606 System of Units (SI). Use:
607
608 - power-of-2 values with IEC prefixes (e.g., KiB)
609 - power-of-10 values with SI prefixes (e.g., kB)
610
611 **1024**
612 Compatibility mode (default). To avoid breaking old scripts:
613
614 - power-of-2 values with SI prefixes
615 - power-of-10 values with IEC prefixes
616
617 See :option:`bs` for more details on input parameters.
618
619 Outputs always use correct prefixes. Most outputs include both
620 side-by-side, like::
621
622 bw=2383.3kB/s (2327.4KiB/s)
623
624 If only one value is reported, then kb_base selects the one to use:
625
626 **1000** -- SI prefixes
627
628 **1024** -- IEC prefixes
629
630.. option:: unit_base=int
631
632 Base unit for reporting. Allowed values are:
633
634 **0**
635 Use auto-detection (default).
636 **8**
637 Byte based.
638 **1**
639 Bit based.
640
641
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642Job description
643~~~~~~~~~~~~~~~
644
645.. option:: name=str
646
647 ASCII name of the job. This may be used to override the name printed by fio
648 for this job. Otherwise the job name is used. On the command line this
649 parameter has the special purpose of also signaling the start of a new job.
650
651.. option:: description=str
652
653 Text description of the job. Doesn't do anything except dump this text
654 description when this job is run. It's not parsed.
655
656.. option:: loops=int
657
658 Run the specified number of iterations of this job. Used to repeat the same
659 workload a given number of times. Defaults to 1.
660
661.. option:: numjobs=int
662
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663 Create the specified number of clones of this job. Each clone of job
664 is spawned as an independent thread or process. May be used to setup a
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665 larger number of threads/processes doing the same thing. Each thread is
666 reported separately; to see statistics for all clones as a whole, use
667 :option:`group_reporting` in conjunction with :option:`new_group`.
a47b697c 668 See :option:`--max-jobs`. Default: 1.
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669
670
671Time related parameters
672~~~~~~~~~~~~~~~~~~~~~~~
673
674.. option:: runtime=time
675
f75ede1d 676 Tell fio to terminate processing after the specified period of time. It
f80dba8d 677 can be quite hard to determine for how long a specified job will run, so
f75ede1d 678 this parameter is handy to cap the total runtime to a given time. When
804c0839 679 the unit is omitted, the value is interpreted in seconds.
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680
681.. option:: time_based
682
683 If set, fio will run for the duration of the :option:`runtime` specified
684 even if the file(s) are completely read or written. It will simply loop over
685 the same workload as many times as the :option:`runtime` allows.
686
a881438b 687.. option:: startdelay=irange(time)
f80dba8d 688
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689 Delay the start of job for the specified amount of time. Can be a single
690 value or a range. When given as a range, each thread will choose a value
691 randomly from within the range. Value is in seconds if a unit is omitted.
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692
693.. option:: ramp_time=time
694
695 If set, fio will run the specified workload for this amount of time before
696 logging any performance numbers. Useful for letting performance settle
697 before logging results, thus minimizing the runtime required for stable
698 results. Note that the ``ramp_time`` is considered lead in time for a job,
699 thus it will increase the total runtime if a special timeout or
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700 :option:`runtime` is specified. When the unit is omitted, the value is
701 given in seconds.
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702
703.. option:: clocksource=str
704
705 Use the given clocksource as the base of timing. The supported options are:
706
707 **gettimeofday**
708 :manpage:`gettimeofday(2)`
709
710 **clock_gettime**
711 :manpage:`clock_gettime(2)`
712
713 **cpu**
714 Internal CPU clock source
715
716 cpu is the preferred clocksource if it is reliable, as it is very fast (and
717 fio is heavy on time calls). Fio will automatically use this clocksource if
718 it's supported and considered reliable on the system it is running on,
719 unless another clocksource is specifically set. For x86/x86-64 CPUs, this
720 means supporting TSC Invariant.
721
722.. option:: gtod_reduce=bool
723
724 Enable all of the :manpage:`gettimeofday(2)` reducing options
f75ede1d 725 (:option:`disable_clat`, :option:`disable_slat`, :option:`disable_bw_measurement`) plus
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726 reduce precision of the timeout somewhat to really shrink the
727 :manpage:`gettimeofday(2)` call count. With this option enabled, we only do
728 about 0.4% of the :manpage:`gettimeofday(2)` calls we would have done if all
729 time keeping was enabled.
730
731.. option:: gtod_cpu=int
732
733 Sometimes it's cheaper to dedicate a single thread of execution to just
734 getting the current time. Fio (and databases, for instance) are very
735 intensive on :manpage:`gettimeofday(2)` calls. With this option, you can set
736 one CPU aside for doing nothing but logging current time to a shared memory
737 location. Then the other threads/processes that run I/O workloads need only
738 copy that segment, instead of entering the kernel with a
739 :manpage:`gettimeofday(2)` call. The CPU set aside for doing these time
740 calls will be excluded from other uses. Fio will manually clear it from the
741 CPU mask of other jobs.
742
743
744Target file/device
745~~~~~~~~~~~~~~~~~~
746
747.. option:: directory=str
748
749 Prefix filenames with this directory. Used to place files in a different
750 location than :file:`./`. You can specify a number of directories by
751 separating the names with a ':' character. These directories will be
02dd2689 752 assigned equally distributed to job clones created by :option:`numjobs` as
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753 long as they are using generated filenames. If specific `filename(s)` are
754 set fio will use the first listed directory, and thereby matching the
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755 `filename` semantic (which generates a file for each clone if not
756 specified, but lets all clones use the same file if set).
f80dba8d 757
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758 See the :option:`filename` option for information on how to escape "``:``" and
759 "``\``" characters within the directory path itself.
f80dba8d 760
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761 Note: To control the directory fio will use for internal state files
762 use :option:`--aux-path`.
763
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764.. option:: filename=str
765
766 Fio normally makes up a `filename` based on the job name, thread number, and
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767 file number (see :option:`filename_format`). If you want to share files
768 between threads in a job or several
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769 jobs with fixed file paths, specify a `filename` for each of them to override
770 the default. If the ioengine is file based, you can specify a number of files
771 by separating the names with a ':' colon. So if you wanted a job to open
772 :file:`/dev/sda` and :file:`/dev/sdb` as the two working files, you would use
773 ``filename=/dev/sda:/dev/sdb``. This also means that whenever this option is
774 specified, :option:`nrfiles` is ignored. The size of regular files specified
02dd2689 775 by this option will be :option:`size` divided by number of files unless an
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776 explicit size is specified by :option:`filesize`.
777
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778 Each colon and backslash in the wanted path must be escaped with a ``\``
779 character. For instance, if the path is :file:`/dev/dsk/foo@3,0:c` then you
780 would use ``filename=/dev/dsk/foo@3,0\:c`` and if the path is
781 :file:`F:\\filename` then you would use ``filename=F\:\\filename``.
782
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783 On Windows, disk devices are accessed as :file:`\\\\.\\PhysicalDrive0` for
784 the first device, :file:`\\\\.\\PhysicalDrive1` for the second etc.
785 Note: Windows and FreeBSD prevent write access to areas
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786 of the disk containing in-use data (e.g. filesystems).
787
788 The filename "`-`" is a reserved name, meaning *stdin* or *stdout*. Which
789 of the two depends on the read/write direction set.
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790
791.. option:: filename_format=str
792
793 If sharing multiple files between jobs, it is usually necessary to have fio
794 generate the exact names that you want. By default, fio will name a file
795 based on the default file format specification of
796 :file:`jobname.jobnumber.filenumber`. With this option, that can be
797 customized. Fio will recognize and replace the following keywords in this
798 string:
799
800 **$jobname**
801 The name of the worker thread or process.
802 **$jobnum**
803 The incremental number of the worker thread or process.
804 **$filenum**
805 The incremental number of the file for that worker thread or
806 process.
807
808 To have dependent jobs share a set of files, this option can be set to have
809 fio generate filenames that are shared between the two. For instance, if
810 :file:`testfiles.$filenum` is specified, file number 4 for any job will be
811 named :file:`testfiles.4`. The default of :file:`$jobname.$jobnum.$filenum`
812 will be used if no other format specifier is given.
813
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814 If you specify a path then the directories will be created up to the
815 main directory for the file. So for example if you specify
816 ``filename_format=a/b/c/$jobnum`` then the directories a/b/c will be
817 created before the file setup part of the job. If you specify
818 :option:`directory` then the path will be relative that directory,
819 otherwise it is treated as the absolute path.
820
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821.. option:: unique_filename=bool
822
823 To avoid collisions between networked clients, fio defaults to prefixing any
824 generated filenames (with a directory specified) with the source of the
825 client connecting. To disable this behavior, set this option to 0.
826
827.. option:: opendir=str
828
829 Recursively open any files below directory `str`.
830
831.. option:: lockfile=str
832
833 Fio defaults to not locking any files before it does I/O to them. If a file
834 or file descriptor is shared, fio can serialize I/O to that file to make the
835 end result consistent. This is usual for emulating real workloads that share
836 files. The lock modes are:
837
838 **none**
839 No locking. The default.
840 **exclusive**
841 Only one thread or process may do I/O at a time, excluding all
842 others.
843 **readwrite**
844 Read-write locking on the file. Many readers may
845 access the file at the same time, but writes get exclusive access.
846
847.. option:: nrfiles=int
848
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849 Number of files to use for this job. Defaults to 1. The size of files
850 will be :option:`size` divided by this unless explicit size is specified by
851 :option:`filesize`. Files are created for each thread separately, and each
852 file will have a file number within its name by default, as explained in
853 :option:`filename` section.
854
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855
856.. option:: openfiles=int
857
858 Number of files to keep open at the same time. Defaults to the same as
859 :option:`nrfiles`, can be set smaller to limit the number simultaneous
860 opens.
861
862.. option:: file_service_type=str
863
864 Defines how fio decides which file from a job to service next. The following
865 types are defined:
866
867 **random**
868 Choose a file at random.
869
870 **roundrobin**
871 Round robin over opened files. This is the default.
872
873 **sequential**
874 Finish one file before moving on to the next. Multiple files can
f50fbdda 875 still be open depending on :option:`openfiles`.
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876
877 **zipf**
c60ebc45 878 Use a *Zipf* distribution to decide what file to access.
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879
880 **pareto**
c60ebc45 881 Use a *Pareto* distribution to decide what file to access.
f80dba8d 882
dd3503d3 883 **normal**
c60ebc45 884 Use a *Gaussian* (normal) distribution to decide what file to
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885 access.
886
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887 **gauss**
888 Alias for normal.
889
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890 For *random*, *roundrobin*, and *sequential*, a postfix can be appended to
891 tell fio how many I/Os to issue before switching to a new file. For example,
892 specifying ``file_service_type=random:8`` would cause fio to issue
893 8 I/Os before selecting a new file at random. For the non-uniform
894 distributions, a floating point postfix can be given to influence how the
895 distribution is skewed. See :option:`random_distribution` for a description
896 of how that would work.
897
898.. option:: ioscheduler=str
899
900 Attempt to switch the device hosting the file to the specified I/O scheduler
901 before running.
902
903.. option:: create_serialize=bool
904
905 If true, serialize the file creation for the jobs. This may be handy to
906 avoid interleaving of data files, which may greatly depend on the filesystem
a47b697c 907 used and even the number of processors in the system. Default: true.
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908
909.. option:: create_fsync=bool
910
22413915 911 :manpage:`fsync(2)` the data file after creation. This is the default.
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912
913.. option:: create_on_open=bool
914
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915 If true, don't pre-create files but allow the job's open() to create a file
916 when it's time to do I/O. Default: false -- pre-create all necessary files
917 when the job starts.
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918
919.. option:: create_only=bool
920
921 If true, fio will only run the setup phase of the job. If files need to be
4502cb42 922 laid out or updated on disk, only that will be done -- the actual job contents
a47b697c 923 are not executed. Default: false.
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924
925.. option:: allow_file_create=bool
926
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927 If true, fio is permitted to create files as part of its workload. If this
928 option is false, then fio will error out if
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929 the files it needs to use don't already exist. Default: true.
930
931.. option:: allow_mounted_write=bool
932
c60ebc45 933 If this isn't set, fio will abort jobs that are destructive (e.g. that write)
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934 to what appears to be a mounted device or partition. This should help catch
935 creating inadvertently destructive tests, not realizing that the test will
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936 destroy data on the mounted file system. Note that some platforms don't allow
937 writing against a mounted device regardless of this option. Default: false.
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938
939.. option:: pre_read=bool
940
941 If this is given, files will be pre-read into memory before starting the
942 given I/O operation. This will also clear the :option:`invalidate` flag,
943 since it is pointless to pre-read and then drop the cache. This will only
944 work for I/O engines that are seek-able, since they allow you to read the
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945 same data multiple times. Thus it will not work on non-seekable I/O engines
946 (e.g. network, splice). Default: false.
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947
948.. option:: unlink=bool
949
950 Unlink the job files when done. Not the default, as repeated runs of that
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951 job would then waste time recreating the file set again and again. Default:
952 false.
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953
954.. option:: unlink_each_loop=bool
955
a47b697c 956 Unlink job files after each iteration or loop. Default: false.
f80dba8d 957
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958.. option:: zonemode=str
959
960 Accepted values are:
961
962 **none**
963 The :option:`zonerange`, :option:`zonesize` and
964 :option:`zoneskip` parameters are ignored.
965 **strided**
966 I/O happens in a single zone until
967 :option:`zonesize` bytes have been transferred.
968 After that number of bytes has been
969 transferred processing of the next zone
970 starts.
971 **zbd**
972 Zoned block device mode. I/O happens
973 sequentially in each zone, even if random I/O
974 has been selected. Random I/O happens across
975 all zones instead of being restricted to a
976 single zone. The :option:`zoneskip` parameter
977 is ignored. :option:`zonerange` and
978 :option:`zonesize` must be identical.
979
5faddc64 980.. option:: zonerange=int
f80dba8d 981
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982 Size of a single zone. See also :option:`zonesize` and
983 :option:`zoneskip`.
f80dba8d 984
5faddc64 985.. option:: zonesize=int
f80dba8d 986
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987 For :option:`zonemode` =strided, this is the number of bytes to
988 transfer before skipping :option:`zoneskip` bytes. If this parameter
989 is smaller than :option:`zonerange` then only a fraction of each zone
990 with :option:`zonerange` bytes will be accessed. If this parameter is
991 larger than :option:`zonerange` then each zone will be accessed
992 multiple times before skipping to the next zone.
993
994 For :option:`zonemode` =zbd, this is the size of a single zone. The
995 :option:`zonerange` parameter is ignored in this mode.
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996
997.. option:: zoneskip=int
998
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999 For :option:`zonemode` =strided, the number of bytes to skip after
1000 :option:`zonesize` bytes of data have been transferred. This parameter
1001 must be zero for :option:`zonemode` =zbd.
f80dba8d 1002
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1003.. option:: read_beyond_wp=bool
1004
1005 This parameter applies to :option:`zonemode` =zbd only.
1006
1007 Zoned block devices are block devices that consist of multiple zones.
1008 Each zone has a type, e.g. conventional or sequential. A conventional
1009 zone can be written at any offset that is a multiple of the block
1010 size. Sequential zones must be written sequentially. The position at
1011 which a write must occur is called the write pointer. A zoned block
1012 device can be either drive managed, host managed or host aware. For
1013 host managed devices the host must ensure that writes happen
1014 sequentially. Fio recognizes host managed devices and serializes
1015 writes to sequential zones for these devices.
1016
1017 If a read occurs in a sequential zone beyond the write pointer then
1018 the zoned block device will complete the read without reading any data
1019 from the storage medium. Since such reads lead to unrealistically high
1020 bandwidth and IOPS numbers fio only reads beyond the write pointer if
1021 explicitly told to do so. Default: false.
1022
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1023.. option:: max_open_zones=int
1024
1025 When running a random write test across an entire drive many more
1026 zones will be open than in a typical application workload. Hence this
1027 command line option that allows to limit the number of open zones. The
1028 number of open zones is defined as the number of zones to which write
1029 commands are issued.
1030
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1031.. option:: zone_reset_threshold=float
1032
1033 A number between zero and one that indicates the ratio of logical
1034 blocks with data to the total number of logical blocks in the test
1035 above which zones should be reset periodically.
1036
1037.. option:: zone_reset_frequency=float
1038
1039 A number between zero and one that indicates how often a zone reset
1040 should be issued if the zone reset threshold has been exceeded. A zone
1041 reset is submitted after each (1 / zone_reset_frequency) write
1042 requests. This and the previous parameter can be used to simulate
1043 garbage collection activity.
1044
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1045
1046I/O type
1047~~~~~~~~
1048
1049.. option:: direct=bool
1050
1051 If value is true, use non-buffered I/O. This is usually O_DIRECT. Note that
8e889110 1052 OpenBSD and ZFS on Solaris don't support direct I/O. On Windows the synchronous
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1053 ioengines don't support direct I/O. Default: false.
1054
1055.. option:: atomic=bool
1056
1057 If value is true, attempt to use atomic direct I/O. Atomic writes are
1058 guaranteed to be stable once acknowledged by the operating system. Only
1059 Linux supports O_ATOMIC right now.
1060
1061.. option:: buffered=bool
1062
1063 If value is true, use buffered I/O. This is the opposite of the
1064 :option:`direct` option. Defaults to true.
