doc: improve readonly option description
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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,
197 `time` is interpreted in seconds.
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198
199.. option:: --section=name
200
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201 Only run specified section `name` in job file. Multiple sections can be specified.
202 The ``--section`` option allows one to combine related jobs into one file.
203 E.g. one job file could define light, moderate, and heavy sections. Tell
204 fio to run only the "heavy" section by giving ``--section=heavy``
205 command line option. One can also specify the "write" operations in one
206 section and "verify" operation in another section. The ``--section`` option
207 only applies to job sections. The reserved *global* section is always
208 parsed and used.
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209
210.. option:: --alloc-size=kb
211
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212 Set the internal smalloc pool size to `kb` in KiB. The
213 ``--alloc-size`` switch allows one to use a larger pool size for smalloc.
214 If running large jobs with randommap enabled, fio can run out of memory.
215 Smalloc is an internal allocator for shared structures from a fixed size
216 memory pool and can grow to 16 pools. The pool size defaults to 16MiB.
f80dba8d 217
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218 NOTE: While running :file:`.fio_smalloc.*` backing store files are visible
219 in :file:`/tmp`.
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220
221.. option:: --warnings-fatal
222
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223 All fio parser warnings are fatal, causing fio to exit with an
224 error.
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225
226.. option:: --max-jobs=nr
227
f50fbdda 228 Set the maximum number of threads/processes to support to `nr`.
818322cc 229 NOTE: On Linux, it may be necessary to increase the shared-memory
71aa48eb 230 limit (:file:`/proc/sys/kernel/shmmax`) if fio runs into errors while
818322cc 231 creating jobs.
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232
233.. option:: --server=args
234
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235 Start a backend server, with `args` specifying what to listen to.
236 See `Client/Server`_ section.
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237
238.. option:: --daemonize=pidfile
239
b034c0dd 240 Background a fio server, writing the pid to the given `pidfile` file.
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241
242.. option:: --client=hostname
243
f50fbdda 244 Instead of running the jobs locally, send and run them on the given `hostname`
71aa48eb 245 or set of `hostname`\s. See `Client/Server`_ section.
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246
247.. option:: --remote-config=file
248
f50fbdda 249 Tell fio server to load this local `file`.
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250
251.. option:: --idle-prof=option
252
b8f7e412 253 Report CPU idleness. `option` is one of the following:
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254
255 **calibrate**
256 Run unit work calibration only and exit.
257
258 **system**
259 Show aggregate system idleness and unit work.
260
261 **percpu**
262 As **system** but also show per CPU idleness.
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263
264.. option:: --inflate-log=log
265
f50fbdda 266 Inflate and output compressed `log`.
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267
268.. option:: --trigger-file=file
269
f50fbdda 270 Execute trigger command when `file` exists.
f80dba8d 271
f50fbdda 272.. option:: --trigger-timeout=time
f80dba8d 273
f50fbdda 274 Execute trigger at this `time`.
f80dba8d 275
f50fbdda 276.. option:: --trigger=command
f80dba8d 277
f50fbdda 278 Set this `command` as local trigger.
f80dba8d 279
f50fbdda 280.. option:: --trigger-remote=command
f80dba8d 281
f50fbdda 282 Set this `command` as remote trigger.
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283
284.. option:: --aux-path=path
285
f50fbdda 286 Use this `path` for fio state generated files.
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287
288Any parameters following the options will be assumed to be job files, unless
289they match a job file parameter. Multiple job files can be listed and each job
290file will be regarded as a separate group. Fio will :option:`stonewall`
291execution between each group.
292
293
294Job file format
295---------------
296
297As previously described, fio accepts one or more job files describing what it is
298supposed to do. The job file format is the classic ini file, where the names
c60ebc45 299enclosed in [] brackets define the job name. You are free to use any ASCII name
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300you want, except *global* which has special meaning. Following the job name is
301a sequence of zero or more parameters, one per line, that define the behavior of
302the job. If the first character in a line is a ';' or a '#', the entire line is
303discarded as a comment.
304
305A *global* section sets defaults for the jobs described in that file. A job may
306override a *global* section parameter, and a job file may even have several
307*global* sections if so desired. A job is only affected by a *global* section
308residing above it.
309
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310The :option:`--cmdhelp` option also lists all options. If used with a `command`
311argument, :option:`--cmdhelp` will detail the given `command`.
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312
313See the `examples/` directory for inspiration on how to write job files. Note
314the copyright and license requirements currently apply to `examples/` files.
315
316So let's look at a really simple job file that defines two processes, each
317randomly reading from a 128MiB file:
318
319.. code-block:: ini
320
321 ; -- start job file --
322 [global]
323 rw=randread
324 size=128m
325
326 [job1]
327
328 [job2]
329
330 ; -- end job file --
331
332As you can see, the job file sections themselves are empty as all the described
333parameters are shared. As no :option:`filename` option is given, fio makes up a
334`filename` for each of the jobs as it sees fit. On the command line, this job
335would look as follows::
336
337$ fio --name=global --rw=randread --size=128m --name=job1 --name=job2
338
339
340Let's look at an example that has a number of processes writing randomly to
341files:
342
343.. code-block:: ini
344
345 ; -- start job file --
346 [random-writers]
347 ioengine=libaio
348 iodepth=4
349 rw=randwrite
350 bs=32k
351 direct=0
352 size=64m
353 numjobs=4
354 ; -- end job file --
355
356Here we have no *global* section, as we only have one job defined anyway. We
357want to use async I/O here, with a depth of 4 for each file. We also increased
358the buffer size used to 32KiB and define numjobs to 4 to fork 4 identical
359jobs. The result is 4 processes each randomly writing to their own 64MiB
360file. Instead of using the above job file, you could have given the parameters
361on the command line. For this case, you would specify::
362
363$ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4
364
365When fio is utilized as a basis of any reasonably large test suite, it might be
366desirable to share a set of standardized settings across multiple job files.
367Instead of copy/pasting such settings, any section may pull in an external
368:file:`filename.fio` file with *include filename* directive, as in the following
369example::
370
371 ; -- start job file including.fio --
372 [global]
373 filename=/tmp/test
374 filesize=1m
375 include glob-include.fio
376
377 [test]
378 rw=randread
379 bs=4k
380 time_based=1
381 runtime=10
382 include test-include.fio
383 ; -- end job file including.fio --
384
385.. code-block:: ini
386
387 ; -- start job file glob-include.fio --
388 thread=1
389 group_reporting=1
390 ; -- end job file glob-include.fio --
391
392.. code-block:: ini
393
394 ; -- start job file test-include.fio --
395 ioengine=libaio
396 iodepth=4
397 ; -- end job file test-include.fio --
398
399Settings pulled into a section apply to that section only (except *global*
400section). Include directives may be nested in that any included file may contain
401further include directive(s). Include files may not contain [] sections.
402
403
404Environment variables
405~~~~~~~~~~~~~~~~~~~~~
406
407Fio also supports environment variable expansion in job files. Any sub-string of
408the form ``${VARNAME}`` as part of an option value (in other words, on the right
409of the '='), will be expanded to the value of the environment variable called
410`VARNAME`. If no such environment variable is defined, or `VARNAME` is the
411empty string, the empty string will be substituted.
412
413As an example, let's look at a sample fio invocation and job file::
414
415$ SIZE=64m NUMJOBS=4 fio jobfile.fio
416
417.. code-block:: ini
418
419 ; -- start job file --
420 [random-writers]
421 rw=randwrite
422 size=${SIZE}
423 numjobs=${NUMJOBS}
424 ; -- end job file --
425
426This will expand to the following equivalent job file at runtime:
427
428.. code-block:: ini
429
430 ; -- start job file --
431 [random-writers]
432 rw=randwrite
433 size=64m
434 numjobs=4
435 ; -- end job file --
436
437Fio ships with a few example job files, you can also look there for inspiration.
438
439Reserved keywords
440~~~~~~~~~~~~~~~~~
441
442Additionally, fio has a set of reserved keywords that will be replaced
443internally with the appropriate value. Those keywords are:
444
445**$pagesize**
446
447 The architecture page size of the running system.
448
449**$mb_memory**
450
451 Megabytes of total memory in the system.
452
453**$ncpus**
454
455 Number of online available CPUs.
456
457These can be used on the command line or in the job file, and will be
458automatically substituted with the current system values when the job is
459run. Simple math is also supported on these keywords, so you can perform actions
460like::
461
b034c0dd 462 size=8*$mb_memory
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463
464and get that properly expanded to 8 times the size of memory in the machine.
465
466
467Job file parameters
468-------------------
469
470This section describes in details each parameter associated with a job. Some
471parameters take an option of a given type, such as an integer or a
472string. Anywhere a numeric value is required, an arithmetic expression may be
473used, provided it is surrounded by parentheses. Supported operators are:
474
475 - addition (+)
476 - subtraction (-)
477 - multiplication (*)
478 - division (/)
479 - modulus (%)
480 - exponentiation (^)
481
482For time values in expressions, units are microseconds by default. This is
483different than for time values not in expressions (not enclosed in
484parentheses). The following types are used:
485
486
487Parameter types
488~~~~~~~~~~~~~~~
489
490**str**
b034c0dd 491 String: A sequence of alphanumeric characters.
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492
493**time**
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494 Integer with possible time suffix. Without a unit value is interpreted as
495 seconds unless otherwise specified. Accepts a suffix of 'd' for days, 'h' for
496 hours, 'm' for minutes, 's' for seconds, 'ms' (or 'msec') for milliseconds and
497 'us' (or 'usec') for microseconds. For example, use 10m for 10 minutes.
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498
499.. _int:
500
501**int**
502 Integer. A whole number value, which may contain an integer prefix
503 and an integer suffix:
504
b034c0dd 505 [*integer prefix*] **number** [*integer suffix*]
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506
507 The optional *integer prefix* specifies the number's base. The default
508 is decimal. *0x* specifies hexadecimal.
509
510 The optional *integer suffix* specifies the number's units, and includes an
511 optional unit prefix and an optional unit. For quantities of data, the
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512 default unit is bytes. For quantities of time, the default unit is seconds
513 unless otherwise specified.
f80dba8d 514
9207a0cb 515 With :option:`kb_base`\=1000, fio follows international standards for unit
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516 prefixes. To specify power-of-10 decimal values defined in the
517 International System of Units (SI):
518
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519 * *K* -- means kilo (K) or 1000
520 * *M* -- means mega (M) or 1000**2
521 * *G* -- means giga (G) or 1000**3
522 * *T* -- means tera (T) or 1000**4
523 * *P* -- means peta (P) or 1000**5
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524
525 To specify power-of-2 binary values defined in IEC 80000-13:
526
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527 * *Ki* -- means kibi (Ki) or 1024
528 * *Mi* -- means mebi (Mi) or 1024**2
529 * *Gi* -- means gibi (Gi) or 1024**3
530 * *Ti* -- means tebi (Ti) or 1024**4
531 * *Pi* -- means pebi (Pi) or 1024**5
f80dba8d 532
9207a0cb 533 With :option:`kb_base`\=1024 (the default), the unit prefixes are opposite
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534 from those specified in the SI and IEC 80000-13 standards to provide
535 compatibility with old scripts. For example, 4k means 4096.
536
537 For quantities of data, an optional unit of 'B' may be included
b8f7e412 538 (e.g., 'kB' is the same as 'k').
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539
540 The *integer suffix* is not case sensitive (e.g., m/mi mean mebi/mega,
541 not milli). 'b' and 'B' both mean byte, not bit.
542
9207a0cb 543 Examples with :option:`kb_base`\=1000:
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544
545 * *4 KiB*: 4096, 4096b, 4096B, 4ki, 4kib, 4kiB, 4Ki, 4KiB
546 * *1 MiB*: 1048576, 1mi, 1024ki
547 * *1 MB*: 1000000, 1m, 1000k
548 * *1 TiB*: 1099511627776, 1ti, 1024gi, 1048576mi
549 * *1 TB*: 1000000000, 1t, 1000m, 1000000k
550
9207a0cb 551 Examples with :option:`kb_base`\=1024 (default):
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552
553 * *4 KiB*: 4096, 4096b, 4096B, 4k, 4kb, 4kB, 4K, 4KB
554 * *1 MiB*: 1048576, 1m, 1024k
555 * *1 MB*: 1000000, 1mi, 1000ki
556 * *1 TiB*: 1099511627776, 1t, 1024g, 1048576m
557 * *1 TB*: 1000000000, 1ti, 1000mi, 1000000ki
558
559 To specify times (units are not case sensitive):
560
561 * *D* -- means days
562 * *H* -- means hours
4502cb42 563 * *M* -- means minutes
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564 * *s* -- or sec means seconds (default)
565 * *ms* -- or *msec* means milliseconds
566 * *us* -- or *usec* means microseconds
567
568 If the option accepts an upper and lower range, use a colon ':' or
569 minus '-' to separate such values. See :ref:`irange <irange>`.
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570 If the lower value specified happens to be larger than the upper value
571 the two values are swapped.
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572
573.. _bool:
574
575**bool**
576 Boolean. Usually parsed as an integer, however only defined for
577 true and false (1 and 0).
578
579.. _irange:
580
581**irange**
582 Integer range with suffix. Allows value range to be given, such as
c60ebc45 583 1024-4096. A colon may also be used as the separator, e.g. 1k:4k. If the
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584 option allows two sets of ranges, they can be specified with a ',' or '/'
585 delimiter: 1k-4k/8k-32k. Also see :ref:`int <int>`.
586
587**float_list**
588 A list of floating point numbers, separated by a ':' character.
589
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590With the above in mind, here follows the complete list of fio job parameters.
591
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592
593Units
594~~~~~
595
596.. option:: kb_base=int
597
598 Select the interpretation of unit prefixes in input parameters.
599
600 **1000**
601 Inputs comply with IEC 80000-13 and the International
602 System of Units (SI). Use:
603
604 - power-of-2 values with IEC prefixes (e.g., KiB)
605 - power-of-10 values with SI prefixes (e.g., kB)
606
607 **1024**
608 Compatibility mode (default). To avoid breaking old scripts:
609
610 - power-of-2 values with SI prefixes
611 - power-of-10 values with IEC prefixes
612
613 See :option:`bs` for more details on input parameters.
614
615 Outputs always use correct prefixes. Most outputs include both
616 side-by-side, like::
617
618 bw=2383.3kB/s (2327.4KiB/s)
619
620 If only one value is reported, then kb_base selects the one to use:
621
622 **1000** -- SI prefixes
623
624 **1024** -- IEC prefixes
625
626.. option:: unit_base=int
627
628 Base unit for reporting. Allowed values are:
629
630 **0**
631 Use auto-detection (default).
632 **8**
633 Byte based.
634 **1**
635 Bit based.
636
637
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638Job description
639~~~~~~~~~~~~~~~
640
641.. option:: name=str
642
643 ASCII name of the job. This may be used to override the name printed by fio
644 for this job. Otherwise the job name is used. On the command line this
645 parameter has the special purpose of also signaling the start of a new job.