1065
1066.. option:: readwrite=str, rw=str
1067
1068 Type of I/O pattern. Accepted values are:
1069
1070 **read**
1071 Sequential reads.
1072 **write**
1073 Sequential writes.
1074 **trim**
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1075 Sequential trims (Linux block devices and SCSI
1076 character devices only).
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1077 **randread**
1078 Random reads.
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1079 **randwrite**
1080 Random writes.
f80dba8d 1081 **randtrim**
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1082 Random trims (Linux block devices and SCSI
1083 character devices only).
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1084 **rw,readwrite**
1085 Sequential mixed reads and writes.
1086 **randrw**
1087 Random mixed reads and writes.
1088 **trimwrite**
1089 Sequential trim+write sequences. Blocks will be trimmed first,
1090 then the same blocks will be written to.
1091
1092 Fio defaults to read if the option is not specified. For the mixed I/O
1093 types, the default is to split them 50/50. For certain types of I/O the
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1094 result may still be skewed a bit, since the speed may be different.
1095
1096 It is possible to specify the number of I/Os to do before getting a new
1097 offset by appending ``:<nr>`` to the end of the string given. For a
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1098 random read, it would look like ``rw=randread:8`` for passing in an offset
1099 modifier with a value of 8. If the suffix is used with a sequential I/O
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1100 pattern, then the *<nr>* value specified will be **added** to the generated
1101 offset for each I/O turning sequential I/O into sequential I/O with holes.
1102 For instance, using ``rw=write:4k`` will skip 4k for every write. Also see
1103 the :option:`rw_sequencer` option.
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1104
1105.. option:: rw_sequencer=str
1106
1107 If an offset modifier is given by appending a number to the ``rw=<str>``
1108 line, then this option controls how that number modifies the I/O offset
1109 being generated. Accepted values are:
1110
1111 **sequential**
1112 Generate sequential offset.
1113 **identical**
1114 Generate the same offset.
1115
1116 ``sequential`` is only useful for random I/O, where fio would normally
c60ebc45 1117 generate a new random offset for every I/O. If you append e.g. 8 to randread,
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1118 you would get a new random offset for every 8 I/Os. The result would be a
1119 seek for only every 8 I/Os, instead of for every I/O. Use ``rw=randread:8``
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1120 to specify that. As sequential I/O is already sequential, setting
1121 ``sequential`` for that would not result in any differences. ``identical``
1122 behaves in a similar fashion, except it sends the same offset 8 number of
1123 times before generating a new offset.
1124
1125.. option:: unified_rw_reporting=bool
1126
1127 Fio normally reports statistics on a per data direction basis, meaning that
1128 reads, writes, and trims are accounted and reported separately. If this
1129 option is set fio sums the results and report them as "mixed" instead.
1130
1131.. option:: randrepeat=bool
1132
1133 Seed the random number generator used for random I/O patterns in a
1134 predictable way so the pattern is repeatable across runs. Default: true.
1135
1136.. option:: allrandrepeat=bool
1137
1138 Seed all random number generators in a predictable way so results are
1139 repeatable across runs. Default: false.
1140
1141.. option:: randseed=int
1142
1143 Seed the random number generators based on this seed value, to be able to
1144 control what sequence of output is being generated. If not set, the random
1145 sequence depends on the :option:`randrepeat` setting.
1146
1147.. option:: fallocate=str
1148
1149 Whether pre-allocation is performed when laying down files.
1150 Accepted values are:
1151
1152 **none**
1153 Do not pre-allocate space.
1154
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1155 **native**
1156 Use a platform's native pre-allocation call but fall back to
1157 **none** behavior if it fails/is not implemented.
1158
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1159 **posix**
1160 Pre-allocate via :manpage:`posix_fallocate(3)`.
1161
1162 **keep**
1163 Pre-allocate via :manpage:`fallocate(2)` with
1164 FALLOC_FL_KEEP_SIZE set.
1165
1166 **0**
1167 Backward-compatible alias for **none**.
1168
1169 **1**
1170 Backward-compatible alias for **posix**.
1171
1172 May not be available on all supported platforms. **keep** is only available
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1173 on Linux. If using ZFS on Solaris this cannot be set to **posix**
1174 because ZFS doesn't support pre-allocation. Default: **native** if any
1175 pre-allocation methods are available, **none** if not.
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1176
1177.. option:: fadvise_hint=str
1178
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1179 Use :manpage:`posix_fadvise(2)` or :manpage:`posix_fadvise(2)` to
1180 advise the kernel on what I/O patterns are likely to be issued.
1181 Accepted values are:
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1182
1183 **0**
1184 Backwards-compatible hint for "no hint".
1185
1186 **1**
1187 Backwards compatible hint for "advise with fio workload type". This
1188 uses **FADV_RANDOM** for a random workload, and **FADV_SEQUENTIAL**
1189 for a sequential workload.
1190
1191 **sequential**
1192 Advise using **FADV_SEQUENTIAL**.
1193
1194 **random**
1195 Advise using **FADV_RANDOM**.
1196
8f4b9f24 1197.. option:: write_hint=str
f80dba8d 1198
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1199 Use :manpage:`fcntl(2)` to advise the kernel what life time to expect
1200 from a write. Only supported on Linux, as of version 4.13. Accepted
1201 values are:
1202
1203 **none**
1204 No particular life time associated with this file.
1205
1206 **short**
1207 Data written to this file has a short life time.
1208
1209 **medium**
1210 Data written to this file has a medium life time.
1211
1212 **long**
1213 Data written to this file has a long life time.
1214
1215 **extreme**
1216 Data written to this file has a very long life time.
1217
1218 The values are all relative to each other, and no absolute meaning
1219 should be associated with them.
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1220
1221.. option:: offset=int
1222
82dbb8cb 1223 Start I/O at the provided offset in the file, given as either a fixed size in
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1224 bytes or a percentage. If a percentage is given, the generated offset will be
1225 aligned to the minimum ``blocksize`` or to the value of ``offset_align`` if
1226 provided. Data before the given offset will not be touched. This
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BW
1227 effectively caps the file size at `real_size - offset`. Can be combined with
1228 :option:`size` to constrain the start and end range of the I/O workload.
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1229 A percentage can be specified by a number between 1 and 100 followed by '%',
1230 for example, ``offset=20%`` to specify 20%.
f80dba8d 1231
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1232.. option:: offset_align=int
1233
1234 If set to non-zero value, the byte offset generated by a percentage ``offset``
1235 is aligned upwards to this value. Defaults to 0 meaning that a percentage
1236 offset is aligned to the minimum block size.
1237
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1238.. option:: offset_increment=int
1239
1240 If this is provided, then the real offset becomes `offset + offset_increment
1241 * thread_number`, where the thread number is a counter that starts at 0 and
1242 is incremented for each sub-job (i.e. when :option:`numjobs` option is
1243 specified). This option is useful if there are several jobs which are
1244 intended to operate on a file in parallel disjoint segments, with even
1245 spacing between the starting points.
1246
1247.. option:: number_ios=int
1248
c60ebc45 1249 Fio will normally perform I/Os until it has exhausted the size of the region
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1250 set by :option:`size`, or if it exhaust the allocated time (or hits an error
1251 condition). With this setting, the range/size can be set independently of
c60ebc45 1252 the number of I/Os to perform. When fio reaches this number, it will exit
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1253 normally and report status. Note that this does not extend the amount of I/O
1254 that will be done, it will only stop fio if this condition is met before
1255 other end-of-job criteria.
1256
1257.. option:: fsync=int
1258
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1259 If writing to a file, issue an :manpage:`fsync(2)` (or its equivalent) of
1260 the dirty data for every number of blocks given. For example, if you give 32
1261 as a parameter, fio will sync the file after every 32 writes issued. If fio is
1262 using non-buffered I/O, we may not sync the file. The exception is the sg
1263 I/O engine, which synchronizes the disk cache anyway. Defaults to 0, which
1264 means fio does not periodically issue and wait for a sync to complete. Also
1265 see :option:`end_fsync` and :option:`fsync_on_close`.
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1266
1267.. option:: fdatasync=int
1268
1269 Like :option:`fsync` but uses :manpage:`fdatasync(2)` to only sync data and
000a5f1c 1270 not metadata blocks. In Windows, FreeBSD, and DragonFlyBSD there is no
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1271 :manpage:`fdatasync(2)` so this falls back to using :manpage:`fsync(2)`.
1272 Defaults to 0, which means fio does not periodically issue and wait for a
1273 data-only sync to complete.
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1274
1275.. option:: write_barrier=int
1276
2831be97 1277 Make every `N-th` write a barrier write.
f80dba8d 1278
f50fbdda 1279.. option:: sync_file_range=str:int
f80dba8d 1280
f50fbdda 1281 Use :manpage:`sync_file_range(2)` for every `int` number of write
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1282 operations. Fio will track range of writes that have happened since the last
1283 :manpage:`sync_file_range(2)` call. `str` can currently be one or more of:
1284
1285 **wait_before**
1286 SYNC_FILE_RANGE_WAIT_BEFORE
1287 **write**
1288 SYNC_FILE_RANGE_WRITE
1289 **wait_after**
1290 SYNC_FILE_RANGE_WAIT_AFTER
1291
1292 So if you do ``sync_file_range=wait_before,write:8``, fio would use
1293 ``SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE`` for every 8
1294 writes. Also see the :manpage:`sync_file_range(2)` man page. This option is
1295 Linux specific.
1296
1297.. option:: overwrite=bool
1298
1299 If true, writes to a file will always overwrite existing data. If the file
1300 doesn't already exist, it will be created before the write phase begins. If
1301 the file exists and is large enough for the specified write phase, nothing
a47b697c 1302 will be done. Default: false.
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1303
1304.. option:: end_fsync=bool
1305
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1306 If true, :manpage:`fsync(2)` file contents when a write stage has completed.
1307 Default: false.
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1308
1309.. option:: fsync_on_close=bool
1310
1311 If true, fio will :manpage:`fsync(2)` a dirty file on close. This differs
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1312 from :option:`end_fsync` in that it will happen on every file close, not
1313 just at the end of the job. Default: false.
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1314
1315.. option:: rwmixread=int
1316
1317 Percentage of a mixed workload that should be reads. Default: 50.
1318
1319.. option:: rwmixwrite=int
1320
1321 Percentage of a mixed workload that should be writes. If both
1322 :option:`rwmixread` and :option:`rwmixwrite` is given and the values do not
1323 add up to 100%, the latter of the two will be used to override the
1324 first. This may interfere with a given rate setting, if fio is asked to
1325 limit reads or writes to a certain rate. If that is the case, then the
1326 distribution may be skewed. Default: 50.
1327
1328.. option:: random_distribution=str:float[,str:float][,str:float]
1329
1330 By default, fio will use a completely uniform random distribution when asked
1331 to perform random I/O. Sometimes it is useful to skew the distribution in
1332 specific ways, ensuring that some parts of the data is more hot than others.
1333 fio includes the following distribution models:
1334
1335 **random**
1336 Uniform random distribution
1337
1338 **zipf**
1339 Zipf distribution
1340
1341 **pareto**
1342 Pareto distribution
1343
b2f4b559 1344 **normal**
c60ebc45 1345 Normal (Gaussian) distribution
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1346
1347 **zoned**
1348 Zoned random distribution
1349
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1350 **zoned_abs**
1351 Zone absolute random distribution
1352
f80dba8d 1353 When using a **zipf** or **pareto** distribution, an input value is also
f50fbdda 1354 needed to define the access pattern. For **zipf**, this is the `Zipf
c60ebc45 1355 theta`. For **pareto**, it's the `Pareto power`. Fio includes a test
f50fbdda 1356 program, :command:`fio-genzipf`, that can be used visualize what the given input
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1357 values will yield in terms of hit rates. If you wanted to use **zipf** with
1358 a `theta` of 1.2, you would use ``random_distribution=zipf:1.2`` as the
1359 option. If a non-uniform model is used, fio will disable use of the random
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1360 map. For the **normal** distribution, a normal (Gaussian) deviation is
1361 supplied as a value between 0 and 100.
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1362
1363 For a **zoned** distribution, fio supports specifying percentages of I/O
1364 access that should fall within what range of the file or device. For
1365 example, given a criteria of:
1366
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1367 * 60% of accesses should be to the first 10%
1368 * 30% of accesses should be to the next 20%
1369 * 8% of accesses should be to the next 30%
1370 * 2% of accesses should be to the next 40%
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1371
1372 we can define that through zoning of the random accesses. For the above
1373 example, the user would do::
1374
1375 random_distribution=zoned:60/10:30/20:8/30:2/40
1376
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1377 A **zoned_abs** distribution works exactly like the **zoned**, except
1378 that it takes absolute sizes. For example, let's say you wanted to
1379 define access according to the following criteria:
1380
1381 * 60% of accesses should be to the first 20G
1382 * 30% of accesses should be to the next 100G
1383 * 10% of accesses should be to the next 500G
1384
1385 we can define an absolute zoning distribution with:
1386
1387 random_distribution=zoned_abs=60/20G:30/100G:10/500g
1388
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1389 For both **zoned** and **zoned_abs**, fio supports defining up to
1390 256 separate zones.
1391
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1392 Similarly to how :option:`bssplit` works for setting ranges and
1393 percentages of block sizes. Like :option:`bssplit`, it's possible to
1394 specify separate zones for reads, writes, and trims. If just one set
1395 is given, it'll apply to all of them. This goes for both **zoned**
1396 **zoned_abs** distributions.
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1397
1398.. option:: percentage_random=int[,int][,int]
1399
1400 For a random workload, set how big a percentage should be random. This
1401 defaults to 100%, in which case the workload is fully random. It can be set
1402 from anywhere from 0 to 100. Setting it to 0 would make the workload fully
1403 sequential. Any setting in between will result in a random mix of sequential
1404 and random I/O, at the given percentages. Comma-separated values may be
1405 specified for reads, writes, and trims as described in :option:`blocksize`.
1406
1407.. option:: norandommap
1408
1409 Normally fio will cover every block of the file when doing random I/O. If
1410 this option is given, fio will just get a new random offset without looking
1411 at past I/O history. This means that some blocks may not be read or written,
1412 and that some blocks may be read/written more than once. If this option is
1413 used with :option:`verify` and multiple blocksizes (via :option:`bsrange`),
1414 only intact blocks are verified, i.e., partially-overwritten blocks are
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1415 ignored. With an async I/O engine and an I/O depth > 1, it is possible for
1416 the same block to be overwritten, which can cause verification errors. Either
1417 do not use norandommap in this case, or also use the lfsr random generator.
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1418
1419.. option:: softrandommap=bool
1420
1421 See :option:`norandommap`. If fio runs with the random block map enabled and
1422 it fails to allocate the map, if this option is set it will continue without
1423 a random block map. As coverage will not be as complete as with random maps,
1424 this option is disabled by default.
1425
1426.. option:: random_generator=str
1427
f50fbdda 1428 Fio supports the following engines for generating I/O offsets for random I/O:
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1429
1430 **tausworthe**
f50fbdda 1431 Strong 2^88 cycle random number generator.
f80dba8d 1432 **lfsr**
f50fbdda 1433 Linear feedback shift register generator.
f80dba8d 1434 **tausworthe64**
f50fbdda 1435 Strong 64-bit 2^258 cycle random number generator.
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1436
1437 **tausworthe** is a strong random number generator, but it requires tracking
1438 on the side if we want to ensure that blocks are only read or written
f50fbdda 1439 once. **lfsr** guarantees that we never generate the same offset twice, and
f80dba8d 1440 it's also less computationally expensive. It's not a true random generator,
f50fbdda 1441 however, though for I/O purposes it's typically good enough. **lfsr** only
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1442 works with single block sizes, not with workloads that use multiple block
1443 sizes. If used with such a workload, fio may read or write some blocks
1444 multiple times. The default value is **tausworthe**, unless the required
1445 space exceeds 2^32 blocks. If it does, then **tausworthe64** is
1446 selected automatically.
1447
1448
1449Block size
1450~~~~~~~~~~
1451
1452.. option:: blocksize=int[,int][,int], bs=int[,int][,int]
1453
1454 The block size in bytes used for I/O units. Default: 4096. A single value
1455 applies to reads, writes, and trims. Comma-separated values may be
1456 specified for reads, writes, and trims. A value not terminated in a comma
1457 applies to subsequent types.
1458
1459 Examples:
1460
1461 **bs=256k**
1462 means 256k for reads, writes and trims.
1463
1464 **bs=8k,32k**
1465 means 8k for reads, 32k for writes and trims.
1466
1467 **bs=8k,32k,**
1468 means 8k for reads, 32k for writes, and default for trims.
1469
1470 **bs=,8k**
1471 means default for reads, 8k for writes and trims.
1472
1473 **bs=,8k,**
b443ae44 1474 means default for reads, 8k for writes, and default for trims.
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1475
1476.. option:: blocksize_range=irange[,irange][,irange], bsrange=irange[,irange][,irange]
1477
1478 A range of block sizes in bytes for I/O units. The issued I/O unit will
1479 always be a multiple of the minimum size, unless
1480 :option:`blocksize_unaligned` is set.
1481
1482 Comma-separated ranges may be specified for reads, writes, and trims as
1483 described in :option:`blocksize`.
1484
1485 Example: ``bsrange=1k-4k,2k-8k``.
1486
1487.. option:: bssplit=str[,str][,str]
1488
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1489 Sometimes you want even finer grained control of the block sizes
1490 issued, not just an even split between them. This option allows you to
1491 weight various block sizes, so that you are able to define a specific
1492 amount of block sizes issued. The format for this option is::
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1493
1494 bssplit=blocksize/percentage:blocksize/percentage
1495
6a16ece8
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1496 for as many block sizes as needed. So if you want to define a workload
1497 that has 50% 64k blocks, 10% 4k blocks, and 40% 32k blocks, you would
1498 write::
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1499
1500 bssplit=4k/10:64k/50:32k/40
1501
6a16ece8
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1502 Ordering does not matter. If the percentage is left blank, fio will
1503 fill in the remaining values evenly. So a bssplit option like this one::
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1504
1505 bssplit=4k/50:1k/:32k/
1506
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1507 would have 50% 4k ios, and 25% 1k and 32k ios. The percentages always
1508 add up to 100, if bssplit is given a range that adds up to more, it
1509 will error out.
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1510
1511 Comma-separated values may be specified for reads, writes, and trims as
1512 described in :option:`blocksize`.
1513
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1514 If you want a workload that has 50% 2k reads and 50% 4k reads, while
1515 having 90% 4k writes and 10% 8k writes, you would specify::
f80dba8d 1516
cf04b906 1517 bssplit=2k/50:4k/50,4k/90:8k/10
f80dba8d 1518
6a16ece8
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1519 Fio supports defining up to 64 different weights for each data
1520 direction.
1521
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1522.. option:: blocksize_unaligned, bs_unaligned
1523
1524 If set, fio will issue I/O units with any size within
1525 :option:`blocksize_range`, not just multiples of the minimum size. This
1526 typically won't work with direct I/O, as that normally requires sector
1527 alignment.
1528
589e88b7 1529.. option:: bs_is_seq_rand=bool
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1530
1531 If this option is set, fio will use the normal read,write blocksize settings
1532 as sequential,random blocksize settings instead. Any random read or write
1533 will use the WRITE blocksize settings, and any sequential read or write will
1534 use the READ blocksize settings.
1535
1536.. option:: blockalign=int[,int][,int], ba=int[,int][,int]
1537
1538 Boundary to which fio will align random I/O units. Default:
1539 :option:`blocksize`. Minimum alignment is typically 512b for using direct
1540 I/O, though it usually depends on the hardware block size. This option is
1541 mutually exclusive with using a random map for files, so it will turn off
1542 that option. Comma-separated values may be specified for reads, writes, and
1543 trims as described in :option:`blocksize`.
1544
1545
1546Buffers and memory
1547~~~~~~~~~~~~~~~~~~
1548
1549.. option:: zero_buffers
1550
1551 Initialize buffers with all zeros. Default: fill buffers with random data.
1552
1553.. option:: refill_buffers
1554
1555 If this option is given, fio will refill the I/O buffers on every
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1556 submit. Only makes sense if :option:`zero_buffers` isn't specified,
1557 naturally. Defaults to being unset i.e., the buffer is only filled at
1558 init time and the data in it is reused when possible but if any of
1559 :option:`verify`, :option:`buffer_compress_percentage` or
1560 :option:`dedupe_percentage` are enabled then `refill_buffers` is also
1561 automatically enabled.
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1562
1563.. option:: scramble_buffers=bool
1564
1565 If :option:`refill_buffers` is too costly and the target is using data
1566 deduplication, then setting this option will slightly modify the I/O buffer
1567 contents to defeat normal de-dupe attempts. This is not enough to defeat
1568 more clever block compression attempts, but it will stop naive dedupe of
1569 blocks. Default: true.
1570
1571.. option:: buffer_compress_percentage=int
1572
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1573 If this is set, then fio will attempt to provide I/O buffer content
1574 (on WRITEs) that compresses to the specified level. Fio does this by
1575 providing a mix of random data followed by fixed pattern data. The
1576 fixed pattern is either zeros, or the pattern specified by
1577 :option:`buffer_pattern`. If the `buffer_pattern` option is used, it
1578 might skew the compression ratio slightly. Setting
1579 `buffer_compress_percentage` to a value other than 100 will also
1580 enable :option:`refill_buffers` in order to reduce the likelihood that
1581 adjacent blocks are so similar that they over compress when seen
1582 together. See :option:`buffer_compress_chunk` for how to set a finer or
1583 coarser granularity for the random/fixed data region. Defaults to unset
1584 i.e., buffer data will not adhere to any compression level.
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1585
1586.. option:: buffer_compress_chunk=int
1587
72592780
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1588 This setting allows fio to manage how big the random/fixed data region
1589 is when using :option:`buffer_compress_percentage`. When
1590 `buffer_compress_chunk` is set to some non-zero value smaller than the
1591 block size, fio can repeat the random/fixed region throughout the I/O
1592 buffer at the specified interval (which particularly useful when
1593 bigger block sizes are used for a job). When set to 0, fio will use a
1594 chunk size that matches the block size resulting in a single
1595 random/fixed region within the I/O buffer. Defaults to 512. When the
1596 unit is omitted, the value is interpreted in bytes.
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1597
1598.. option:: buffer_pattern=str
1599
a1554f65
SB
1600 If set, fio will fill the I/O buffers with this pattern or with the contents
1601 of a file. If not set, the contents of I/O buffers are defined by the other
1602 options related to buffer contents. The setting can be any pattern of bytes,
1603 and can be prefixed with 0x for hex values. It may also be a string, where
1604 the string must then be wrapped with ``""``. Or it may also be a filename,
1605 where the filename must be wrapped with ``''`` in which case the file is
1606 opened and read. Note that not all the file contents will be read if that
1607 would cause the buffers to overflow. So, for example::
1608
1609 buffer_pattern='filename'
1610
1611 or::
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1612
1613 buffer_pattern="abcd"
1614
1615 or::
1616
1617 buffer_pattern=-12
1618
1619 or::
1620
1621 buffer_pattern=0xdeadface
1622
1623 Also you can combine everything together in any order::
1624
a1554f65 1625 buffer_pattern=0xdeadface"abcd"-12'filename'
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1626
1627.. option:: dedupe_percentage=int
1628
1629 If set, fio will generate this percentage of identical buffers when
1630 writing. These buffers will be naturally dedupable. The contents of the
1631 buffers depend on what other buffer compression settings have been set. It's
1632 possible to have the individual buffers either fully compressible, or not at
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1633 all -- this option only controls the distribution of unique buffers. Setting
1634 this option will also enable :option:`refill_buffers` to prevent every buffer
1635 being identical.
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1636
1637.. option:: invalidate=bool
1638
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1639 Invalidate the buffer/page cache parts of the files to be used prior to
1640 starting I/O if the platform and file type support it. Defaults to true.
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1641 This will be ignored if :option:`pre_read` is also specified for the
1642 same job.
f80dba8d
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1643
1644.. option:: sync=bool
1645
1646 Use synchronous I/O for buffered writes. For the majority of I/O engines,
1647 this means using O_SYNC. Default: false.
1648
1649.. option:: iomem=str, mem=str
1650
1651 Fio can use various types of memory as the I/O unit buffer. The allowed
1652 values are:
1653
1654 **malloc**
1655 Use memory from :manpage:`malloc(3)` as the buffers. Default memory
1656 type.
1657
1658 **shm**
1659 Use shared memory as the buffers. Allocated through
1660 :manpage:`shmget(2)`.
1661
1662 **shmhuge**
1663 Same as shm, but use huge pages as backing.
1664
1665 **mmap**
22413915 1666 Use :manpage:`mmap(2)` to allocate buffers. May either be anonymous memory, or can
f80dba8d
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1667 be file backed if a filename is given after the option. The format
1668 is `mem=mmap:/path/to/file`.
1669
1670 **mmaphuge**
1671 Use a memory mapped huge file as the buffer backing. Append filename
1672 after mmaphuge, ala `mem=mmaphuge:/hugetlbfs/file`.
1673
1674 **mmapshared**
1675 Same as mmap, but use a MMAP_SHARED mapping.
1676
03553853
YR
1677 **cudamalloc**
1678 Use GPU memory as the buffers for GPUDirect RDMA benchmark.
f50fbdda 1679 The :option:`ioengine` must be `rdma`.
03553853 1680
f80dba8d
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1681 The area allocated is a function of the maximum allowed bs size for the job,
1682 multiplied by the I/O depth given. Note that for **shmhuge** and
1683 **mmaphuge** to work, the system must have free huge pages allocated. This
1684 can normally be checked and set by reading/writing
1685 :file:`/proc/sys/vm/nr_hugepages` on a Linux system. Fio assumes a huge page
1686 is 4MiB in size. So to calculate the number of huge pages you need for a
1687 given job file, add up the I/O depth of all jobs (normally one unless
1688 :option:`iodepth` is used) and multiply by the maximum bs set. Then divide
1689 that number by the huge page size. You can see the size of the huge pages in
1690 :file:`/proc/meminfo`. If no huge pages are allocated by having a non-zero
1691 number in `nr_hugepages`, using **mmaphuge** or **shmhuge** will fail. Also
1692 see :option:`hugepage-size`.
1693
1694 **mmaphuge** also needs to have hugetlbfs mounted and the file location
1695 should point there. So if it's mounted in :file:`/huge`, you would use
1696 `mem=mmaphuge:/huge/somefile`.
1697
f50fbdda 1698.. option:: iomem_align=int, mem_align=int
f80dba8d
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1699
1700 This indicates the memory alignment of the I/O memory buffers. Note that
1701 the given alignment is applied to the first I/O unit buffer, if using
1702 :option:`iodepth` the alignment of the following buffers are given by the
1703 :option:`bs` used. In other words, if using a :option:`bs` that is a
1704 multiple of the page sized in the system, all buffers will be aligned to
1705 this value. If using a :option:`bs` that is not page aligned, the alignment
1706 of subsequent I/O memory buffers is the sum of the :option:`iomem_align` and
1707 :option:`bs` used.
1708
1709.. option:: hugepage-size=int
1710
1711 Defines the size of a huge page. Must at least be equal to the system
1712 setting, see :file:`/proc/meminfo`. Defaults to 4MiB. Should probably
1713 always be a multiple of megabytes, so using ``hugepage-size=Xm`` is the
1714 preferred way to set this to avoid setting a non-pow-2 bad value.
1715
1716.. option:: lockmem=int
1717
1718 Pin the specified amount of memory with :manpage:`mlock(2)`. Can be used to
1719 simulate a smaller amount of memory. The amount specified is per worker.
1720
1721
1722I/O size
1723~~~~~~~~
1724
1725.. option:: size=int
1726
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1727 The total size of file I/O for each thread of this job. Fio will run until
1728 this many bytes has been transferred, unless runtime is limited by other options
1729 (such as :option:`runtime`, for instance, or increased/decreased by :option:`io_size`).
1730 Fio will divide this size between the available files determined by options
1731 such as :option:`nrfiles`, :option:`filename`, unless :option:`filesize` is
1732 specified by the job. If the result of division happens to be 0, the size is
c4aa2d08 1733 set to the physical size of the given files or devices if they exist.
79591fa9 1734 If this option is not specified, fio will use the full size of the given
f80dba8d
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1735 files or devices. If the files do not exist, size must be given. It is also
1736 possible to give size as a percentage between 1 and 100. If ``size=20%`` is
1737 given, fio will use 20% of the full size of the given files or devices.
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1738 Can be combined with :option:`offset` to constrain the start and end range
1739 that I/O will be done within.
f80dba8d
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1740
1741.. option:: io_size=int, io_limit=int
1742
1743 Normally fio operates within the region set by :option:`size`, which means
1744 that the :option:`size` option sets both the region and size of I/O to be
1745 performed. Sometimes that is not what you want. With this option, it is
1746 possible to define just the amount of I/O that fio should do. For instance,
1747 if :option:`size` is set to 20GiB and :option:`io_size` is set to 5GiB, fio
1748 will perform I/O within the first 20GiB but exit when 5GiB have been
1749 done. The opposite is also possible -- if :option:`size` is set to 20GiB,
1750 and :option:`io_size` is set to 40GiB, then fio will do 40GiB of I/O within
1751 the 0..20GiB region.
1752
7fdd97ca 1753.. option:: filesize=irange(int)
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1754
1755 Individual file sizes. May be a range, in which case fio will select sizes
1756 for files at random within the given range and limited to :option:`size` in
1757 total (if that is given). If not given, each created file is the same size.
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1758 This option overrides :option:`size` in terms of file size, which means
1759 this value is used as a fixed size or possible range of each file.
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1760
1761.. option:: file_append=bool
1762
1763 Perform I/O after the end of the file. Normally fio will operate within the
1764 size of a file. If this option is set, then fio will append to the file
1765 instead. This has identical behavior to setting :option:`offset` to the size
1766 of a file. This option is ignored on non-regular files.
1767
1768.. option:: fill_device=bool, fill_fs=bool
1769
1770 Sets size to something really large and waits for ENOSPC (no space left on
1771 device) as the terminating condition. Only makes sense with sequential
1772 write. For a read workload, the mount point will be filled first then I/O
1773 started on the result. This option doesn't make sense if operating on a raw
1774 device node, since the size of that is already known by the file system.
1775 Additionally, writing beyond end-of-device will not return ENOSPC there.
1776
1777
1778I/O engine
1779~~~~~~~~~~
1780
1781.. option:: ioengine=str
1782
1783 Defines how the job issues I/O to the file. The following types are defined:
1784
1785 **sync**
1786 Basic :manpage:`read(2)` or :manpage:`write(2)`
1787 I/O. :manpage:`lseek(2)` is used to position the I/O location.
54227e6b 1788 See :option:`fsync` and :option:`fdatasync` for syncing write I/Os.
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1789
1790 **psync**
1791 Basic :manpage:`pread(2)` or :manpage:`pwrite(2)` I/O. Default on
1792 all supported operating systems except for Windows.
1793
1794 **vsync**
1795 Basic :manpage:`readv(2)` or :manpage:`writev(2)` I/O. Will emulate
c60ebc45 1796 queuing by coalescing adjacent I/Os into a single submission.
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1797
1798 **pvsync**
1799 Basic :manpage:`preadv(2)` or :manpage:`pwritev(2)` I/O.
1800
1801 **pvsync2**
1802 Basic :manpage:`preadv2(2)` or :manpage:`pwritev2(2)` I/O.
1803
1804 **libaio**
1805 Linux native asynchronous I/O. Note that Linux may only support
22413915 1806 queued behavior with non-buffered I/O (set ``direct=1`` or
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1807 ``buffered=0``).
1808 This engine defines engine specific options.
1809
1810 **posixaio**
1811 POSIX asynchronous I/O using :manpage:`aio_read(3)` and
1812 :manpage:`aio_write(3)`.
1813
1814 **solarisaio**
1815 Solaris native asynchronous I/O.
1816
1817 **windowsaio**
1818 Windows native asynchronous I/O. Default on Windows.
1819
1820 **mmap**
1821 File is memory mapped with :manpage:`mmap(2)` and data copied
1822 to/from using :manpage:`memcpy(3)`.
1823
1824 **splice**
1825 :manpage:`splice(2)` is used to transfer the data and
1826 :manpage:`vmsplice(2)` to transfer data from user space to the
1827 kernel.
1828
1829 **sg**
1830 SCSI generic sg v3 I/O. May either be synchronous using the SG_IO
1831 ioctl, or if the target is an sg character device we use
1832 :manpage:`read(2)` and :manpage:`write(2)` for asynchronous
f50fbdda 1833 I/O. Requires :option:`filename` option to specify either block or
3740cfc8 1834 character devices. This engine supports trim operations.
52b81b7c 1835 The sg engine includes engine specific options.
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1836
1837 **null**
1838 Doesn't transfer any data, just pretends to. This is mainly used to
1839 exercise fio itself and for debugging/testing purposes.
1840
1841 **net**
1842 Transfer over the network to given ``host:port``. Depending on the
1843 :option:`protocol` used, the :option:`hostname`, :option:`port`,
1844 :option:`listen` and :option:`filename` options are used to specify
1845 what sort of connection to make, while the :option:`protocol` option
1846 determines which protocol will be used. This engine defines engine
1847 specific options.
1848
1849 **netsplice**
1850 Like **net**, but uses :manpage:`splice(2)` and
1851 :manpage:`vmsplice(2)` to map data and send/receive.
1852 This engine defines engine specific options.
1853
1854 **cpuio**
1855 Doesn't transfer any data, but burns CPU cycles according to the
1856 :option:`cpuload` and :option:`cpuchunks` options. Setting
9207a0cb 1857 :option:`cpuload`\=85 will cause that job to do nothing but burn 85%
71aa48eb 1858 of the CPU. In case of SMP machines, use :option:`numjobs`\=<nr_of_cpu>
f50fbdda 1859 to get desired CPU usage, as the cpuload only loads a
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1860 single CPU at the desired rate. A job never finishes unless there is
1861 at least one non-cpuio job.
1862
1863 **guasi**
804c0839 1864 The GUASI I/O engine is the Generic Userspace Asynchronous Syscall
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1865 Interface approach to async I/O. See
1866
1867 http://www.xmailserver.org/guasi-lib.html
1868
1869 for more info on GUASI.