646
647.. option:: description=str
648
649 Text description of the job. Doesn't do anything except dump this text
650 description when this job is run. It's not parsed.
651
652.. option:: loops=int
653
654 Run the specified number of iterations of this job. Used to repeat the same
655 workload a given number of times. Defaults to 1.
656
657.. option:: numjobs=int
658
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659 Create the specified number of clones of this job. Each clone of job
660 is spawned as an independent thread or process. May be used to setup a
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661 larger number of threads/processes doing the same thing. Each thread is
662 reported separately; to see statistics for all clones as a whole, use
663 :option:`group_reporting` in conjunction with :option:`new_group`.
a47b697c 664 See :option:`--max-jobs`. Default: 1.
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665
666
667Time related parameters
668~~~~~~~~~~~~~~~~~~~~~~~
669
670.. option:: runtime=time
671
f75ede1d 672 Tell fio to terminate processing after the specified period of time. It
f80dba8d 673 can be quite hard to determine for how long a specified job will run, so
f75ede1d 674 this parameter is handy to cap the total runtime to a given time. When
804c0839 675 the unit is omitted, the value is interpreted in seconds.
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676
677.. option:: time_based
678
679 If set, fio will run for the duration of the :option:`runtime` specified
680 even if the file(s) are completely read or written. It will simply loop over
681 the same workload as many times as the :option:`runtime` allows.
682
a881438b 683.. option:: startdelay=irange(time)
f80dba8d 684
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685 Delay the start of job for the specified amount of time. Can be a single
686 value or a range. When given as a range, each thread will choose a value
687 randomly from within the range. Value is in seconds if a unit is omitted.
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688
689.. option:: ramp_time=time
690
691 If set, fio will run the specified workload for this amount of time before
692 logging any performance numbers. Useful for letting performance settle
693 before logging results, thus minimizing the runtime required for stable
694 results. Note that the ``ramp_time`` is considered lead in time for a job,
695 thus it will increase the total runtime if a special timeout or
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696 :option:`runtime` is specified. When the unit is omitted, the value is
697 given in seconds.
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698
699.. option:: clocksource=str
700
701 Use the given clocksource as the base of timing. The supported options are:
702
703 **gettimeofday**
704 :manpage:`gettimeofday(2)`
705
706 **clock_gettime**
707 :manpage:`clock_gettime(2)`
708
709 **cpu**
710 Internal CPU clock source
711
712 cpu is the preferred clocksource if it is reliable, as it is very fast (and
713 fio is heavy on time calls). Fio will automatically use this clocksource if
714 it's supported and considered reliable on the system it is running on,
715 unless another clocksource is specifically set. For x86/x86-64 CPUs, this
716 means supporting TSC Invariant.
717
718.. option:: gtod_reduce=bool
719
720 Enable all of the :manpage:`gettimeofday(2)` reducing options
f75ede1d 721 (:option:`disable_clat`, :option:`disable_slat`, :option:`disable_bw_measurement`) plus
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722 reduce precision of the timeout somewhat to really shrink the
723 :manpage:`gettimeofday(2)` call count. With this option enabled, we only do
724 about 0.4% of the :manpage:`gettimeofday(2)` calls we would have done if all
725 time keeping was enabled.
726
727.. option:: gtod_cpu=int
728
729 Sometimes it's cheaper to dedicate a single thread of execution to just
730 getting the current time. Fio (and databases, for instance) are very
731 intensive on :manpage:`gettimeofday(2)` calls. With this option, you can set
732 one CPU aside for doing nothing but logging current time to a shared memory
733 location. Then the other threads/processes that run I/O workloads need only
734 copy that segment, instead of entering the kernel with a
735 :manpage:`gettimeofday(2)` call. The CPU set aside for doing these time
736 calls will be excluded from other uses. Fio will manually clear it from the
737 CPU mask of other jobs.
738
739
740Target file/device
741~~~~~~~~~~~~~~~~~~
742
743.. option:: directory=str
744
745 Prefix filenames with this directory. Used to place files in a different
746 location than :file:`./`. You can specify a number of directories by
747 separating the names with a ':' character. These directories will be
02dd2689 748 assigned equally distributed to job clones created by :option:`numjobs` as
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749 long as they are using generated filenames. If specific `filename(s)` are
750 set fio will use the first listed directory, and thereby matching the
751 `filename` semantic which generates a file each clone if not specified, but
752 let all clones use the same if set.
753
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754 See the :option:`filename` option for information on how to escape "``:``" and
755 "``\``" characters within the directory path itself.
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756
757.. option:: filename=str
758
759 Fio normally makes up a `filename` based on the job name, thread number, and
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760 file number (see :option:`filename_format`). If you want to share files
761 between threads in a job or several
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762 jobs with fixed file paths, specify a `filename` for each of them to override
763 the default. If the ioengine is file based, you can specify a number of files
764 by separating the names with a ':' colon. So if you wanted a job to open
765 :file:`/dev/sda` and :file:`/dev/sdb` as the two working files, you would use
766 ``filename=/dev/sda:/dev/sdb``. This also means that whenever this option is
767 specified, :option:`nrfiles` is ignored. The size of regular files specified
02dd2689 768 by this option will be :option:`size` divided by number of files unless an
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769 explicit size is specified by :option:`filesize`.
770
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771 Each colon and backslash in the wanted path must be escaped with a ``\``
772 character. For instance, if the path is :file:`/dev/dsk/foo@3,0:c` then you
773 would use ``filename=/dev/dsk/foo@3,0\:c`` and if the path is
774 :file:`F:\\filename` then you would use ``filename=F\:\\filename``.
775
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776 On Windows, disk devices are accessed as :file:`\\\\.\\PhysicalDrive0` for
777 the first device, :file:`\\\\.\\PhysicalDrive1` for the second etc.
778 Note: Windows and FreeBSD prevent write access to areas
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779 of the disk containing in-use data (e.g. filesystems).
780
781 The filename "`-`" is a reserved name, meaning *stdin* or *stdout*. Which
782 of the two depends on the read/write direction set.
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783
784.. option:: filename_format=str
785
786 If sharing multiple files between jobs, it is usually necessary to have fio
787 generate the exact names that you want. By default, fio will name a file
788 based on the default file format specification of
789 :file:`jobname.jobnumber.filenumber`. With this option, that can be
790 customized. Fio will recognize and replace the following keywords in this
791 string:
792
793 **$jobname**
794 The name of the worker thread or process.
795 **$jobnum**
796 The incremental number of the worker thread or process.
797 **$filenum**
798 The incremental number of the file for that worker thread or
799 process.
800
801 To have dependent jobs share a set of files, this option can be set to have
802 fio generate filenames that are shared between the two. For instance, if
803 :file:`testfiles.$filenum` is specified, file number 4 for any job will be
804 named :file:`testfiles.4`. The default of :file:`$jobname.$jobnum.$filenum`
805 will be used if no other format specifier is given.
806
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807 If you specify a path then the directories will be created up to the
808 main directory for the file. So for example if you specify
809 ``filename_format=a/b/c/$jobnum`` then the directories a/b/c will be
810 created before the file setup part of the job. If you specify
811 :option:`directory` then the path will be relative that directory,
812 otherwise it is treated as the absolute path.