1870
1871 **rdma**
1872 The RDMA I/O engine supports both RDMA memory semantics
1873 (RDMA_WRITE/RDMA_READ) and channel semantics (Send/Recv) for the
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1874 InfiniBand, RoCE and iWARP protocols. This engine defines engine
1875 specific options.
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1876
1877 **falloc**
1878 I/O engine that does regular fallocate to simulate data transfer as
1879 fio ioengine.
1880
1881 DDIR_READ
1882 does fallocate(,mode = FALLOC_FL_KEEP_SIZE,).
1883
1884 DDIR_WRITE
1885 does fallocate(,mode = 0).
1886
1887 DDIR_TRIM
1888 does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE).
1889
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1890 **ftruncate**
1891 I/O engine that sends :manpage:`ftruncate(2)` operations in response
1892 to write (DDIR_WRITE) events. Each ftruncate issued sets the file's
f50fbdda 1893 size to the current block offset. :option:`blocksize` is ignored.
761cd093 1894
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1895 **e4defrag**
1896 I/O engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate
1897 defragment activity in request to DDIR_WRITE event.
1898
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1899 **rados**
1900 I/O engine supporting direct access to Ceph Reliable Autonomic
1901 Distributed Object Store (RADOS) via librados. This ioengine
1902 defines engine specific options.
1903
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1904 **rbd**
1905 I/O engine supporting direct access to Ceph Rados Block Devices
1906 (RBD) via librbd without the need to use the kernel rbd driver. This
1907 ioengine defines engine specific options.
1908
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1909 **http**
1910 I/O engine supporting GET/PUT requests over HTTP(S) with libcurl to
1911 a WebDAV or S3 endpoint. This ioengine defines engine specific options.
1912
1913 This engine only supports direct IO of iodepth=1; you need to scale this
1914 via numjobs. blocksize defines the size of the objects to be created.
1915
1916 TRIM is translated to object deletion.
1917
f80dba8d 1918 **gfapi**
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1919 Using GlusterFS libgfapi sync interface to direct access to
1920 GlusterFS volumes without having to go through FUSE. This ioengine
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1921 defines engine specific options.
1922
1923 **gfapi_async**
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1924 Using GlusterFS libgfapi async interface to direct access to
1925 GlusterFS volumes without having to go through FUSE. This ioengine
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1926 defines engine specific options.
1927
1928 **libhdfs**
f50fbdda 1929 Read and write through Hadoop (HDFS). The :option:`filename` option
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1930 is used to specify host,port of the hdfs name-node to connect. This
1931 engine interprets offsets a little differently. In HDFS, files once
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1932 created cannot be modified so random writes are not possible. To
1933 imitate this the libhdfs engine expects a bunch of small files to be
1934 created over HDFS and will randomly pick a file from them
1935 based on the offset generated by fio backend (see the example
f80dba8d 1936 job file to create such files, use ``rw=write`` option). Please
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1937 note, it may be necessary to set environment variables to work
1938 with HDFS/libhdfs properly. Each job uses its own connection to
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1939 HDFS.
1940
1941 **mtd**
1942 Read, write and erase an MTD character device (e.g.,
1943 :file:`/dev/mtd0`). Discards are treated as erases. Depending on the
1944 underlying device type, the I/O may have to go in a certain pattern,
1945 e.g., on NAND, writing sequentially to erase blocks and discarding
c298ee71 1946 before overwriting. The `trimwrite` mode works well for this
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1947 constraint.
1948
1949 **pmemblk**
1950 Read and write using filesystem DAX to a file on a filesystem
363a5f65 1951 mounted with DAX on a persistent memory device through the PMDK
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1952 libpmemblk library.
1953
1954 **dev-dax**
1955 Read and write using device DAX to a persistent memory device (e.g.,
363a5f65 1956 /dev/dax0.0) through the PMDK libpmem library.
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1957
1958 **external**
1959 Prefix to specify loading an external I/O engine object file. Append
c60ebc45 1960 the engine filename, e.g. ``ioengine=external:/tmp/foo.o`` to load
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1961 ioengine :file:`foo.o` in :file:`/tmp`. The path can be either
1962 absolute or relative. See :file:`engines/skeleton_external.c` for
1963 details of writing an external I/O engine.
f80dba8d 1964
1216cc5a 1965 **filecreate**
b71968b1 1966 Simply create the files and do no I/O to them. You still need to
1216cc5a 1967 set `filesize` so that all the accounting still occurs, but no
b71968b1 1968 actual I/O will be done other than creating the file.
f80dba8d 1969
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1970 **libpmem**
1971 Read and write using mmap I/O to a file on a filesystem
363a5f65 1972 mounted with DAX on a persistent memory device through the PMDK
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1973 libpmem library.
1974
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1975 **ime_psync**
1976 Synchronous read and write using DDN's Infinite Memory Engine (IME).
1977 This engine is very basic and issues calls to IME whenever an IO is
1978 queued.
1979
1980 **ime_psyncv**
1981 Synchronous read and write using DDN's Infinite Memory Engine (IME).
1982 This engine uses iovecs and will try to stack as much IOs as possible
1983 (if the IOs are "contiguous" and the IO depth is not exceeded)
1984 before issuing a call to IME.
1985
1986 **ime_aio**
1987 Asynchronous read and write using DDN's Infinite Memory Engine (IME).
1988 This engine will try to stack as much IOs as possible by creating
1989 requests for IME. FIO will then decide when to commit these requests.
1990
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1991I/O engine specific parameters
1992~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1993
1994In addition, there are some parameters which are only valid when a specific
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1995:option:`ioengine` is in use. These are used identically to normal parameters,
1996with the caveat that when used on the command line, they must come after the
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1997:option:`ioengine` that defines them is selected.
1998
1999.. option:: userspace_reap : [libaio]
2000
2001 Normally, with the libaio engine in use, fio will use the
2002 :manpage:`io_getevents(2)` system call to reap newly returned events. With
2003 this flag turned on, the AIO ring will be read directly from user-space to
2004 reap events. The reaping mode is only enabled when polling for a minimum of
c60ebc45 2005 0 events (e.g. when :option:`iodepth_batch_complete` `=0`).
f80dba8d 2006
9d25d068 2007.. option:: hipri : [pvsync2]
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2008
2009 Set RWF_HIPRI on I/O, indicating to the kernel that it's of higher priority
2010 than normal.
2011
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2012.. option:: hipri_percentage : [pvsync2]
2013
f50fbdda 2014 When hipri is set this determines the probability of a pvsync2 I/O being high
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2015 priority. The default is 100%.
2016
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2017.. option:: cpuload=int : [cpuio]
2018
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2019 Attempt to use the specified percentage of CPU cycles. This is a mandatory
2020 option when using cpuio I/O engine.
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2021
2022.. option:: cpuchunks=int : [cpuio]
2023
2024 Split the load into cycles of the given time. In microseconds.
2025
2026.. option:: exit_on_io_done=bool : [cpuio]
2027
2028 Detect when I/O threads are done, then exit.
2029
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2030.. option:: namenode=str : [libhdfs]
2031
22413915 2032 The hostname or IP address of a HDFS cluster namenode to contact.
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2033
2034.. option:: port=int
2035
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2036 [libhdfs]
2037
2038 The listening port of the HFDS cluster namenode.
2039
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2040 [netsplice], [net]
2041
2042 The TCP or UDP port to bind to or connect to. If this is used with
2043 :option:`numjobs` to spawn multiple instances of the same job type, then
2044 this will be the starting port number since fio will use a range of
2045 ports.
2046
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2047 [rdma]
2048
2049 The port to use for RDMA-CM communication. This should be the same value
2050 on the client and the server side.
2051
2052.. option:: hostname=str : [netsplice] [net] [rdma]
f80dba8d 2053
609ac152
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2054 The hostname or IP address to use for TCP, UDP or RDMA-CM based I/O. If the job
2055 is a TCP listener or UDP reader, the hostname is not used and must be omitted
f50fbdda 2056 unless it is a valid UDP multicast address.
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2057
2058.. option:: interface=str : [netsplice] [net]
2059
2060 The IP address of the network interface used to send or receive UDP
2061 multicast.
2062
2063.. option:: ttl=int : [netsplice] [net]
2064
2065 Time-to-live value for outgoing UDP multicast packets. Default: 1.
2066
2067.. option:: nodelay=bool : [netsplice] [net]
2068
2069 Set TCP_NODELAY on TCP connections.
2070
f50fbdda 2071.. option:: protocol=str, proto=str : [netsplice] [net]
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2072
2073 The network protocol to use. Accepted values are:
2074
2075 **tcp**
2076 Transmission control protocol.
2077 **tcpv6**
2078 Transmission control protocol V6.
2079 **udp**
2080 User datagram protocol.
2081 **udpv6**
2082 User datagram protocol V6.
2083 **unix**
2084 UNIX domain socket.
2085
2086 When the protocol is TCP or UDP, the port must also be given, as well as the
2087 hostname if the job is a TCP listener or UDP reader. For unix sockets, the
f50fbdda 2088 normal :option:`filename` option should be used and the port is invalid.
f80dba8d 2089
e9184ec1 2090.. option:: listen : [netsplice] [net]
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2091
2092 For TCP network connections, tell fio to listen for incoming connections
2093 rather than initiating an outgoing connection. The :option:`hostname` must
2094 be omitted if this option is used.
2095
e9184ec1 2096.. option:: pingpong : [netsplice] [net]
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2097
2098 Normally a network writer will just continue writing data, and a network
2099 reader will just consume packages. If ``pingpong=1`` is set, a writer will
2100 send its normal payload to the reader, then wait for the reader to send the
2101 same payload back. This allows fio to measure network latencies. The
2102 submission and completion latencies then measure local time spent sending or
2103 receiving, and the completion latency measures how long it took for the
2104 other end to receive and send back. For UDP multicast traffic
2105 ``pingpong=1`` should only be set for a single reader when multiple readers
2106 are listening to the same address.
2107
e9184ec1 2108.. option:: window_size : [netsplice] [net]
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2109
2110 Set the desired socket buffer size for the connection.
2111
e9184ec1 2112.. option:: mss : [netsplice] [net]
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2113
2114 Set the TCP maximum segment size (TCP_MAXSEG).
2115
2116.. option:: donorname=str : [e4defrag]
2117
730bd7d9 2118 File will be used as a block donor (swap extents between files).
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2119
2120.. option:: inplace=int : [e4defrag]
2121
2122 Configure donor file blocks allocation strategy:
2123
2124 **0**
2125 Default. Preallocate donor's file on init.
2126 **1**
2b455dbf 2127 Allocate space immediately inside defragment event, and free right
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2128 after event.
2129
f3f96717 2130.. option:: clustername=str : [rbd,rados]
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2131
2132 Specifies the name of the Ceph cluster.
2133
2134.. option:: rbdname=str : [rbd]
2135
2136 Specifies the name of the RBD.
2137
f3f96717 2138.. option:: pool=str : [rbd,rados]
f80dba8d 2139
f3f96717 2140 Specifies the name of the Ceph pool containing RBD or RADOS data.
f80dba8d 2141
f3f96717 2142.. option:: clientname=str : [rbd,rados]
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2143
2144 Specifies the username (without the 'client.' prefix) used to access the
2145 Ceph cluster. If the *clustername* is specified, the *clientname* shall be
2146 the full *type.id* string. If no type. prefix is given, fio will add
2147 'client.' by default.
2148
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2149.. option:: busy_poll=bool : [rbd,rados]
2150
2151 Poll store instead of waiting for completion. Usually this provides better
2152 throughput at cost of higher(up to 100%) CPU utilization.
2153
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2154.. option:: skip_bad=bool : [mtd]
2155
2156 Skip operations against known bad blocks.
2157
2158.. option:: hdfsdirectory : [libhdfs]
2159
2160 libhdfs will create chunk in this HDFS directory.
2161
2162.. option:: chunk_size : [libhdfs]
2163
2b455dbf 2164 The size of the chunk to use for each file.
f80dba8d 2165
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2166.. option:: verb=str : [rdma]
2167
2168 The RDMA verb to use on this side of the RDMA ioengine connection. Valid
2169 values are write, read, send and recv. These correspond to the equivalent
2170 RDMA verbs (e.g. write = rdma_write etc.). Note that this only needs to be
2171 specified on the client side of the connection. See the examples folder.
2172
2173.. option:: bindname=str : [rdma]
2174
2175 The name to use to bind the local RDMA-CM connection to a local RDMA device.
2176 This could be a hostname or an IPv4 or IPv6 address. On the server side this
2177 will be passed into the rdma_bind_addr() function and on the client site it
2178 will be used in the rdma_resolve_add() function. This can be useful when
2179 multiple paths exist between the client and the server or in certain loopback
2180 configurations.
f80dba8d 2181
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2182.. option:: readfua=bool : [sg]
2183
2184 With readfua option set to 1, read operations include
2185 the force unit access (fua) flag. Default is 0.
2186
2187.. option:: writefua=bool : [sg]
2188
2189 With writefua option set to 1, write operations include
2190 the force unit access (fua) flag. Default is 0.
2191
2c3a9150 2192.. option:: sg_write_mode=str : [sg]
3740cfc8 2193
2c3a9150
VF
2194 Specify the type of write commands to issue. This option can take three values:
2195
2196 **write**
2197 This is the default where write opcodes are issued as usual.
2198 **verify**
2199 Issue WRITE AND VERIFY commands. The BYTCHK bit is set to 0. This
2200 directs the device to carry out a medium verification with no data
2201 comparison. The writefua option is ignored with this selection.
2202 **same**
2203 Issue WRITE SAME commands. This transfers a single block to the device
2204 and writes this same block of data to a contiguous sequence of LBAs
2205 beginning at the specified offset. fio's block size parameter specifies
2206 the amount of data written with each command. However, the amount of data
2207 actually transferred to the device is equal to the device's block
2208 (sector) size. For a device with 512 byte sectors, blocksize=8k will
2209 write 16 sectors with each command. fio will still generate 8k of data
2210 for each command but only the first 512 bytes will be used and
2211 transferred to the device. The writefua option is ignored with this
2212 selection.
52b81b7c 2213
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2214.. option:: http_host=str : [http]
2215
2216 Hostname to connect to. For S3, this could be the bucket hostname.
2217 Default is **localhost**
2218
2219.. option:: http_user=str : [http]
2220
2221 Username for HTTP authentication.
2222
2223.. option:: http_pass=str : [http]
2224
2225 Password for HTTP authentication.
2226
09fd2966 2227.. option:: https=str : [http]
c2f6a13d 2228
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2229 Enable HTTPS instead of http. *on* enables HTTPS; *insecure*
2230 will enable HTTPS, but disable SSL peer verification (use with
2231 caution!). Default is **off**
c2f6a13d 2232
09fd2966 2233.. option:: http_mode=str : [http]
c2f6a13d 2234
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2235 Which HTTP access mode to use: *webdav*, *swift*, or *s3*.
2236 Default is **webdav**
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2237
2238.. option:: http_s3_region=str : [http]
2239
2240 The S3 region/zone string.
2241 Default is **us-east-1**
2242
2243.. option:: http_s3_key=str : [http]
2244
2245 The S3 secret key.
2246
2247.. option:: http_s3_keyid=str : [http]
2248
2249 The S3 key/access id.
2250
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2251.. option:: http_swift_auth_token=str : [http]
2252
2253 The Swift auth token. See the example configuration file on how
2254 to retrieve this.
2255
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2256.. option:: http_verbose=int : [http]
2257
2258 Enable verbose requests from libcurl. Useful for debugging. 1
2259 turns on verbose logging from libcurl, 2 additionally enables
2260 HTTP IO tracing. Default is **0**
2261
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2262I/O depth
2263~~~~~~~~~
2264
2265.. option:: iodepth=int
2266
2267 Number of I/O units to keep in flight against the file. Note that
2268 increasing *iodepth* beyond 1 will not affect synchronous ioengines (except
c60ebc45 2269 for small degrees when :option:`verify_async` is in use). Even async
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2270 engines may impose OS restrictions causing the desired depth not to be
2271 achieved. This may happen on Linux when using libaio and not setting
9207a0cb 2272 :option:`direct`\=1, since buffered I/O is not async on that OS. Keep an
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2273 eye on the I/O depth distribution in the fio output to verify that the
2274 achieved depth is as expected. Default: 1.
2275
2276.. option:: iodepth_batch_submit=int, iodepth_batch=int
2277
2278 This defines how many pieces of I/O to submit at once. It defaults to 1
2279 which means that we submit each I/O as soon as it is available, but can be
2280 raised to submit bigger batches of I/O at the time. If it is set to 0 the
2281 :option:`iodepth` value will be used.
2282
2283.. option:: iodepth_batch_complete_min=int, iodepth_batch_complete=int
2284
2285 This defines how many pieces of I/O to retrieve at once. It defaults to 1
2286 which means that we'll ask for a minimum of 1 I/O in the retrieval process
2287 from the kernel. The I/O retrieval will go on until we hit the limit set by
2288 :option:`iodepth_low`. If this variable is set to 0, then fio will always
2289 check for completed events before queuing more I/O. This helps reduce I/O
2290 latency, at the cost of more retrieval system calls.