813
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814.. option:: unique_filename=bool
815
816 To avoid collisions between networked clients, fio defaults to prefixing any
817 generated filenames (with a directory specified) with the source of the
818 client connecting. To disable this behavior, set this option to 0.
819
820.. option:: opendir=str
821
822 Recursively open any files below directory `str`.
823
824.. option:: lockfile=str
825
826 Fio defaults to not locking any files before it does I/O to them. If a file
827 or file descriptor is shared, fio can serialize I/O to that file to make the
828 end result consistent. This is usual for emulating real workloads that share
829 files. The lock modes are:
830
831 **none**
832 No locking. The default.
833 **exclusive**
834 Only one thread or process may do I/O at a time, excluding all
835 others.
836 **readwrite**
837 Read-write locking on the file. Many readers may
838 access the file at the same time, but writes get exclusive access.
839
840.. option:: nrfiles=int
841
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842 Number of files to use for this job. Defaults to 1. The size of files
843 will be :option:`size` divided by this unless explicit size is specified by
844 :option:`filesize`. Files are created for each thread separately, and each
845 file will have a file number within its name by default, as explained in
846 :option:`filename` section.
847
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848
849.. option:: openfiles=int
850
851 Number of files to keep open at the same time. Defaults to the same as
852 :option:`nrfiles`, can be set smaller to limit the number simultaneous
853 opens.
854
855.. option:: file_service_type=str
856
857 Defines how fio decides which file from a job to service next. The following
858 types are defined:
859
860 **random**
861 Choose a file at random.
862
863 **roundrobin**
864 Round robin over opened files. This is the default.
865
866 **sequential**
867 Finish one file before moving on to the next. Multiple files can
f50fbdda 868 still be open depending on :option:`openfiles`.
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869
870 **zipf**
c60ebc45 871 Use a *Zipf* distribution to decide what file to access.
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872
873 **pareto**
c60ebc45 874 Use a *Pareto* distribution to decide what file to access.
f80dba8d 875
dd3503d3 876 **normal**
c60ebc45 877 Use a *Gaussian* (normal) distribution to decide what file to
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878 access.
879
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880 **gauss**
881 Alias for normal.
882
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883 For *random*, *roundrobin*, and *sequential*, a postfix can be appended to
884 tell fio how many I/Os to issue before switching to a new file. For example,
885 specifying ``file_service_type=random:8`` would cause fio to issue
886 8 I/Os before selecting a new file at random. For the non-uniform
887 distributions, a floating point postfix can be given to influence how the
888 distribution is skewed. See :option:`random_distribution` for a description
889 of how that would work.
890
891.. option:: ioscheduler=str
892
893 Attempt to switch the device hosting the file to the specified I/O scheduler
894 before running.
895
896.. option:: create_serialize=bool
897
898 If true, serialize the file creation for the jobs. This may be handy to
899 avoid interleaving of data files, which may greatly depend on the filesystem
a47b697c 900 used and even the number of processors in the system. Default: true.
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901
902.. option:: create_fsync=bool
903
22413915 904 :manpage:`fsync(2)` the data file after creation. This is the default.
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905
906.. option:: create_on_open=bool
907
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908 If true, don't pre-create files but allow the job's open() to create a file
909 when it's time to do I/O. Default: false -- pre-create all necessary files
910 when the job starts.
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911
912.. option:: create_only=bool
913
914 If true, fio will only run the setup phase of the job. If files need to be
4502cb42 915 laid out or updated on disk, only that will be done -- the actual job contents
a47b697c 916 are not executed. Default: false.
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917
918.. option:: allow_file_create=bool
919
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920 If true, fio is permitted to create files as part of its workload. If this
921 option is false, then fio will error out if
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922 the files it needs to use don't already exist. Default: true.
923
924.. option:: allow_mounted_write=bool
925
c60ebc45 926 If this isn't set, fio will abort jobs that are destructive (e.g. that write)
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927 to what appears to be a mounted device or partition. This should help catch
928 creating inadvertently destructive tests, not realizing that the test will
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929 destroy data on the mounted file system. Note that some platforms don't allow
930 writing against a mounted device regardless of this option. Default: false.
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931
932.. option:: pre_read=bool
933
934 If this is given, files will be pre-read into memory before starting the
935 given I/O operation. This will also clear the :option:`invalidate` flag,
936 since it is pointless to pre-read and then drop the cache. This will only
937 work for I/O engines that are seek-able, since they allow you to read the
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938 same data multiple times. Thus it will not work on non-seekable I/O engines
939 (e.g. network, splice). Default: false.
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940
941.. option:: unlink=bool
942
943 Unlink the job files when done. Not the default, as repeated runs of that
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944 job would then waste time recreating the file set again and again. Default:
945 false.
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946
947.. option:: unlink_each_loop=bool
948
a47b697c 949 Unlink job files after each iteration or loop. Default: false.
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950
951.. option:: zonesize=int
952
953 Divide a file into zones of the specified size. See :option:`zoneskip`.
954
955.. option:: zonerange=int
956
957 Give size of an I/O zone. See :option:`zoneskip`.
958
959.. option:: zoneskip=int
960
961 Skip the specified number of bytes when :option:`zonesize` data has been
962 read. The two zone options can be used to only do I/O on zones of a file.
963
964
965I/O type
966~~~~~~~~
967
968.. option:: direct=bool
969
970 If value is true, use non-buffered I/O. This is usually O_DIRECT. Note that
8e889110 971 OpenBSD and ZFS on Solaris don't support direct I/O. On Windows the synchronous
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972 ioengines don't support direct I/O. Default: false.
973
974.. option:: atomic=bool
975
976 If value is true, attempt to use atomic direct I/O. Atomic writes are
977 guaranteed to be stable once acknowledged by the operating system. Only
978 Linux supports O_ATOMIC right now.
979
980.. option:: buffered=bool
981
982 If value is true, use buffered I/O. This is the opposite of the
983 :option:`direct` option. Defaults to true.
984
985.. option:: readwrite=str, rw=str
986
987 Type of I/O pattern. Accepted values are:
988
989 **read**
990 Sequential reads.
991 **write**
992 Sequential writes.
993 **trim**
994 Sequential trims (Linux block devices only).
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995 **randread**
996 Random reads.
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997 **randwrite**
998 Random writes.
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999 **randtrim**
1000 Random trims (Linux block devices only).
1001 **rw,readwrite**
1002 Sequential mixed reads and writes.
1003 **randrw**
1004 Random mixed reads and writes.
1005 **trimwrite**
1006 Sequential trim+write sequences. Blocks will be trimmed first,
1007 then the same blocks will be written to.
1008
1009 Fio defaults to read if the option is not specified. For the mixed I/O
1010 types, the default is to split them 50/50. For certain types of I/O the
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1011 result may still be skewed a bit, since the speed may be different.
1012
1013 It is possible to specify the number of I/Os to do before getting a new
1014 offset by appending ``:<nr>`` to the end of the string given. For a
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1015 random read, it would look like ``rw=randread:8`` for passing in an offset
1016 modifier with a value of 8. If the suffix is used with a sequential I/O
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1017 pattern, then the *<nr>* value specified will be **added** to the generated
1018 offset for each I/O turning sequential I/O into sequential I/O with holes.
1019 For instance, using ``rw=write:4k`` will skip 4k for every write. Also see
1020 the :option:`rw_sequencer` option.