2291
2292.. option:: iodepth_batch_complete_max=int
2293
2294 This defines maximum pieces of I/O to retrieve at once. This variable should
9207a0cb 2295 be used along with :option:`iodepth_batch_complete_min`\=int variable,
f80dba8d 2296 specifying the range of min and max amount of I/O which should be
730bd7d9 2297 retrieved. By default it is equal to the :option:`iodepth_batch_complete_min`
f80dba8d
MT
2298 value.
2299
2300 Example #1::
2301
2302 iodepth_batch_complete_min=1
2303 iodepth_batch_complete_max=<iodepth>
2304
2305 which means that we will retrieve at least 1 I/O and up to the whole
2306 submitted queue depth. If none of I/O has been completed yet, we will wait.
2307
2308 Example #2::
2309
2310 iodepth_batch_complete_min=0
2311 iodepth_batch_complete_max=<iodepth>
2312
2313 which means that we can retrieve up to the whole submitted queue depth, but
2314 if none of I/O has been completed yet, we will NOT wait and immediately exit
2315 the system call. In this example we simply do polling.
2316
2317.. option:: iodepth_low=int
2318
2319 The low water mark indicating when to start filling the queue
2320 again. Defaults to the same as :option:`iodepth`, meaning that fio will
2321 attempt to keep the queue full at all times. If :option:`iodepth` is set to
c60ebc45 2322 e.g. 16 and *iodepth_low* is set to 4, then after fio has filled the queue of
f80dba8d
MT
2323 16 requests, it will let the depth drain down to 4 before starting to fill
2324 it again.
2325
997b5680
SW
2326.. option:: serialize_overlap=bool
2327
2328 Serialize in-flight I/Os that might otherwise cause or suffer from data races.
2329 When two or more I/Os are submitted simultaneously, there is no guarantee that
2330 the I/Os will be processed or completed in the submitted order. Further, if
2331 two or more of those I/Os are writes, any overlapping region between them can
2332 become indeterminate/undefined on certain storage. These issues can cause
2333 verification to fail erratically when at least one of the racing I/Os is
2334 changing data and the overlapping region has a non-zero size. Setting
2335 ``serialize_overlap`` tells fio to avoid provoking this behavior by explicitly
2336 serializing in-flight I/Os that have a non-zero overlap. Note that setting
ee21ebee 2337 this option can reduce both performance and the :option:`iodepth` achieved.
997b5680
SW
2338 Additionally this option does not work when :option:`io_submit_mode` is set to
2339 offload. Default: false.
2340
f80dba8d
MT
2341.. option:: io_submit_mode=str
2342
2343 This option controls how fio submits the I/O to the I/O engine. The default
2344 is `inline`, which means that the fio job threads submit and reap I/O
2345 directly. If set to `offload`, the job threads will offload I/O submission
2346 to a dedicated pool of I/O threads. This requires some coordination and thus
2347 has a bit of extra overhead, especially for lower queue depth I/O where it
2348 can increase latencies. The benefit is that fio can manage submission rates
2349 independently of the device completion rates. This avoids skewed latency
730bd7d9 2350 reporting if I/O gets backed up on the device side (the coordinated omission
f80dba8d
MT
2351 problem).
2352
2353
2354I/O rate
2355~~~~~~~~
2356
a881438b 2357.. option:: thinktime=time
f80dba8d 2358
f75ede1d
SW
2359 Stall the job for the specified period of time after an I/O has completed before issuing the
2360 next. May be used to simulate processing being done by an application.
947e0fe0 2361 When the unit is omitted, the value is interpreted in microseconds. See
f80dba8d
MT
2362 :option:`thinktime_blocks` and :option:`thinktime_spin`.
2363
a881438b 2364.. option:: thinktime_spin=time
f80dba8d
MT
2365
2366 Only valid if :option:`thinktime` is set - pretend to spend CPU time doing
2367 something with the data received, before falling back to sleeping for the
f75ede1d 2368 rest of the period specified by :option:`thinktime`. When the unit is
947e0fe0 2369 omitted, the value is interpreted in microseconds.
f80dba8d
MT
2370
2371.. option:: thinktime_blocks=int
2372
2373 Only valid if :option:`thinktime` is set - control how many blocks to issue,
f50fbdda
TK
2374 before waiting :option:`thinktime` usecs. If not set, defaults to 1 which will make
2375 fio wait :option:`thinktime` usecs after every block. This effectively makes any
f80dba8d 2376 queue depth setting redundant, since no more than 1 I/O will be queued
f50fbdda 2377 before we have to complete it and do our :option:`thinktime`. In other words, this
f80dba8d 2378 setting effectively caps the queue depth if the latter is larger.
71bfa161 2379
f80dba8d 2380.. option:: rate=int[,int][,int]
71bfa161 2381
f80dba8d
MT
2382 Cap the bandwidth used by this job. The number is in bytes/sec, the normal
2383 suffix rules apply. Comma-separated values may be specified for reads,
2384 writes, and trims as described in :option:`blocksize`.
71bfa161 2385
b25b3464
SW
2386 For example, using `rate=1m,500k` would limit reads to 1MiB/sec and writes to
2387 500KiB/sec. Capping only reads or writes can be done with `rate=,500k` or
2388 `rate=500k,` where the former will only limit writes (to 500KiB/sec) and the
2389 latter will only limit reads.
2390
f80dba8d 2391.. option:: rate_min=int[,int][,int]
71bfa161 2392
f80dba8d
MT
2393 Tell fio to do whatever it can to maintain at least this bandwidth. Failing
2394 to meet this requirement will cause the job to exit. Comma-separated values
2395 may be specified for reads, writes, and trims as described in
2396 :option:`blocksize`.
71bfa161 2397
f80dba8d 2398.. option:: rate_iops=int[,int][,int]
71bfa161 2399
f80dba8d
MT
2400 Cap the bandwidth to this number of IOPS. Basically the same as
2401 :option:`rate`, just specified independently of bandwidth. If the job is
2402 given a block size range instead of a fixed value, the smallest block size
2403 is used as the metric. Comma-separated values may be specified for reads,
2404 writes, and trims as described in :option:`blocksize`.
71bfa161 2405
f80dba8d 2406.. option:: rate_iops_min=int[,int][,int]
71bfa161 2407
f80dba8d
MT
2408 If fio doesn't meet this rate of I/O, it will cause the job to exit.
2409 Comma-separated values may be specified for reads, writes, and trims as
2410 described in :option:`blocksize`.
71bfa161 2411
f80dba8d 2412.. option:: rate_process=str
66c098b8 2413
f80dba8d
MT
2414 This option controls how fio manages rated I/O submissions. The default is
2415 `linear`, which submits I/O in a linear fashion with fixed delays between
c60ebc45 2416 I/Os that gets adjusted based on I/O completion rates. If this is set to
f80dba8d
MT
2417 `poisson`, fio will submit I/O based on a more real world random request
2418 flow, known as the Poisson process
2419 (https://en.wikipedia.org/wiki/Poisson_point_process). The lambda will be
2420 10^6 / IOPS for the given workload.
71bfa161 2421
1a9bf814
JA
2422.. option:: rate_ignore_thinktime=bool
2423
2424 By default, fio will attempt to catch up to the specified rate setting,
2425 if any kind of thinktime setting was used. If this option is set, then
2426 fio will ignore the thinktime and continue doing IO at the specified
2427 rate, instead of entering a catch-up mode after thinktime is done.
2428
71bfa161 2429
f80dba8d
MT
2430I/O latency
2431~~~~~~~~~~~
71bfa161 2432
a881438b 2433.. option:: latency_target=time
71bfa161 2434
f80dba8d 2435 If set, fio will attempt to find the max performance point that the given
f75ede1d 2436 workload will run at while maintaining a latency below this target. When
947e0fe0 2437 the unit is omitted, the value is interpreted in microseconds. See
f75ede1d 2438 :option:`latency_window` and :option:`latency_percentile`.
71bfa161 2439
a881438b 2440.. option:: latency_window=time
71bfa161 2441
f80dba8d 2442 Used with :option:`latency_target` to specify the sample window that the job
f75ede1d 2443 is run at varying queue depths to test the performance. When the unit is
947e0fe0 2444 omitted, the value is interpreted in microseconds.
b4692828 2445
f80dba8d 2446.. option:: latency_percentile=float
71bfa161 2447
c60ebc45 2448 The percentage of I/Os that must fall within the criteria specified by
f80dba8d 2449 :option:`latency_target` and :option:`latency_window`. If not set, this
c60ebc45 2450 defaults to 100.0, meaning that all I/Os must be equal or below to the value
f80dba8d 2451 set by :option:`latency_target`.
71bfa161 2452
a881438b 2453.. option:: max_latency=time
71bfa161 2454
f75ede1d 2455 If set, fio will exit the job with an ETIMEDOUT error if it exceeds this
947e0fe0 2456 maximum latency. When the unit is omitted, the value is interpreted in
f75ede1d 2457 microseconds.
71bfa161 2458
f80dba8d 2459.. option:: rate_cycle=int
71bfa161 2460
f80dba8d 2461 Average bandwidth for :option:`rate` and :option:`rate_min` over this number
a47b697c 2462 of milliseconds. Defaults to 1000.
71bfa161 2463
71bfa161 2464
f80dba8d
MT
2465I/O replay
2466~~~~~~~~~~
71bfa161 2467
f80dba8d 2468.. option:: write_iolog=str
c2b1e753 2469
f80dba8d
MT
2470 Write the issued I/O patterns to the specified file. See
2471 :option:`read_iolog`. Specify a separate file for each job, otherwise the
2472 iologs will be interspersed and the file may be corrupt.
c2b1e753 2473
f80dba8d 2474.. option:: read_iolog=str
71bfa161 2475
22413915 2476 Open an iolog with the specified filename and replay the I/O patterns it
f80dba8d
MT
2477 contains. This can be used to store a workload and replay it sometime
2478 later. The iolog given may also be a blktrace binary file, which allows fio
2479 to replay a workload captured by :command:`blktrace`. See
2480 :manpage:`blktrace(8)` for how to capture such logging data. For blktrace
2481 replay, the file needs to be turned into a blkparse binary data file first
2482 (``blkparse <device> -o /dev/null -d file_for_fio.bin``).
78439a18
JA
2483 You can specify a number of files by separating the names with a ':'
2484 character. See the :option:`filename` option for information on how to
2485 escape ':' and '\' characters within the file names. These files will
2486 be sequentially assigned to job clones created by :option:`numjobs`.
71bfa161 2487
77be374d
AK
2488.. option:: read_iolog_chunked=bool
2489
2490 Determines how iolog is read. If false(default) entire :option:`read_iolog`
2491 will be read at once. If selected true, input from iolog will be read
2492 gradually. Useful when iolog is very large, or it is generated.
2493
589e88b7 2494.. option:: replay_no_stall=bool
71bfa161 2495
f80dba8d 2496 When replaying I/O with :option:`read_iolog` the default behavior is to
22413915 2497 attempt to respect the timestamps within the log and replay them with the
f80dba8d
MT
2498 appropriate delay between IOPS. By setting this variable fio will not
2499 respect the timestamps and attempt to replay them as fast as possible while
2500 still respecting ordering. The result is the same I/O pattern to a given
2501 device, but different timings.
71bfa161 2502
6dd7fa77
JA
2503.. option:: replay_time_scale=int
2504
2505 When replaying I/O with :option:`read_iolog`, fio will honor the
2506 original timing in the trace. With this option, it's possible to scale
2507 the time. It's a percentage option, if set to 50 it means run at 50%
2508 the original IO rate in the trace. If set to 200, run at twice the
2509 original IO rate. Defaults to 100.
2510
f80dba8d 2511.. option:: replay_redirect=str
b4692828 2512
f80dba8d
MT
2513 While replaying I/O patterns using :option:`read_iolog` the default behavior
2514 is to replay the IOPS onto the major/minor device that each IOP was recorded
2515 from. This is sometimes undesirable because on a different machine those
2516 major/minor numbers can map to a different device. Changing hardware on the
2517 same system can also result in a different major/minor mapping.
730bd7d9 2518 ``replay_redirect`` causes all I/Os to be replayed onto the single specified
f80dba8d 2519 device regardless of the device it was recorded
9207a0cb 2520 from. i.e. :option:`replay_redirect`\= :file:`/dev/sdc` would cause all I/O
f80dba8d
MT
2521 in the blktrace or iolog to be replayed onto :file:`/dev/sdc`. This means
2522 multiple devices will be replayed onto a single device, if the trace
2523 contains multiple devices. If you want multiple devices to be replayed
2524 concurrently to multiple redirected devices you must blkparse your trace
2525 into separate traces and replay them with independent fio invocations.
2526 Unfortunately this also breaks the strict time ordering between multiple
2527 device accesses.
71bfa161 2528
f80dba8d 2529.. option:: replay_align=int
74929ac2 2530
f80dba8d
MT
2531 Force alignment of I/O offsets and lengths in a trace to this power of 2
2532 value.
3c54bc46 2533
f80dba8d 2534.. option:: replay_scale=int
3c54bc46 2535
f80dba8d 2536 Scale sector offsets down by this factor when replaying traces.
3c54bc46 2537
38f68906
JA
2538.. option:: replay_skip=str
2539
2540 Sometimes it's useful to skip certain IO types in a replay trace.
2541 This could be, for instance, eliminating the writes in the trace.
2542 Or not replaying the trims/discards, if you are redirecting to
2543 a device that doesn't support them. This option takes a comma
2544 separated list of read, write, trim, sync.
2545
3c54bc46 2546
f80dba8d
MT
2547Threads, processes and job synchronization
2548~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3c54bc46 2549
f80dba8d 2550.. option:: thread
3c54bc46 2551
730bd7d9
SW
2552 Fio defaults to creating jobs by using fork, however if this option is
2553 given, fio will create jobs by using POSIX Threads' function
2554 :manpage:`pthread_create(3)` to create threads instead.
71bfa161 2555
f80dba8d 2556.. option:: wait_for=str
74929ac2 2557
730bd7d9
SW
2558 If set, the current job won't be started until all workers of the specified
2559 waitee job are done.
74929ac2 2560
f80dba8d
MT
2561 ``wait_for`` operates on the job name basis, so there are a few
2562 limitations. First, the waitee must be defined prior to the waiter job
2563 (meaning no forward references). Second, if a job is being referenced as a
2564 waitee, it must have a unique name (no duplicate waitees).
74929ac2 2565
f80dba8d 2566.. option:: nice=int
892a6ffc 2567
f80dba8d 2568 Run the job with the given nice value. See man :manpage:`nice(2)`.
892a6ffc 2569
f80dba8d
MT
2570 On Windows, values less than -15 set the process class to "High"; -1 through
2571 -15 set "Above Normal"; 1 through 15 "Below Normal"; and above 15 "Idle"
2572 priority class.
74929ac2 2573
f80dba8d 2574.. option:: prio=int
71bfa161 2575
f80dba8d
MT
2576 Set the I/O priority value of this job. Linux limits us to a positive value
2577 between 0 and 7, with 0 being the highest. See man
2578 :manpage:`ionice(1)`. Refer to an appropriate manpage for other operating
2579 systems since meaning of priority may differ.
71bfa161 2580
f80dba8d 2581.. option:: prioclass=int
d59aa780 2582
f80dba8d 2583 Set the I/O priority class. See man :manpage:`ionice(1)`.
d59aa780 2584
f80dba8d 2585.. option:: cpus_allowed=str
6d500c2e 2586
730bd7d9 2587 Controls the same options as :option:`cpumask`, but accepts a textual
b570e037
SW
2588 specification of the permitted CPUs instead and CPUs are indexed from 0. So
2589 to use CPUs 0 and 5 you would specify ``cpus_allowed=0,5``. This option also
2590 allows a range of CPUs to be specified -- say you wanted a binding to CPUs
2591 0, 5, and 8 to 15, you would set ``cpus_allowed=0,5,8-15``.
2592
2593 On Windows, when ``cpus_allowed`` is unset only CPUs from fio's current
2594 processor group will be used and affinity settings are inherited from the
2595 system. An fio build configured to target Windows 7 makes options that set
2596 CPUs processor group aware and values will set both the processor group
2597 and a CPU from within that group. For example, on a system where processor
2598 group 0 has 40 CPUs and processor group 1 has 32 CPUs, ``cpus_allowed``
2599 values between 0 and 39 will bind CPUs from processor group 0 and
2600 ``cpus_allowed`` values between 40 and 71 will bind CPUs from processor
2601 group 1. When using ``cpus_allowed_policy=shared`` all CPUs specified by a
2602 single ``cpus_allowed`` option must be from the same processor group. For
2603 Windows fio builds not built for Windows 7, CPUs will only be selected from
2604 (and be relative to) whatever processor group fio happens to be running in
2605 and CPUs from other processor groups cannot be used.
6d500c2e 2606
f80dba8d 2607.. option:: cpus_allowed_policy=str
6d500c2e 2608
f80dba8d 2609 Set the policy of how fio distributes the CPUs specified by
730bd7d9 2610 :option:`cpus_allowed` or :option:`cpumask`. Two policies are supported:
6d500c2e 2611
f80dba8d
MT
2612 **shared**
2613 All jobs will share the CPU set specified.
2614 **split**
2615 Each job will get a unique CPU from the CPU set.
6d500c2e 2616
22413915 2617 **shared** is the default behavior, if the option isn't specified. If
f80dba8d
MT
2618 **split** is specified, then fio will will assign one cpu per job. If not
2619 enough CPUs are given for the jobs listed, then fio will roundrobin the CPUs
2620 in the set.