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1021
1022.. option:: rw_sequencer=str
1023
1024 If an offset modifier is given by appending a number to the ``rw=<str>``
1025 line, then this option controls how that number modifies the I/O offset
1026 being generated. Accepted values are:
1027
1028 **sequential**
1029 Generate sequential offset.
1030 **identical**
1031 Generate the same offset.
1032
1033 ``sequential`` is only useful for random I/O, where fio would normally
c60ebc45 1034 generate a new random offset for every I/O. If you append e.g. 8 to randread,
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1035 you would get a new random offset for every 8 I/Os. The result would be a
1036 seek for only every 8 I/Os, instead of for every I/O. Use ``rw=randread:8``
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1037 to specify that. As sequential I/O is already sequential, setting
1038 ``sequential`` for that would not result in any differences. ``identical``
1039 behaves in a similar fashion, except it sends the same offset 8 number of
1040 times before generating a new offset.
1041
1042.. option:: unified_rw_reporting=bool
1043
1044 Fio normally reports statistics on a per data direction basis, meaning that
1045 reads, writes, and trims are accounted and reported separately. If this
1046 option is set fio sums the results and report them as "mixed" instead.
1047
1048.. option:: randrepeat=bool
1049
1050 Seed the random number generator used for random I/O patterns in a
1051 predictable way so the pattern is repeatable across runs. Default: true.
1052
1053.. option:: allrandrepeat=bool
1054
1055 Seed all random number generators in a predictable way so results are
1056 repeatable across runs. Default: false.
1057
1058.. option:: randseed=int
1059
1060 Seed the random number generators based on this seed value, to be able to
1061 control what sequence of output is being generated. If not set, the random
1062 sequence depends on the :option:`randrepeat` setting.
1063
1064.. option:: fallocate=str
1065
1066 Whether pre-allocation is performed when laying down files.
1067 Accepted values are:
1068
1069 **none**
1070 Do not pre-allocate space.
1071
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1072 **native**
1073 Use a platform's native pre-allocation call but fall back to
1074 **none** behavior if it fails/is not implemented.
1075
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1076 **posix**
1077 Pre-allocate via :manpage:`posix_fallocate(3)`.
1078
1079 **keep**
1080 Pre-allocate via :manpage:`fallocate(2)` with
1081 FALLOC_FL_KEEP_SIZE set.
1082
1083 **0**
1084 Backward-compatible alias for **none**.
1085
1086 **1**
1087 Backward-compatible alias for **posix**.
1088
1089 May not be available on all supported platforms. **keep** is only available
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1090 on Linux. If using ZFS on Solaris this cannot be set to **posix**
1091 because ZFS doesn't support pre-allocation. Default: **native** if any
1092 pre-allocation methods are available, **none** if not.
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1093
1094.. option:: fadvise_hint=str
1095
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1096 Use :manpage:`posix_fadvise(2)` or :manpage:`posix_fadvise(2)` to
1097 advise the kernel on what I/O patterns are likely to be issued.
1098 Accepted values are:
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1099
1100 **0**
1101 Backwards-compatible hint for "no hint".
1102
1103 **1**
1104 Backwards compatible hint for "advise with fio workload type". This
1105 uses **FADV_RANDOM** for a random workload, and **FADV_SEQUENTIAL**
1106 for a sequential workload.
1107
1108 **sequential**
1109 Advise using **FADV_SEQUENTIAL**.
1110
1111 **random**
1112 Advise using **FADV_RANDOM**.
1113
8f4b9f24 1114.. option:: write_hint=str
f80dba8d 1115
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1116 Use :manpage:`fcntl(2)` to advise the kernel what life time to expect
1117 from a write. Only supported on Linux, as of version 4.13. Accepted
1118 values are:
1119
1120 **none**
1121 No particular life time associated with this file.
1122
1123 **short**
1124 Data written to this file has a short life time.
1125
1126 **medium**
1127 Data written to this file has a medium life time.
1128
1129 **long**
1130 Data written to this file has a long life time.
1131
1132 **extreme**
1133 Data written to this file has a very long life time.
1134
1135 The values are all relative to each other, and no absolute meaning
1136 should be associated with them.
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1137
1138.. option:: offset=int
1139
82dbb8cb 1140 Start I/O at the provided offset in the file, given as either a fixed size in
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1141 bytes or a percentage. If a percentage is given, the generated offset will be
1142 aligned to the minimum ``blocksize`` or to the value of ``offset_align`` if
1143 provided. Data before the given offset will not be touched. This
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1144 effectively caps the file size at `real_size - offset`. Can be combined with
1145 :option:`size` to constrain the start and end range of the I/O workload.
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1146 A percentage can be specified by a number between 1 and 100 followed by '%',
1147 for example, ``offset=20%`` to specify 20%.
f80dba8d 1148
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1149.. option:: offset_align=int
1150
1151 If set to non-zero value, the byte offset generated by a percentage ``offset``
1152 is aligned upwards to this value. Defaults to 0 meaning that a percentage
1153 offset is aligned to the minimum block size.
1154
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1155.. option:: offset_increment=int
1156
1157 If this is provided, then the real offset becomes `offset + offset_increment
1158 * thread_number`, where the thread number is a counter that starts at 0 and
1159 is incremented for each sub-job (i.e. when :option:`numjobs` option is
1160 specified). This option is useful if there are several jobs which are
1161 intended to operate on a file in parallel disjoint segments, with even
1162 spacing between the starting points.
1163
1164.. option:: number_ios=int
1165
c60ebc45 1166 Fio will normally perform I/Os until it has exhausted the size of the region
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1167 set by :option:`size`, or if it exhaust the allocated time (or hits an error
1168 condition). With this setting, the range/size can be set independently of
c60ebc45 1169 the number of I/Os to perform. When fio reaches this number, it will exit
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1170 normally and report status. Note that this does not extend the amount of I/O
1171 that will be done, it will only stop fio if this condition is met before
1172 other end-of-job criteria.
1173
1174.. option:: fsync=int
1175
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1176 If writing to a file, issue an :manpage:`fsync(2)` (or its equivalent) of
1177 the dirty data for every number of blocks given. For example, if you give 32
1178 as a parameter, fio will sync the file after every 32 writes issued. If fio is
1179 using non-buffered I/O, we may not sync the file. The exception is the sg
1180 I/O engine, which synchronizes the disk cache anyway. Defaults to 0, which
1181 means fio does not periodically issue and wait for a sync to complete. Also
1182 see :option:`end_fsync` and :option:`fsync_on_close`.
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1183
1184.. option:: fdatasync=int
1185
1186 Like :option:`fsync` but uses :manpage:`fdatasync(2)` to only sync data and
000a5f1c 1187 not metadata blocks. In Windows, FreeBSD, and DragonFlyBSD there is no
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1188 :manpage:`fdatasync(2)` so this falls back to using :manpage:`fsync(2)`.
1189 Defaults to 0, which means fio does not periodically issue and wait for a
1190 data-only sync to complete.
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1191
1192.. option:: write_barrier=int
1193
2831be97 1194 Make every `N-th` write a barrier write.
f80dba8d 1195
f50fbdda 1196.. option:: sync_file_range=str:int
f80dba8d 1197
f50fbdda 1198 Use :manpage:`sync_file_range(2)` for every `int` number of write
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1199 operations. Fio will track range of writes that have happened since the last
1200 :manpage:`sync_file_range(2)` call. `str` can currently be one or more of:
1201
1202 **wait_before**
1203 SYNC_FILE_RANGE_WAIT_BEFORE
1204 **write**
1205 SYNC_FILE_RANGE_WRITE
1206 **wait_after**
1207 SYNC_FILE_RANGE_WAIT_AFTER
1208
1209 So if you do ``sync_file_range=wait_before,write:8``, fio would use
1210 ``SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE`` for every 8
1211 writes. Also see the :manpage:`sync_file_range(2)` man page. This option is
1212 Linux specific.
1213
1214.. option:: overwrite=bool
1215
1216 If true, writes to a file will always overwrite existing data. If the file
1217 doesn't already exist, it will be created before the write phase begins. If
1218 the file exists and is large enough for the specified write phase, nothing
a47b697c 1219 will be done. Default: false.
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1220
1221.. option:: end_fsync=bool
1222
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1223 If true, :manpage:`fsync(2)` file contents when a write stage has completed.
1224 Default: false.
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1225
1226.. option:: fsync_on_close=bool
1227
1228 If true, fio will :manpage:`fsync(2)` a dirty file on close. This differs
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1229 from :option:`end_fsync` in that it will happen on every file close, not
1230 just at the end of the job. Default: false.
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1231
1232.. option:: rwmixread=int
1233
1234 Percentage of a mixed workload that should be reads. Default: 50.
1235
1236.. option:: rwmixwrite=int
1237
1238 Percentage of a mixed workload that should be writes. If both
1239 :option:`rwmixread` and :option:`rwmixwrite` is given and the values do not
1240 add up to 100%, the latter of the two will be used to override the
1241 first. This may interfere with a given rate setting, if fio is asked to
1242 limit reads or writes to a certain rate. If that is the case, then the
1243 distribution may be skewed. Default: 50.
1244
1245.. option:: random_distribution=str:float[,str:float][,str:float]
1246
1247 By default, fio will use a completely uniform random distribution when asked
1248 to perform random I/O. Sometimes it is useful to skew the distribution in
1249 specific ways, ensuring that some parts of the data is more hot than others.
1250 fio includes the following distribution models:
1251
1252 **random**
1253 Uniform random distribution
1254
1255 **zipf**
1256 Zipf distribution
1257
1258 **pareto**
1259 Pareto distribution
1260
b2f4b559 1261 **normal**
c60ebc45 1262 Normal (Gaussian) distribution
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1263
1264 **zoned**
1265 Zoned random distribution
1266
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1267 **zoned_abs**
1268 Zone absolute random distribution
1269
f80dba8d 1270 When using a **zipf** or **pareto** distribution, an input value is also
f50fbdda 1271 needed to define the access pattern. For **zipf**, this is the `Zipf
c60ebc45 1272 theta`. For **pareto**, it's the `Pareto power`. Fio includes a test
f50fbdda 1273 program, :command:`fio-genzipf`, that can be used visualize what the given input
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1274 values will yield in terms of hit rates. If you wanted to use **zipf** with
1275 a `theta` of 1.2, you would use ``random_distribution=zipf:1.2`` as the
1276 option. If a non-uniform model is used, fio will disable use of the random
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1277 map. For the **normal** distribution, a normal (Gaussian) deviation is
1278 supplied as a value between 0 and 100.
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1279
1280 For a **zoned** distribution, fio supports specifying percentages of I/O
1281 access that should fall within what range of the file or device. For
1282 example, given a criteria of:
1283
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1284 * 60% of accesses should be to the first 10%
1285 * 30% of accesses should be to the next 20%
1286 * 8% of accesses should be to the next 30%
1287 * 2% of accesses should be to the next 40%
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1288
1289 we can define that through zoning of the random accesses. For the above
1290 example, the user would do::
1291
1292 random_distribution=zoned:60/10:30/20:8/30:2/40
1293
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1294 A **zoned_abs** distribution works exactly like the **zoned**, except
1295 that it takes absolute sizes. For example, let's say you wanted to
1296 define access according to the following criteria:
1297
1298 * 60% of accesses should be to the first 20G
1299 * 30% of accesses should be to the next 100G
1300 * 10% of accesses should be to the next 500G
1301
1302 we can define an absolute zoning distribution with:
1303
1304 random_distribution=zoned_abs=60/20G:30/100G:10/500g
1305
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1306 For both **zoned** and **zoned_abs**, fio supports defining up to
1307 256 separate zones.
1308
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1309 Similarly to how :option:`bssplit` works for setting ranges and
1310 percentages of block sizes. Like :option:`bssplit`, it's possible to
1311 specify separate zones for reads, writes, and trims. If just one set
1312 is given, it'll apply to all of them. This goes for both **zoned**
1313 **zoned_abs** distributions.
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1314
1315.. option:: percentage_random=int[,int][,int]
1316
1317 For a random workload, set how big a percentage should be random. This
1318 defaults to 100%, in which case the workload is fully random. It can be set
1319 from anywhere from 0 to 100. Setting it to 0 would make the workload fully
1320 sequential. Any setting in between will result in a random mix of sequential
1321 and random I/O, at the given percentages. Comma-separated values may be
1322 specified for reads, writes, and trims as described in :option:`blocksize`.
1323
1324.. option:: norandommap
1325
1326 Normally fio will cover every block of the file when doing random I/O. If
1327 this option is given, fio will just get a new random offset without looking
1328 at past I/O history. This means that some blocks may not be read or written,
1329 and that some blocks may be read/written more than once. If this option is
1330 used with :option:`verify` and multiple blocksizes (via :option:`bsrange`),
1331 only intact blocks are verified, i.e., partially-overwritten blocks are
1332 ignored.
1333
1334.. option:: softrandommap=bool
1335
1336 See :option:`norandommap`. If fio runs with the random block map enabled and
1337 it fails to allocate the map, if this option is set it will continue without
1338 a random block map. As coverage will not be as complete as with random maps,
1339 this option is disabled by default.
1340
1341.. option:: random_generator=str
1342
f50fbdda 1343 Fio supports the following engines for generating I/O offsets for random I/O:
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1344
1345 **tausworthe**
f50fbdda 1346 Strong 2^88 cycle random number generator.
f80dba8d 1347 **lfsr**
f50fbdda 1348 Linear feedback shift register generator.
f80dba8d 1349 **tausworthe64**
f50fbdda 1350 Strong 64-bit 2^258 cycle random number generator.
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1351
1352 **tausworthe** is a strong random number generator, but it requires tracking
1353 on the side if we want to ensure that blocks are only read or written
f50fbdda 1354 once. **lfsr** guarantees that we never generate the same offset twice, and
f80dba8d 1355 it's also less computationally expensive. It's not a true random generator,
f50fbdda 1356 however, though for I/O purposes it's typically good enough. **lfsr** only
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1357 works with single block sizes, not with workloads that use multiple block
1358 sizes. If used with such a workload, fio may read or write some blocks
1359 multiple times. The default value is **tausworthe**, unless the required
1360 space exceeds 2^32 blocks. If it does, then **tausworthe64** is
1361 selected automatically.
1362
1363
1364Block size
1365~~~~~~~~~~
1366
1367.. option:: blocksize=int[,int][,int], bs=int[,int][,int]
1368
1369 The block size in bytes used for I/O units. Default: 4096. A single value
1370 applies to reads, writes, and trims. Comma-separated values may be
1371 specified for reads, writes, and trims. A value not terminated in a comma
1372 applies to subsequent types.