6d500c2e 2621
b570e037
SW
2622.. option:: cpumask=int
2623
2624 Set the CPU affinity of this job. The parameter given is a bit mask of
2625 allowed CPUs the job may run on. So if you want the allowed CPUs to be 1
2626 and 5, you would pass the decimal value of (1 << 1 | 1 << 5), or 34. See man
2627 :manpage:`sched_setaffinity(2)`. This may not work on all supported
2628 operating systems or kernel versions. This option doesn't work well for a
2629 higher CPU count than what you can store in an integer mask, so it can only
2630 control cpus 1-32. For boxes with larger CPU counts, use
2631 :option:`cpus_allowed`.
2632
f80dba8d 2633.. option:: numa_cpu_nodes=str
6d500c2e 2634
f80dba8d
MT
2635 Set this job running on specified NUMA nodes' CPUs. The arguments allow
2636 comma delimited list of cpu numbers, A-B ranges, or `all`. Note, to enable
ac8ca2af 2637 NUMA options support, fio must be built on a system with libnuma-dev(el)
f80dba8d 2638 installed.
61b9861d 2639
f80dba8d 2640.. option:: numa_mem_policy=str
61b9861d 2641
f80dba8d
MT
2642 Set this job's memory policy and corresponding NUMA nodes. Format of the
2643 arguments::
5c94b008 2644
f80dba8d 2645 <mode>[:<nodelist>]
ce35b1ec 2646
804c0839 2647 ``mode`` is one of the following memory policies: ``default``, ``prefer``,
730bd7d9
SW
2648 ``bind``, ``interleave`` or ``local``. For ``default`` and ``local`` memory
2649 policies, no node needs to be specified. For ``prefer``, only one node is
2650 allowed. For ``bind`` and ``interleave`` the ``nodelist`` may be as
2651 follows: a comma delimited list of numbers, A-B ranges, or `all`.
71bfa161 2652
f80dba8d 2653.. option:: cgroup=str
390b1537 2654
f80dba8d
MT
2655 Add job to this control group. If it doesn't exist, it will be created. The
2656 system must have a mounted cgroup blkio mount point for this to work. If
2657 your system doesn't have it mounted, you can do so with::
5af1c6f3 2658
f80dba8d 2659 # mount -t cgroup -o blkio none /cgroup
5af1c6f3 2660
f80dba8d 2661.. option:: cgroup_weight=int
5af1c6f3 2662
f80dba8d
MT
2663 Set the weight of the cgroup to this value. See the documentation that comes
2664 with the kernel, allowed values are in the range of 100..1000.
a086c257 2665
f80dba8d 2666.. option:: cgroup_nodelete=bool
8c07860d 2667
f80dba8d
MT
2668 Normally fio will delete the cgroups it has created after the job
2669 completion. To override this behavior and to leave cgroups around after the
2670 job completion, set ``cgroup_nodelete=1``. This can be useful if one wants
2671 to inspect various cgroup files after job completion. Default: false.
8c07860d 2672
f80dba8d 2673.. option:: flow_id=int
8c07860d 2674
f80dba8d
MT
2675 The ID of the flow. If not specified, it defaults to being a global
2676 flow. See :option:`flow`.
1907dbc6 2677
f80dba8d 2678.. option:: flow=int
71bfa161 2679
f80dba8d
MT
2680 Weight in token-based flow control. If this value is used, then there is a
2681 'flow counter' which is used to regulate the proportion of activity between
2682 two or more jobs. Fio attempts to keep this flow counter near zero. The
2683 ``flow`` parameter stands for how much should be added or subtracted to the
2684 flow counter on each iteration of the main I/O loop. That is, if one job has
2685 ``flow=8`` and another job has ``flow=-1``, then there will be a roughly 1:8
2686 ratio in how much one runs vs the other.
71bfa161 2687
f80dba8d 2688.. option:: flow_watermark=int
a31041ea 2689
f80dba8d
MT
2690 The maximum value that the absolute value of the flow counter is allowed to
2691 reach before the job must wait for a lower value of the counter.
82407585 2692
f80dba8d 2693.. option:: flow_sleep=int
82407585 2694
f80dba8d
MT
2695 The period of time, in microseconds, to wait after the flow watermark has
2696 been exceeded before retrying operations.
82407585 2697
f80dba8d 2698.. option:: stonewall, wait_for_previous
82407585 2699
f80dba8d
MT
2700 Wait for preceding jobs in the job file to exit, before starting this
2701 one. Can be used to insert serialization points in the job file. A stone
2702 wall also implies starting a new reporting group, see
2703 :option:`group_reporting`.
2704
2705.. option:: exitall
2706
730bd7d9
SW
2707 By default, fio will continue running all other jobs when one job finishes
2708 but sometimes this is not the desired action. Setting ``exitall`` will
2709 instead make fio terminate all other jobs when one job finishes.
f80dba8d
MT
2710
2711.. option:: exec_prerun=str
2712
2713 Before running this job, issue the command specified through
2714 :manpage:`system(3)`. Output is redirected in a file called
2715 :file:`jobname.prerun.txt`.
2716
2717.. option:: exec_postrun=str
2718
2719 After the job completes, issue the command specified though
2720 :manpage:`system(3)`. Output is redirected in a file called
2721 :file:`jobname.postrun.txt`.
2722
2723.. option:: uid=int
2724
2725 Instead of running as the invoking user, set the user ID to this value
2726 before the thread/process does any work.
2727
2728.. option:: gid=int
2729
2730 Set group ID, see :option:`uid`.
2731
2732
2733Verification
2734~~~~~~~~~~~~
2735
2736.. option:: verify_only
2737
2738 Do not perform specified workload, only verify data still matches previous
2739 invocation of this workload. This option allows one to check data multiple
2740 times at a later date without overwriting it. This option makes sense only
2741 for workloads that write data, and does not support workloads with the
2742 :option:`time_based` option set.
2743
2744.. option:: do_verify=bool
2745
2746 Run the verify phase after a write phase. Only valid if :option:`verify` is
2747 set. Default: true.
2748
2749.. option:: verify=str
2750
2751 If writing to a file, fio can verify the file contents after each iteration
2752 of the job. Each verification method also implies verification of special
2753 header, which is written to the beginning of each block. This header also
2754 includes meta information, like offset of the block, block number, timestamp
2755 when block was written, etc. :option:`verify` can be combined with
2756 :option:`verify_pattern` option. The allowed values are:
2757
2758 **md5**
2759 Use an md5 sum of the data area and store it in the header of
2760 each block.
2761
2762 **crc64**
2763 Use an experimental crc64 sum of the data area and store it in the
2764 header of each block.
2765
2766 **crc32c**
a5896300
SW
2767 Use a crc32c sum of the data area and store it in the header of
2768 each block. This will automatically use hardware acceleration
2769 (e.g. SSE4.2 on an x86 or CRC crypto extensions on ARM64) but will
2770 fall back to software crc32c if none is found. Generally the
804c0839 2771 fastest checksum fio supports when hardware accelerated.
f80dba8d
MT
2772
2773 **crc32c-intel**
a5896300 2774 Synonym for crc32c.
f80dba8d
MT
2775
2776 **crc32**
2777 Use a crc32 sum of the data area and store it in the header of each
2778 block.
2779
2780 **crc16**
2781 Use a crc16 sum of the data area and store it in the header of each
2782 block.
2783
2784 **crc7**
2785 Use a crc7 sum of the data area and store it in the header of each
2786 block.
2787
2788 **xxhash**
2789 Use xxhash as the checksum function. Generally the fastest software
2790 checksum that fio supports.
2791
2792 **sha512**
2793 Use sha512 as the checksum function.
2794
2795 **sha256**
2796 Use sha256 as the checksum function.
2797
2798 **sha1**
2799 Use optimized sha1 as the checksum function.
82407585 2800
ae3a5acc
JA
2801 **sha3-224**
2802 Use optimized sha3-224 as the checksum function.
2803
2804 **sha3-256**
2805 Use optimized sha3-256 as the checksum function.
2806
2807 **sha3-384**
2808 Use optimized sha3-384 as the checksum function.
2809
2810 **sha3-512**
2811 Use optimized sha3-512 as the checksum function.
2812
f80dba8d
MT
2813 **meta**
2814 This option is deprecated, since now meta information is included in
2815 generic verification header and meta verification happens by
2816 default. For detailed information see the description of the
2817 :option:`verify` setting. This option is kept because of
2818 compatibility's sake with old configurations. Do not use it.
2819
2820 **pattern**
2821 Verify a strict pattern. Normally fio includes a header with some
2822 basic information and checksumming, but if this option is set, only
2823 the specific pattern set with :option:`verify_pattern` is verified.
2824
2825 **null**
2826 Only pretend to verify. Useful for testing internals with
9207a0cb 2827 :option:`ioengine`\=null, not for much else.
f80dba8d
MT
2828
2829 This option can be used for repeated burn-in tests of a system to make sure
2830 that the written data is also correctly read back. If the data direction
2831 given is a read or random read, fio will assume that it should verify a
2832 previously written file. If the data direction includes any form of write,
2833 the verify will be of the newly written data.
2834
47e6a6e5
SW
2835 To avoid false verification errors, do not use the norandommap option when
2836 verifying data with async I/O engines and I/O depths > 1. Or use the
2837 norandommap and the lfsr random generator together to avoid writing to the
2838 same offset with muliple outstanding I/Os.
2839
f80dba8d
MT
2840.. option:: verify_offset=int
2841
2842 Swap the verification header with data somewhere else in the block before
2843 writing. It is swapped back before verifying.
2844
2845.. option:: verify_interval=int
2846
2847 Write the verification header at a finer granularity than the
2848 :option:`blocksize`. It will be written for chunks the size of
2849 ``verify_interval``. :option:`blocksize` should divide this evenly.
2850
2851.. option:: verify_pattern=str
2852
2853 If set, fio will fill the I/O buffers with this pattern. Fio defaults to
2854 filling with totally random bytes, but sometimes it's interesting to fill
2855 with a known pattern for I/O verification purposes. Depending on the width
730bd7d9 2856 of the pattern, fio will fill 1/2/3/4 bytes of the buffer at the time (it can
f80dba8d
MT
2857 be either a decimal or a hex number). The ``verify_pattern`` if larger than
2858 a 32-bit quantity has to be a hex number that starts with either "0x" or
2859 "0X". Use with :option:`verify`. Also, ``verify_pattern`` supports %o
2860 format, which means that for each block offset will be written and then
2861 verified back, e.g.::
61b9861d
RP
2862
2863 verify_pattern=%o
2864
f80dba8d
MT
2865 Or use combination of everything::
2866
61b9861d 2867 verify_pattern=0xff%o"abcd"-12
e28218f3 2868
f80dba8d
MT
2869.. option:: verify_fatal=bool
2870
2871 Normally fio will keep checking the entire contents before quitting on a
2872 block verification failure. If this option is set, fio will exit the job on
2873 the first observed failure. Default: false.
2874
2875.. option:: verify_dump=bool
2876
2877 If set, dump the contents of both the original data block and the data block
2878 we read off disk to files. This allows later analysis to inspect just what
2879 kind of data corruption occurred. Off by default.
2880
2881.. option:: verify_async=int
2882
2883 Fio will normally verify I/O inline from the submitting thread. This option
2884 takes an integer describing how many async offload threads to create for I/O
2885 verification instead, causing fio to offload the duty of verifying I/O
2886 contents to one or more separate threads. If using this offload option, even
2887 sync I/O engines can benefit from using an :option:`iodepth` setting higher
2888 than 1, as it allows them to have I/O in flight while verifies are running.
d7e6ea1c 2889 Defaults to 0 async threads, i.e. verification is not asynchronous.
f80dba8d
MT
2890
2891.. option:: verify_async_cpus=str
2892
2893 Tell fio to set the given CPU affinity on the async I/O verification
2894 threads. See :option:`cpus_allowed` for the format used.
2895
2896.. option:: verify_backlog=int
2897
2898 Fio will normally verify the written contents of a job that utilizes verify
2899 once that job has completed. In other words, everything is written then
2900 everything is read back and verified. You may want to verify continually
2901 instead for a variety of reasons. Fio stores the meta data associated with
2902 an I/O block in memory, so for large verify workloads, quite a bit of memory
2903 would be used up holding this meta data. If this option is enabled, fio will
2904 write only N blocks before verifying these blocks.
2905
2906.. option:: verify_backlog_batch=int
2907
2908 Control how many blocks fio will verify if :option:`verify_backlog` is
2909 set. If not set, will default to the value of :option:`verify_backlog`
2910 (meaning the entire queue is read back and verified). If
2911 ``verify_backlog_batch`` is less than :option:`verify_backlog` then not all
2912 blocks will be verified, if ``verify_backlog_batch`` is larger than
2913 :option:`verify_backlog`, some blocks will be verified more than once.
2914
2915.. option:: verify_state_save=bool
2916
2917 When a job exits during the write phase of a verify workload, save its
2918 current state. This allows fio to replay up until that point, if the verify
2919 state is loaded for the verify read phase. The format of the filename is,
2920 roughly::
2921
f50fbdda 2922 <type>-<jobname>-<jobindex>-verify.state.
f80dba8d
MT
2923
2924 <type> is "local" for a local run, "sock" for a client/server socket
2925 connection, and "ip" (192.168.0.1, for instance) for a networked
d7e6ea1c 2926 client/server connection. Defaults to true.
f80dba8d
MT
2927
2928.. option:: verify_state_load=bool
2929
2930 If a verify termination trigger was used, fio stores the current write state
2931 of each thread. This can be used at verification time so that fio knows how
2932 far it should verify. Without this information, fio will run a full
a47b697c
SW
2933 verification pass, according to the settings in the job file used. Default
2934 false.
f80dba8d
MT
2935
2936.. option:: trim_percentage=int
2937
2938 Number of verify blocks to discard/trim.
2939
2940.. option:: trim_verify_zero=bool
2941
22413915 2942 Verify that trim/discarded blocks are returned as zeros.
f80dba8d
MT
2943
2944.. option:: trim_backlog=int
2945
5cfd1e9a 2946 Trim after this number of blocks are written.
f80dba8d
MT
2947
2948.. option:: trim_backlog_batch=int
2949
2950 Trim this number of I/O blocks.
2951
2952.. option:: experimental_verify=bool
2953
2954 Enable experimental verification.
2955
f80dba8d
MT
2956Steady state
2957~~~~~~~~~~~~
2958
2959.. option:: steadystate=str:float, ss=str:float
2960
2961 Define the criterion and limit for assessing steady state performance. The
2962 first parameter designates the criterion whereas the second parameter sets
2963 the threshold. When the criterion falls below the threshold for the
2964 specified duration, the job will stop. For example, `iops_slope:0.1%` will
2965 direct fio to terminate the job when the least squares regression slope
2966 falls below 0.1% of the mean IOPS. If :option:`group_reporting` is enabled
2967 this will apply to all jobs in the group. Below is the list of available
2968 steady state assessment criteria. All assessments are carried out using only
2969 data from the rolling collection window. Threshold limits can be expressed
2970 as a fixed value or as a percentage of the mean in the collection window.
2971
2972 **iops**
2973 Collect IOPS data. Stop the job if all individual IOPS measurements
2974 are within the specified limit of the mean IOPS (e.g., ``iops:2``
2975 means that all individual IOPS values must be within 2 of the mean,
2976 whereas ``iops:0.2%`` means that all individual IOPS values must be
2977 within 0.2% of the mean IOPS to terminate the job).
2978
2979 **iops_slope**
2980 Collect IOPS data and calculate the least squares regression
2981 slope. Stop the job if the slope falls below the specified limit.
2982
2983 **bw**
2984 Collect bandwidth data. Stop the job if all individual bandwidth
2985 measurements are within the specified limit of the mean bandwidth.
2986
2987 **bw_slope**
2988 Collect bandwidth data and calculate the least squares regression
2989 slope. Stop the job if the slope falls below the specified limit.
2990
2991.. option:: steadystate_duration=time, ss_dur=time
2992
2993 A rolling window of this duration will be used to judge whether steady state
2994 has been reached. Data will be collected once per second. The default is 0
f75ede1d 2995 which disables steady state detection. When the unit is omitted, the
947e0fe0 2996 value is interpreted in seconds.
f80dba8d
MT
2997
2998.. option:: steadystate_ramp_time=time, ss_ramp=time
2999
3000 Allow the job to run for the specified duration before beginning data
3001 collection for checking the steady state job termination criterion. The
947e0fe0 3002 default is 0. When the unit is omitted, the value is interpreted in seconds.
f80dba8d
MT
3003
3004
3005Measurements and reporting
3006~~~~~~~~~~~~~~~~~~~~~~~~~~
3007
3008.. option:: per_job_logs=bool
3009
3010 If set, this generates bw/clat/iops log with per file private filenames. If
3011 not set, jobs with identical names will share the log filename. Default:
3012 true.