1373
1374 Examples:
1375
1376 **bs=256k**
1377 means 256k for reads, writes and trims.
1378
1379 **bs=8k,32k**
1380 means 8k for reads, 32k for writes and trims.
1381
1382 **bs=8k,32k,**
1383 means 8k for reads, 32k for writes, and default for trims.
1384
1385 **bs=,8k**
1386 means default for reads, 8k for writes and trims.
1387
1388 **bs=,8k,**
b443ae44 1389 means default for reads, 8k for writes, and default for trims.
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1390
1391.. option:: blocksize_range=irange[,irange][,irange], bsrange=irange[,irange][,irange]
1392
1393 A range of block sizes in bytes for I/O units. The issued I/O unit will
1394 always be a multiple of the minimum size, unless
1395 :option:`blocksize_unaligned` is set.
1396
1397 Comma-separated ranges may be specified for reads, writes, and trims as
1398 described in :option:`blocksize`.
1399
1400 Example: ``bsrange=1k-4k,2k-8k``.
1401
1402.. option:: bssplit=str[,str][,str]
1403
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1404 Sometimes you want even finer grained control of the block sizes
1405 issued, not just an even split between them. This option allows you to
1406 weight various block sizes, so that you are able to define a specific
1407 amount of block sizes issued. The format for this option is::
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1408
1409 bssplit=blocksize/percentage:blocksize/percentage
1410
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1411 for as many block sizes as needed. So if you want to define a workload
1412 that has 50% 64k blocks, 10% 4k blocks, and 40% 32k blocks, you would
1413 write::
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1414
1415 bssplit=4k/10:64k/50:32k/40
1416
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1417 Ordering does not matter. If the percentage is left blank, fio will
1418 fill in the remaining values evenly. So a bssplit option like this one::
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1419
1420 bssplit=4k/50:1k/:32k/
1421
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1422 would have 50% 4k ios, and 25% 1k and 32k ios. The percentages always
1423 add up to 100, if bssplit is given a range that adds up to more, it
1424 will error out.
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1425
1426 Comma-separated values may be specified for reads, writes, and trims as
1427 described in :option:`blocksize`.
1428
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1429 If you want a workload that has 50% 2k reads and 50% 4k reads, while
1430 having 90% 4k writes and 10% 8k writes, you would specify::
f80dba8d 1431
cf04b906 1432 bssplit=2k/50:4k/50,4k/90:8k/10
f80dba8d 1433
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1434 Fio supports defining up to 64 different weights for each data
1435 direction.
1436
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1437.. option:: blocksize_unaligned, bs_unaligned
1438
1439 If set, fio will issue I/O units with any size within
1440 :option:`blocksize_range`, not just multiples of the minimum size. This
1441 typically won't work with direct I/O, as that normally requires sector
1442 alignment.
1443
589e88b7 1444.. option:: bs_is_seq_rand=bool
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1445
1446 If this option is set, fio will use the normal read,write blocksize settings
1447 as sequential,random blocksize settings instead. Any random read or write
1448 will use the WRITE blocksize settings, and any sequential read or write will
1449 use the READ blocksize settings.
1450
1451.. option:: blockalign=int[,int][,int], ba=int[,int][,int]
1452
1453 Boundary to which fio will align random I/O units. Default:
1454 :option:`blocksize`. Minimum alignment is typically 512b for using direct
1455 I/O, though it usually depends on the hardware block size. This option is
1456 mutually exclusive with using a random map for files, so it will turn off
1457 that option. Comma-separated values may be specified for reads, writes, and
1458 trims as described in :option:`blocksize`.
1459
1460
1461Buffers and memory
1462~~~~~~~~~~~~~~~~~~
1463
1464.. option:: zero_buffers
1465
1466 Initialize buffers with all zeros. Default: fill buffers with random data.
1467
1468.. option:: refill_buffers
1469
1470 If this option is given, fio will refill the I/O buffers on every
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1471 submit. Only makes sense if :option:`zero_buffers` isn't specified,
1472 naturally. Defaults to being unset i.e., the buffer is only filled at
1473 init time and the data in it is reused when possible but if any of
1474 :option:`verify`, :option:`buffer_compress_percentage` or
1475 :option:`dedupe_percentage` are enabled then `refill_buffers` is also
1476 automatically enabled.
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1477
1478.. option:: scramble_buffers=bool
1479
1480 If :option:`refill_buffers` is too costly and the target is using data
1481 deduplication, then setting this option will slightly modify the I/O buffer
1482 contents to defeat normal de-dupe attempts. This is not enough to defeat
1483 more clever block compression attempts, but it will stop naive dedupe of
1484 blocks. Default: true.
1485
1486.. option:: buffer_compress_percentage=int
1487
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1488 If this is set, then fio will attempt to provide I/O buffer content
1489 (on WRITEs) that compresses to the specified level. Fio does this by
1490 providing a mix of random data followed by fixed pattern data. The
1491 fixed pattern is either zeros, or the pattern specified by
1492 :option:`buffer_pattern`. If the `buffer_pattern` option is used, it
1493 might skew the compression ratio slightly. Setting
1494 `buffer_compress_percentage` to a value other than 100 will also
1495 enable :option:`refill_buffers` in order to reduce the likelihood that
1496 adjacent blocks are so similar that they over compress when seen
1497 together. See :option:`buffer_compress_chunk` for how to set a finer or
1498 coarser granularity for the random/fixed data region. Defaults to unset
1499 i.e., buffer data will not adhere to any compression level.
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1500
1501.. option:: buffer_compress_chunk=int
1502
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1503 This setting allows fio to manage how big the random/fixed data region
1504 is when using :option:`buffer_compress_percentage`. When
1505 `buffer_compress_chunk` is set to some non-zero value smaller than the
1506 block size, fio can repeat the random/fixed region throughout the I/O
1507 buffer at the specified interval (which particularly useful when
1508 bigger block sizes are used for a job). When set to 0, fio will use a
1509 chunk size that matches the block size resulting in a single
1510 random/fixed region within the I/O buffer. Defaults to 512. When the
1511 unit is omitted, the value is interpreted in bytes.
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1512
1513.. option:: buffer_pattern=str
1514
a1554f65
SB
1515 If set, fio will fill the I/O buffers with this pattern or with the contents
1516 of a file. If not set, the contents of I/O buffers are defined by the other
1517 options related to buffer contents. The setting can be any pattern of bytes,
1518 and can be prefixed with 0x for hex values. It may also be a string, where
1519 the string must then be wrapped with ``""``. Or it may also be a filename,
1520 where the filename must be wrapped with ``''`` in which case the file is
1521 opened and read. Note that not all the file contents will be read if that
1522 would cause the buffers to overflow. So, for example::
1523
1524 buffer_pattern='filename'
1525
1526 or::
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1527
1528 buffer_pattern="abcd"
1529
1530 or::
1531
1532 buffer_pattern=-12
1533
1534 or::
1535
1536 buffer_pattern=0xdeadface
1537
1538 Also you can combine everything together in any order::
1539
a1554f65 1540 buffer_pattern=0xdeadface"abcd"-12'filename'
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1541
1542.. option:: dedupe_percentage=int
1543
1544 If set, fio will generate this percentage of identical buffers when
1545 writing. These buffers will be naturally dedupable. The contents of the
1546 buffers depend on what other buffer compression settings have been set. It's
1547 possible to have the individual buffers either fully compressible, or not at
72592780
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1548 all -- this option only controls the distribution of unique buffers. Setting
1549 this option will also enable :option:`refill_buffers` to prevent every buffer
1550 being identical.