3013
3014.. option:: group_reporting
3015
3016 It may sometimes be interesting to display statistics for groups of jobs as
3017 a whole instead of for each individual job. This is especially true if
3018 :option:`numjobs` is used; looking at individual thread/process output
3019 quickly becomes unwieldy. To see the final report per-group instead of
3020 per-job, use :option:`group_reporting`. Jobs in a file will be part of the
3021 same reporting group, unless if separated by a :option:`stonewall`, or by
3022 using :option:`new_group`.
3023
3024.. option:: new_group
3025
3026 Start a new reporting group. See: :option:`group_reporting`. If not given,
3027 all jobs in a file will be part of the same reporting group, unless
3028 separated by a :option:`stonewall`.
3029
589e88b7 3030.. option:: stats=bool
8243be59
JA
3031
3032 By default, fio collects and shows final output results for all jobs
3033 that run. If this option is set to 0, then fio will ignore it in
3034 the final stat output.
3035
f80dba8d
MT
3036.. option:: write_bw_log=str
3037
3038 If given, write a bandwidth log for this job. Can be used to store data of
074f0817 3039 the bandwidth of the jobs in their lifetime.
f80dba8d 3040
074f0817
SW
3041 If no str argument is given, the default filename of
3042 :file:`jobname_type.x.log` is used. Even when the argument is given, fio
3043 will still append the type of log. So if one specifies::
3044
3045 write_bw_log=foo
f80dba8d 3046
074f0817
SW
3047 The actual log name will be :file:`foo_bw.x.log` where `x` is the index
3048 of the job (`1..N`, where `N` is the number of jobs). If
3049 :option:`per_job_logs` is false, then the filename will not include the
3050 `.x` job index.
e3cedca7 3051
074f0817
SW
3052 The included :command:`fio_generate_plots` script uses :command:`gnuplot` to turn these
3053 text files into nice graphs. See `Log File Formats`_ for how data is
3054 structured within the file.
3055
3056.. option:: write_lat_log=str
e3cedca7 3057
074f0817 3058 Same as :option:`write_bw_log`, except this option creates I/O
77b7e675
SW
3059 submission (e.g., :file:`name_slat.x.log`), completion (e.g.,
3060 :file:`name_clat.x.log`), and total (e.g., :file:`name_lat.x.log`)
074f0817
SW
3061 latency files instead. See :option:`write_bw_log` for details about
3062 the filename format and `Log File Formats`_ for how data is structured
3063 within the files.
be4ecfdf 3064
f80dba8d 3065.. option:: write_hist_log=str
06842027 3066
074f0817 3067 Same as :option:`write_bw_log` but writes an I/O completion latency
77b7e675 3068 histogram file (e.g., :file:`name_hist.x.log`) instead. Note that this
074f0817
SW
3069 file will be empty unless :option:`log_hist_msec` has also been set.
3070 See :option:`write_bw_log` for details about the filename format and
3071 `Log File Formats`_ for how data is structured within the file.
06842027 3072
f80dba8d 3073.. option:: write_iops_log=str
06842027 3074
074f0817 3075 Same as :option:`write_bw_log`, but writes an IOPS file (e.g.
15417073
SW
3076 :file:`name_iops.x.log`) instead. Because fio defaults to individual
3077 I/O logging, the value entry in the IOPS log will be 1 unless windowed
3078 logging (see :option:`log_avg_msec`) has been enabled. See
3079 :option:`write_bw_log` for details about the filename format and `Log
3080 File Formats`_ for how data is structured within the file.
06842027 3081
f80dba8d 3082.. option:: log_avg_msec=int
06842027 3083
f80dba8d
MT
3084 By default, fio will log an entry in the iops, latency, or bw log for every
3085 I/O that completes. When writing to the disk log, that can quickly grow to a
3086 very large size. Setting this option makes fio average the each log entry
3087 over the specified period of time, reducing the resolution of the log. See
3088 :option:`log_max_value` as well. Defaults to 0, logging all entries.
6fc82095 3089 Also see `Log File Formats`_.
06842027 3090
f80dba8d 3091.. option:: log_hist_msec=int
06842027 3092
f80dba8d
MT
3093 Same as :option:`log_avg_msec`, but logs entries for completion latency
3094 histograms. Computing latency percentiles from averages of intervals using
c60ebc45 3095 :option:`log_avg_msec` is inaccurate. Setting this option makes fio log
f80dba8d
MT
3096 histogram entries over the specified period of time, reducing log sizes for
3097 high IOPS devices while retaining percentile accuracy. See
074f0817
SW
3098 :option:`log_hist_coarseness` and :option:`write_hist_log` as well.
3099 Defaults to 0, meaning histogram logging is disabled.
06842027 3100
f80dba8d 3101.. option:: log_hist_coarseness=int
06842027 3102
f80dba8d
MT
3103 Integer ranging from 0 to 6, defining the coarseness of the resolution of
3104 the histogram logs enabled with :option:`log_hist_msec`. For each increment
3105 in coarseness, fio outputs half as many bins. Defaults to 0, for which
074f0817
SW
3106 histogram logs contain 1216 latency bins. See :option:`write_hist_log`
3107 and `Log File Formats`_.
8b28bd41 3108
f80dba8d 3109.. option:: log_max_value=bool
66c098b8 3110
f80dba8d
MT
3111 If :option:`log_avg_msec` is set, fio logs the average over that window. If
3112 you instead want to log the maximum value, set this option to 1. Defaults to
3113 0, meaning that averaged values are logged.
a696fa2a 3114
589e88b7 3115.. option:: log_offset=bool
a696fa2a 3116
f80dba8d 3117 If this is set, the iolog options will include the byte offset for the I/O
5a83478f
SW
3118 entry as well as the other data values. Defaults to 0 meaning that
3119 offsets are not present in logs. Also see `Log File Formats`_.
71bfa161 3120
f80dba8d 3121.. option:: log_compression=int
7de87099 3122
f80dba8d
MT
3123 If this is set, fio will compress the I/O logs as it goes, to keep the
3124 memory footprint lower. When a log reaches the specified size, that chunk is
3125 removed and compressed in the background. Given that I/O logs are fairly
3126 highly compressible, this yields a nice memory savings for longer runs. The
3127 downside is that the compression will consume some background CPU cycles, so
3128 it may impact the run. This, however, is also true if the logging ends up
3129 consuming most of the system memory. So pick your poison. The I/O logs are
3130 saved normally at the end of a run, by decompressing the chunks and storing
3131 them in the specified log file. This feature depends on the availability of
3132 zlib.
e0b0d892 3133
f80dba8d 3134.. option:: log_compression_cpus=str
e0b0d892 3135
f80dba8d
MT
3136 Define the set of CPUs that are allowed to handle online log compression for
3137 the I/O jobs. This can provide better isolation between performance
0cf90a62
SW
3138 sensitive jobs, and background compression work. See
3139 :option:`cpus_allowed` for the format used.
9e684a49 3140
f80dba8d 3141.. option:: log_store_compressed=bool
9e684a49 3142
f80dba8d
MT
3143 If set, fio will store the log files in a compressed format. They can be
3144 decompressed with fio, using the :option:`--inflate-log` command line
3145 parameter. The files will be stored with a :file:`.fz` suffix.
9e684a49 3146
f80dba8d 3147.. option:: log_unix_epoch=bool
9e684a49 3148
f80dba8d
MT
3149 If set, fio will log Unix timestamps to the log files produced by enabling
3150 write_type_log for each log type, instead of the default zero-based
3151 timestamps.
3152
3153.. option:: block_error_percentiles=bool
3154
3155 If set, record errors in trim block-sized units from writes and trims and
3156 output a histogram of how many trims it took to get to errors, and what kind
3157 of error was encountered.
3158
3159.. option:: bwavgtime=int
3160
3161 Average the calculated bandwidth over the given time. Value is specified in
3162 milliseconds. If the job also does bandwidth logging through
3163 :option:`write_bw_log`, then the minimum of this option and
3164 :option:`log_avg_msec` will be used. Default: 500ms.
3165
3166.. option:: iopsavgtime=int
3167
3168 Average the calculated IOPS over the given time. Value is specified in
3169 milliseconds. If the job also does IOPS logging through
3170 :option:`write_iops_log`, then the minimum of this option and
3171 :option:`log_avg_msec` will be used. Default: 500ms.
3172
3173.. option:: disk_util=bool
3174
3175 Generate disk utilization statistics, if the platform supports it.
3176 Default: true.
3177
3178.. option:: disable_lat=bool
3179
3180 Disable measurements of total latency numbers. Useful only for cutting back
3181 the number of calls to :manpage:`gettimeofday(2)`, as that does impact
3182 performance at really high IOPS rates. Note that to really get rid of a
3183 large amount of these calls, this option must be used with
f75ede1d 3184 :option:`disable_slat` and :option:`disable_bw_measurement` as well.
f80dba8d
MT
3185
3186.. option:: disable_clat=bool
3187
3188 Disable measurements of completion latency numbers. See
3189 :option:`disable_lat`.
3190
3191.. option:: disable_slat=bool
3192
3193 Disable measurements of submission latency numbers. See
f50fbdda 3194 :option:`disable_lat`.
f80dba8d 3195
f75ede1d 3196.. option:: disable_bw_measurement=bool, disable_bw=bool
f80dba8d
MT
3197
3198 Disable measurements of throughput/bandwidth numbers. See
3199 :option:`disable_lat`.
3200
3201.. option:: clat_percentiles=bool
3202
b599759b
JA
3203 Enable the reporting of percentiles of completion latencies. This
3204 option is mutually exclusive with :option:`lat_percentiles`.
3205
3206.. option:: lat_percentiles=bool
3207
b71968b1 3208 Enable the reporting of percentiles of I/O latencies. This is similar
b599759b
JA
3209 to :option:`clat_percentiles`, except that this includes the
3210 submission latency. This option is mutually exclusive with
3211 :option:`clat_percentiles`.
f80dba8d
MT
3212
3213.. option:: percentile_list=float_list
3214
c32ba107
JA
3215 Overwrite the default list of percentiles for completion latencies and
3216 the block error histogram. Each number is a floating number in the
3217 range (0,100], and the maximum length of the list is 20. Use ``:`` to
3218 separate the numbers, and list the numbers in ascending order. For
3219 example, ``--percentile_list=99.5:99.9`` will cause fio to report the
3220 values of completion latency below which 99.5% and 99.9% of the observed
3221 latencies fell, respectively.
f80dba8d 3222
e883cb35
JF
3223.. option:: significant_figures=int
3224
c32ba107
JA
3225 If using :option:`--output-format` of `normal`, set the significant
3226 figures to this value. Higher values will yield more precise IOPS and
3227 throughput units, while lower values will round. Requires a minimum
3228 value of 1 and a maximum value of 10. Defaults to 4.
e883cb35 3229
f80dba8d
MT
3230
3231Error handling
3232~~~~~~~~~~~~~~
3233
3234.. option:: exitall_on_error
3235
3236 When one job finishes in error, terminate the rest. The default is to wait
3237 for each job to finish.
3238
3239.. option:: continue_on_error=str
3240
3241 Normally fio will exit the job on the first observed failure. If this option
3242 is set, fio will continue the job when there is a 'non-fatal error' (EIO or
3243 EILSEQ) until the runtime is exceeded or the I/O size specified is
3244 completed. If this option is used, there are two more stats that are
3245 appended, the total error count and the first error. The error field given
3246 in the stats is the first error that was hit during the run.
3247
3248 The allowed values are:
3249
3250 **none**
3251 Exit on any I/O or verify errors.
3252
3253 **read**
3254 Continue on read errors, exit on all others.
3255
3256 **write**
3257 Continue on write errors, exit on all others.
3258
3259 **io**
3260 Continue on any I/O error, exit on all others.
3261
3262 **verify**
3263 Continue on verify errors, exit on all others.
3264
3265 **all**
3266 Continue on all errors.
3267
3268 **0**
3269 Backward-compatible alias for 'none'.
3270
3271 **1**
3272 Backward-compatible alias for 'all'.
3273
3274.. option:: ignore_error=str
3275
3276 Sometimes you want to ignore some errors during test in that case you can
a35ef7cb
TK
3277 specify error list for each error type, instead of only being able to
3278 ignore the default 'non-fatal error' using :option:`continue_on_error`.
f80dba8d
MT
3279 ``ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST`` errors for
3280 given error type is separated with ':'. Error may be symbol ('ENOSPC',
3281 'ENOMEM') or integer. Example::
3282
3283 ignore_error=EAGAIN,ENOSPC:122
3284
3285 This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from
a35ef7cb
TK
3286 WRITE. This option works by overriding :option:`continue_on_error` with
3287 the list of errors for each error type if any.
f80dba8d
MT
3288
3289.. option:: error_dump=bool
3290
3291 If set dump every error even if it is non fatal, true by default. If
3292 disabled only fatal error will be dumped.
3293
f75ede1d
SW
3294Running predefined workloads
3295----------------------------
3296
3297Fio includes predefined profiles that mimic the I/O workloads generated by
3298other tools.
3299
3300.. option:: profile=str
3301
3302 The predefined workload to run. Current profiles are:
3303
3304 **tiobench**
3305 Threaded I/O bench (tiotest/tiobench) like workload.
3306
3307 **act**
3308 Aerospike Certification Tool (ACT) like workload.
3309
3310To view a profile's additional options use :option:`--cmdhelp` after specifying
3311the profile. For example::
3312
f50fbdda 3313 $ fio --profile=act --cmdhelp
f75ede1d
SW
3314
3315Act profile options
3316~~~~~~~~~~~~~~~~~~~
3317
3318.. option:: device-names=str
3319 :noindex:
3320
3321 Devices to use.
3322
3323.. option:: load=int
3324 :noindex:
3325
3326 ACT load multiplier. Default: 1.
3327
3328.. option:: test-duration=time
3329 :noindex:
3330
947e0fe0
SW
3331 How long the entire test takes to run. When the unit is omitted, the value
3332 is given in seconds. Default: 24h.
f75ede1d
SW
3333
3334.. option:: threads-per-queue=int
3335 :noindex:
3336
f50fbdda 3337 Number of read I/O threads per device. Default: 8.
f75ede1d
SW
3338
3339.. option:: read-req-num-512-blocks=int
3340 :noindex:
3341
3342 Number of 512B blocks to read at the time. Default: 3.
3343
3344.. option:: large-block-op-kbytes=int
3345 :noindex:
3346
3347 Size of large block ops in KiB (writes). Default: 131072.
3348
3349.. option:: prep
3350 :noindex:
3351
3352 Set to run ACT prep phase.
3353
3354Tiobench profile options
3355~~~~~~~~~~~~~~~~~~~~~~~~
3356
3357.. option:: size=str
3358 :noindex:
3359
f50fbdda 3360 Size in MiB.
f75ede1d
SW
3361
3362.. option:: block=int
3363 :noindex:
3364
3365 Block size in bytes. Default: 4096.
3366
3367.. option:: numruns=int
3368 :noindex:
3369
3370 Number of runs.
3371
3372.. option:: dir=str
3373 :noindex:
3374
3375 Test directory.
3376
3377.. option:: threads=int
3378 :noindex:
3379
3380 Number of threads.
f80dba8d
MT
3381
3382Interpreting the output
3383-----------------------
3384
36214730
SW
3385..
3386 Example output was based on the following:
3387 TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --time_based \
3388 --rate=1256k --bs=14K --name=quick --runtime=1s --name=mixed \
3389 --runtime=2m --rw=rw
3390
f80dba8d
MT
3391Fio spits out a lot of output. While running, fio will display the status of the
3392jobs created. An example of that would be::
3393
9d25d068 3394 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 3395
36214730
SW
3396The characters inside the first set of square brackets denote the current status of
3397each thread. The first character is the first job defined in the job file, and so
3398forth. The possible values (in typical life cycle order) are:
f80dba8d
MT
3399
3400+------+-----+-----------------------------------------------------------+
3401| Idle | Run | |
3402+======+=====+===========================================================+
3403| P | | Thread setup, but not started. |
3404+------+-----+-----------------------------------------------------------+
3405| C | | Thread created. |
3406+------+-----+-----------------------------------------------------------+
3407| I | | Thread initialized, waiting or generating necessary data. |
3408+------+-----+-----------------------------------------------------------+
3409| | p | Thread running pre-reading file(s). |
3410+------+-----+-----------------------------------------------------------+
36214730
SW
3411| | / | Thread is in ramp period. |
3412+------+-----+-----------------------------------------------------------+
f80dba8d
MT
3413| | R | Running, doing sequential reads. |
3414+------+-----+-----------------------------------------------------------+
3415| | r | Running, doing random reads. |
3416+------+-----+-----------------------------------------------------------+
3417| | W | Running, doing sequential writes. |
3418+------+-----+-----------------------------------------------------------+
3419| | w | Running, doing random writes. |
3420+------+-----+-----------------------------------------------------------+
3421| | M | Running, doing mixed sequential reads/writes. |
3422+------+-----+-----------------------------------------------------------+
3423| | m | Running, doing mixed random reads/writes. |
3424+------+-----+-----------------------------------------------------------+
36214730
SW
3425| | D | Running, doing sequential trims. |
3426+------+-----+-----------------------------------------------------------+
3427| | d | Running, doing random trims. |
3428+------+-----+-----------------------------------------------------------+
3429| | F | Running, currently waiting for :manpage:`fsync(2)`. |
f80dba8d
MT
3430+------+-----+-----------------------------------------------------------+
3431| | V | Running, doing verification of written data. |
3432+------+-----+-----------------------------------------------------------+
36214730
SW
3433| f | | Thread finishing. |
3434+------+-----+-----------------------------------------------------------+
f80dba8d
MT
3435| E | | Thread exited, not reaped by main thread yet. |
3436+------+-----+-----------------------------------------------------------+
36214730 3437| _ | | Thread reaped. |
f80dba8d
MT
3438+------+-----+-----------------------------------------------------------+
3439| X | | Thread reaped, exited with an error. |
3440+------+-----+-----------------------------------------------------------+
3441| K | | Thread reaped, exited due to signal. |
3442+------+-----+-----------------------------------------------------------+
3443
36214730
SW
3444..
3445 Example output was based on the following:
3446 TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --runtime=58m \
3447 --time_based --rate=2512k --bs=256K --numjobs=10 \
3448 --name=readers --rw=read --name=writers --rw=write
3449
f80dba8d 3450Fio will condense the thread string as not to take up more space on the command
36214730 3451line than needed. For instance, if you have 10 readers and 10 writers running,
f80dba8d
MT
3452the output would look like this::
3453
9d25d068 3454 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 3455
36214730
SW
3456Note that the status string is displayed in order, so it's possible to tell which of
3457the jobs are currently doing what. In the example above this means that jobs 1--10
3458are readers and 11--20 are writers.
f80dba8d
MT
3459
3460The other values are fairly self explanatory -- number of threads currently
36214730
SW
3461running and doing I/O, the number of currently open files (f=), the estimated
3462completion percentage, the rate of I/O since last check (read speed listed first,
f50fbdda
TK
3463then write speed and optionally trim speed) in terms of bandwidth and IOPS,
3464and time to completion for the current running group. It's impossible to estimate
3465runtime of the following groups (if any).
36214730
SW
3466
3467..
3468 Example output was based on the following:
3469 TZ=UTC fio --iodepth=16 --ioengine=posixaio --filename=/tmp/fiofile \
3470 --direct=1 --size=100M --time_based --runtime=50s --rate_iops=89 \
3471 --bs=7K --name=Client1 --rw=write
3472
3473When fio is done (or interrupted by :kbd:`Ctrl-C`), it will show the data for
3474each thread, group of threads, and disks in that order. For each overall thread (or
3475group) the output looks like::
3476
3477 Client1: (groupid=0, jobs=1): err= 0: pid=16109: Sat Jun 24 12:07:54 2017
3478 write: IOPS=88, BW=623KiB/s (638kB/s)(30.4MiB/50032msec)
3479 slat (nsec): min=500, max=145500, avg=8318.00, stdev=4781.50
3480 clat (usec): min=170, max=78367, avg=4019.02, stdev=8293.31
3481 lat (usec): min=174, max=78375, avg=4027.34, stdev=8291.79
3482 clat percentiles (usec):
3483 | 1.00th=[ 302], 5.00th=[ 326], 10.00th=[ 343], 20.00th=[ 363],
3484 | 30.00th=[ 392], 40.00th=[ 404], 50.00th=[ 416], 60.00th=[ 445],
3485 | 70.00th=[ 816], 80.00th=[ 6718], 90.00th=[12911], 95.00th=[21627],
3486 | 99.00th=[43779], 99.50th=[51643], 99.90th=[68682], 99.95th=[72877],
3487 | 99.99th=[78119]
3488 bw ( KiB/s): min= 532, max= 686, per=0.10%, avg=622.87, stdev=24.82, samples= 100
3489 iops : min= 76, max= 98, avg=88.98, stdev= 3.54, samples= 100
29092211
VF
3490 lat (usec) : 250=0.04%, 500=64.11%, 750=4.81%, 1000=2.79%
3491 lat (msec) : 2=4.16%, 4=1.84%, 10=4.90%, 20=11.33%, 50=5.37%
3492 lat (msec) : 100=0.65%
36214730
SW
3493 cpu : usr=0.27%, sys=0.18%, ctx=12072, majf=0, minf=21
3494 IO depths : 1=85.0%, 2=13.1%, 4=1.8%, 8=0.1%, 16=0.0%, 32=0.0%, >=64=0.0%
3495 submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
3496 complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
3497 issued rwt: total=0,4450,0, short=0,0,0, dropped=0,0,0
3498 latency : target=0, window=0, percentile=100.00%, depth=8
3499
3500The job name (or first job's name when using :option:`group_reporting`) is printed,
3501along with the group id, count of jobs being aggregated, last error id seen (which
3502is 0 when there are no errors), pid/tid of that thread and the time the job/group
3503completed. Below are the I/O statistics for each data direction performed (showing
3504writes in the example above). In the order listed, they denote:
3505
3506**read/write/trim**
3507 The string before the colon shows the I/O direction the statistics
3508 are for. **IOPS** is the average I/Os performed per second. **BW**
3509 is the average bandwidth rate shown as: value in power of 2 format
3510 (value in power of 10 format). The last two values show: (**total
3511 I/O performed** in power of 2 format / **runtime** of that thread).
f80dba8d
MT
3512
3513**slat**
36214730
SW
3514 Submission latency (**min** being the minimum, **max** being the
3515 maximum, **avg** being the average, **stdev** being the standard
3516 deviation). This is the time it took to submit the I/O. For
3517 sync I/O this row is not displayed as the slat is really the
3518 completion latency (since queue/complete is one operation there).
3519 This value can be in nanoseconds, microseconds or milliseconds ---
3520 fio will choose the most appropriate base and print that (in the
3521 example above nanoseconds was the best scale). Note: in :option:`--minimal` mode
0d237712 3522 latencies are always expressed in microseconds.
f80dba8d
MT
3523
3524**clat**
3525 Completion latency. Same names as slat, this denotes the time from
3526 submission to completion of the I/O pieces. For sync I/O, clat will
3527 usually be equal (or very close) to 0, as the time from submit to
3528 complete is basically just CPU time (I/O has already been done, see slat
3529 explanation).
3530
29092211
VF
3531**lat**
3532 Total latency. Same names as slat and clat, this denotes the time from
3533 when fio created the I/O unit to completion of the I/O operation.
3534
f80dba8d 3535**bw**
36214730
SW
3536 Bandwidth statistics based on samples. Same names as the xlat stats,
3537 but also includes the number of samples taken (**samples**) and an
3538 approximate percentage of total aggregate bandwidth this thread
3539 received in its group (**per**). This last value is only really
3540 useful if the threads in this group are on the same disk, since they
3541 are then competing for disk access.
3542
3543**iops**
3544 IOPS statistics based on samples. Same names as bw.
f80dba8d 3545
29092211
VF
3546**lat (nsec/usec/msec)**
3547 The distribution of I/O completion latencies. This is the time from when
3548 I/O leaves fio and when it gets completed. Unlike the separate
3549 read/write/trim sections above, the data here and in the remaining
3550 sections apply to all I/Os for the reporting group. 250=0.04% means that
3551 0.04% of the I/Os completed in under 250us. 500=64.11% means that 64.11%
3552 of the I/Os required 250 to 499us for completion.
3553
f80dba8d
MT
3554**cpu**
3555 CPU usage. User and system time, along with the number of context
3556 switches this thread went through, usage of system and user time, and
3557 finally the number of major and minor page faults. The CPU utilization
3558 numbers are averages for the jobs in that reporting group, while the
23a8e176 3559 context and fault counters are summed.
f80dba8d
MT
3560
3561**IO depths**
a2140525
SW
3562 The distribution of I/O depths over the job lifetime. The numbers are
3563 divided into powers of 2 and each entry covers depths from that value
3564 up to those that are lower than the next entry -- e.g., 16= covers
3565 depths from 16 to 31. Note that the range covered by a depth
3566 distribution entry can be different to the range covered by the
3567 equivalent submit/complete distribution entry.
f80dba8d
MT
3568
3569**IO submit**
3570 How many pieces of I/O were submitting in a single submit call. Each
c60ebc45 3571 entry denotes that amount and below, until the previous entry -- e.g.,
a2140525
SW
3572 16=100% means that we submitted anywhere between 9 to 16 I/Os per submit
3573 call. Note that the range covered by a submit distribution entry can
3574 be different to the range covered by the equivalent depth distribution
3575 entry.
f80dba8d
MT
3576
3577**IO complete**
3578 Like the above submit number, but for completions instead.
3579
36214730
SW
3580**IO issued rwt**
3581 The number of read/write/trim requests issued, and how many of them were
3582 short or dropped.
f80dba8d 3583
29092211 3584**IO latency**
ee21ebee 3585 These values are for :option:`latency_target` and related options. When
29092211
VF
3586 these options are engaged, this section describes the I/O depth required
3587 to meet the specified latency target.
71bfa161 3588
36214730
SW
3589..
3590 Example output was based on the following:
3591 TZ=UTC fio --ioengine=null --iodepth=2 --size=100M --numjobs=2 \
3592 --rate_process=poisson --io_limit=32M --name=read --bs=128k \
3593 --rate=11M --name=write --rw=write --bs=2k --rate=700k
3594
71bfa161 3595After each client has been listed, the group statistics are printed. They
f80dba8d 3596will look like this::
71bfa161 3597
f80dba8d 3598 Run status group 0 (all jobs):
36214730
SW
3599 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
3600 WRITE: bw=1231KiB/s (1261kB/s), 616KiB/s-621KiB/s (630kB/s-636kB/s), io=64.0MiB (67.1MB), run=52747-53223msec
71bfa161 3601
36214730 3602For each data direction it prints:
71bfa161 3603
36214730
SW
3604**bw**
3605 Aggregate bandwidth of threads in this group followed by the
3606 minimum and maximum bandwidth of all the threads in this group.
3607 Values outside of brackets are power-of-2 format and those
3608 within are the equivalent value in a power-of-10 format.
f80dba8d 3609**io**
36214730
SW
3610 Aggregate I/O performed of all threads in this group. The
3611 format is the same as bw.
3612**run**
3613 The smallest and longest runtimes of the threads in this group.
71bfa161 3614
f50fbdda 3615And finally, the disk statistics are printed. This is Linux specific. They will look like this::
71bfa161 3616
f80dba8d
MT
3617 Disk stats (read/write):
3618 sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00%
71bfa161
JA
3619
3620Each value is printed for both reads and writes, with reads first. The
3621numbers denote:
3622
f80dba8d 3623**ios**
c60ebc45 3624 Number of I/Os performed by all groups.
f80dba8d 3625**merge**
007c7be9 3626 Number of merges performed by the I/O scheduler.
f80dba8d
MT
3627**ticks**
3628 Number of ticks we kept the disk busy.
36214730 3629**in_queue**
f80dba8d
MT
3630 Total time spent in the disk queue.
3631**util**
3632 The disk utilization. A value of 100% means we kept the disk
71bfa161
JA
3633 busy constantly, 50% would be a disk idling half of the time.
3634
f80dba8d
MT
3635It is also possible to get fio to dump the current output while it is running,
3636without terminating the job. To do that, send fio the **USR1** signal. You can
3637also get regularly timed dumps by using the :option:`--status-interval`
3638parameter, or by creating a file in :file:`/tmp` named
3639:file:`fio-dump-status`. If fio sees this file, it will unlink it and dump the
3640current output status.
8423bd11 3641
71bfa161 3642
f80dba8d
MT
3643Terse output
3644------------
71bfa161 3645
f80dba8d
MT
3646For scripted usage where you typically want to generate tables or graphs of the
3647results, fio can output the results in a semicolon separated format. The format
3648is one long line of values, such as::
71bfa161 3649
f80dba8d
MT
3650 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%
3651 A description of this job goes here.
562c2d2f
DN
3652
3653The job description (if provided) follows on a second line.
71bfa161 3654
a7f77fa6
SW
3655To enable terse output, use the :option:`--minimal` or
3656:option:`--output-format`\=terse command line options. The
f80dba8d
MT
3657first value is the version of the terse output format. If the output has to be
3658changed for some reason, this number will be incremented by 1 to signify that
3659change.
6820cb3b 3660
a2c95580 3661Split up, the format is as follows (comments in brackets denote when a
007c7be9 3662field was introduced or whether it's specific to some terse version):
71bfa161 3663
f80dba8d
MT
3664 ::
3665
f50fbdda 3666 terse version, fio version [v3], jobname, groupid, error
f80dba8d
MT
3667
3668 READ status::
3669
3670 Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
3671 Submission latency: min, max, mean, stdev (usec)
3672 Completion latency: min, max, mean, stdev (usec)
3673 Completion latency percentiles: 20 fields (see below)
3674 Total latency: min, max, mean, stdev (usec)
f50fbdda
TK
3675 Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
3676 IOPS [v5]: min, max, mean, stdev, number of samples
f80dba8d
MT
3677
3678 WRITE status:
3679
3680 ::
3681
3682 Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
3683 Submission latency: min, max, mean, stdev (usec)
247823cc 3684 Completion latency: min, max, mean, stdev (usec)
f80dba8d
MT
3685 Completion latency percentiles: 20 fields (see below)
3686 Total latency: min, max, mean, stdev (usec)
f50fbdda
TK
3687 Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
3688 IOPS [v5]: min, max, mean, stdev, number of samples
a2c95580
AH
3689
3690 TRIM status [all but version 3]:
3691
f50fbdda 3692 Fields are similar to READ/WRITE status.
f80dba8d
MT
3693
3694 CPU usage::
3695
3696 user, system, context switches, major faults, minor faults
3697
3698 I/O depths::
3699
3700 <=1, 2, 4, 8, 16, 32, >=64
3701
3702 I/O latencies microseconds::
3703
3704 <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
3705
3706 I/O latencies milliseconds::
3707
3708 <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
3709
a2c95580 3710 Disk utilization [v3]::
f80dba8d 3711
f50fbdda
TK
3712 disk name, read ios, write ios, read merges, write merges, read ticks, write ticks,
3713 time spent in queue, disk utilization percentage
f80dba8d
MT
3714
3715 Additional Info (dependent on continue_on_error, default off)::
3716
3717 total # errors, first error code
3718
3719 Additional Info (dependent on description being set)::
3720
3721 Text description
3722
3723Completion latency percentiles can be a grouping of up to 20 sets, so for the
3724terse output fio writes all of them. Each field will look like this::
1db92cb6 3725
f50fbdda 3726 1.00%=6112
1db92cb6 3727
f80dba8d 3728which is the Xth percentile, and the `usec` latency associated with it.
1db92cb6 3729
f50fbdda 3730For `Disk utilization`, all disks used by fio are shown. So for each disk there
f80dba8d 3731will be a disk utilization section.
f2f788dd 3732
2fc26c3d 3733Below is a single line containing short names for each of the fields in the
2831be97 3734minimal output v3, separated by semicolons::
2fc26c3d 3735
f50fbdda 3736 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 3737
25c8b9d7 3738
44c82dba
VF
3739JSON output
3740------------
3741
3742The `json` output format is intended to be both human readable and convenient
3743for automated parsing. For the most part its sections mirror those of the
3744`normal` output. The `runtime` value is reported in msec and the `bw` value is
3745reported in 1024 bytes per second units.
3746
3747
d29c4a91
VF
3748JSON+ output
3749------------
3750
3751The `json+` output format is identical to the `json` output format except that it
3752adds a full dump of the completion latency bins. Each `bins` object contains a
3753set of (key, value) pairs where keys are latency durations and values count how
3754many I/Os had completion latencies of the corresponding duration. For example,
3755consider:
3756
3757 "bins" : { "87552" : 1, "89600" : 1, "94720" : 1, "96768" : 1, "97792" : 1, "99840" : 1, "100864" : 2, "103936" : 6, "104960" : 534, "105984" : 5995, "107008" : 7529, ... }
3758
3759This data indicates that one I/O required 87,552ns to complete, two I/Os required
3760100,864ns to complete, and 7529 I/Os required 107,008ns to complete.
3761
3762Also included with fio is a Python script `fio_jsonplus_clat2csv` that takes
3763json+ output and generates CSV-formatted latency data suitable for plotting.
3764
3765The latency durations actually represent the midpoints of latency intervals.
f50fbdda 3766For details refer to :file:`stat.h`.
d29c4a91
VF
3767
3768
f80dba8d
MT
3769Trace file format
3770-----------------
3771
3772There are two trace file format that you can encounter. The older (v1) format is
3773unsupported since version 1.20-rc3 (March 2008). It will still be described
25c8b9d7
PD
3774below in case that you get an old trace and want to understand it.
3775
3776In any case the trace is a simple text file with a single action per line.
3777
3778
f80dba8d
MT
3779Trace file format v1
3780~~~~~~~~~~~~~~~~~~~~
3781
3782Each line represents a single I/O action in the following format::
3783
3784 rw, offset, length
25c8b9d7 3785
f50fbdda 3786where `rw=0/1` for read/write, and the `offset` and `length` entries being in bytes.
25c8b9d7 3787
22413915 3788This format is not supported in fio versions >= 1.20-rc3.
25c8b9d7 3789
25c8b9d7 3790
f80dba8d
MT
3791Trace file format v2
3792~~~~~~~~~~~~~~~~~~~~
25c8b9d7 3793
f80dba8d
MT
3794The second version of the trace file format was added in fio version 1.17. It
3795allows to access more then one file per trace and has a bigger set of possible