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1551
1552.. option:: invalidate=bool
1553
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1554 Invalidate the buffer/page cache parts of the files to be used prior to
1555 starting I/O if the platform and file type support it. Defaults to true.
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1556 This will be ignored if :option:`pre_read` is also specified for the
1557 same job.
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1558
1559.. option:: sync=bool
1560
1561 Use synchronous I/O for buffered writes. For the majority of I/O engines,
1562 this means using O_SYNC. Default: false.
1563
1564.. option:: iomem=str, mem=str
1565
1566 Fio can use various types of memory as the I/O unit buffer. The allowed
1567 values are:
1568
1569 **malloc**
1570 Use memory from :manpage:`malloc(3)` as the buffers. Default memory
1571 type.
1572
1573 **shm**
1574 Use shared memory as the buffers. Allocated through
1575 :manpage:`shmget(2)`.
1576
1577 **shmhuge**
1578 Same as shm, but use huge pages as backing.
1579
1580 **mmap**
22413915 1581 Use :manpage:`mmap(2)` to allocate buffers. May either be anonymous memory, or can
f80dba8d
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1582 be file backed if a filename is given after the option. The format
1583 is `mem=mmap:/path/to/file`.
1584
1585 **mmaphuge**
1586 Use a memory mapped huge file as the buffer backing. Append filename
1587 after mmaphuge, ala `mem=mmaphuge:/hugetlbfs/file`.
1588
1589 **mmapshared**
1590 Same as mmap, but use a MMAP_SHARED mapping.
1591
03553853
YR
1592 **cudamalloc**
1593 Use GPU memory as the buffers for GPUDirect RDMA benchmark.
f50fbdda 1594 The :option:`ioengine` must be `rdma`.
03553853 1595
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1596 The area allocated is a function of the maximum allowed bs size for the job,
1597 multiplied by the I/O depth given. Note that for **shmhuge** and
1598 **mmaphuge** to work, the system must have free huge pages allocated. This
1599 can normally be checked and set by reading/writing
1600 :file:`/proc/sys/vm/nr_hugepages` on a Linux system. Fio assumes a huge page
1601 is 4MiB in size. So to calculate the number of huge pages you need for a
1602 given job file, add up the I/O depth of all jobs (normally one unless
1603 :option:`iodepth` is used) and multiply by the maximum bs set. Then divide
1604 that number by the huge page size. You can see the size of the huge pages in
1605 :file:`/proc/meminfo`. If no huge pages are allocated by having a non-zero
1606 number in `nr_hugepages`, using **mmaphuge** or **shmhuge** will fail. Also
1607 see :option:`hugepage-size`.
1608
1609 **mmaphuge** also needs to have hugetlbfs mounted and the file location
1610 should point there. So if it's mounted in :file:`/huge`, you would use
1611 `mem=mmaphuge:/huge/somefile`.
1612
f50fbdda 1613.. option:: iomem_align=int, mem_align=int
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1614
1615 This indicates the memory alignment of the I/O memory buffers. Note that
1616 the given alignment is applied to the first I/O unit buffer, if using
1617 :option:`iodepth` the alignment of the following buffers are given by the
1618 :option:`bs` used. In other words, if using a :option:`bs` that is a
1619 multiple of the page sized in the system, all buffers will be aligned to
1620 this value. If using a :option:`bs` that is not page aligned, the alignment
1621 of subsequent I/O memory buffers is the sum of the :option:`iomem_align` and
1622 :option:`bs` used.
1623
1624.. option:: hugepage-size=int
1625
1626 Defines the size of a huge page. Must at least be equal to the system
1627 setting, see :file:`/proc/meminfo`. Defaults to 4MiB. Should probably
1628 always be a multiple of megabytes, so using ``hugepage-size=Xm`` is the
1629 preferred way to set this to avoid setting a non-pow-2 bad value.
1630
1631.. option:: lockmem=int
1632
1633 Pin the specified amount of memory with :manpage:`mlock(2)`. Can be used to
1634 simulate a smaller amount of memory. The amount specified is per worker.
1635
1636
1637I/O size
1638~~~~~~~~
1639
1640.. option:: size=int
1641
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1642 The total size of file I/O for each thread of this job. Fio will run until
1643 this many bytes has been transferred, unless runtime is limited by other options
1644 (such as :option:`runtime`, for instance, or increased/decreased by :option:`io_size`).
1645 Fio will divide this size between the available files determined by options
1646 such as :option:`nrfiles`, :option:`filename`, unless :option:`filesize` is
1647 specified by the job. If the result of division happens to be 0, the size is
c4aa2d08 1648 set to the physical size of the given files or devices if they exist.
79591fa9 1649 If this option is not specified, fio will use the full size of the given
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1650 files or devices. If the files do not exist, size must be given. It is also
1651 possible to give size as a percentage between 1 and 100. If ``size=20%`` is
1652 given, fio will use 20% of the full size of the given files or devices.
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1653 Can be combined with :option:`offset` to constrain the start and end range
1654 that I/O will be done within.
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1655
1656.. option:: io_size=int, io_limit=int
1657
1658 Normally fio operates within the region set by :option:`size`, which means
1659 that the :option:`size` option sets both the region and size of I/O to be
1660 performed. Sometimes that is not what you want. With this option, it is
1661 possible to define just the amount of I/O that fio should do. For instance,
1662 if :option:`size` is set to 20GiB and :option:`io_size` is set to 5GiB, fio
1663 will perform I/O within the first 20GiB but exit when 5GiB have been
1664 done. The opposite is also possible -- if :option:`size` is set to 20GiB,
1665 and :option:`io_size` is set to 40GiB, then fio will do 40GiB of I/O within
1666 the 0..20GiB region.
1667
7fdd97ca 1668.. option:: filesize=irange(int)
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1669
1670 Individual file sizes. May be a range, in which case fio will select sizes
1671 for files at random within the given range and limited to :option:`size` in
1672 total (if that is given). If not given, each created file is the same size.
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1673 This option overrides :option:`size` in terms of file size, which means
1674 this value is used as a fixed size or possible range of each file.
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1675
1676.. option:: file_append=bool
1677
1678 Perform I/O after the end of the file. Normally fio will operate within the
1679 size of a file. If this option is set, then fio will append to the file
1680 instead. This has identical behavior to setting :option:`offset` to the size
1681 of a file. This option is ignored on non-regular files.
1682
1683.. option:: fill_device=bool, fill_fs=bool
1684
1685 Sets size to something really large and waits for ENOSPC (no space left on
1686 device) as the terminating condition. Only makes sense with sequential
1687 write. For a read workload, the mount point will be filled first then I/O
1688 started on the result. This option doesn't make sense if operating on a raw
1689 device node, since the size of that is already known by the file system.
1690 Additionally, writing beyond end-of-device will not return ENOSPC there.
1691
1692
1693I/O engine
1694~~~~~~~~~~
1695
1696.. option:: ioengine=str
1697
1698 Defines how the job issues I/O to the file. The following types are defined:
1699
1700 **sync**
1701 Basic :manpage:`read(2)` or :manpage:`write(2)`
1702 I/O. :manpage:`lseek(2)` is used to position the I/O location.
54227e6b 1703 See :option:`fsync` and :option:`fdatasync` for syncing write I/Os.
f80dba8d
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1704
1705 **psync**
1706 Basic :manpage:`pread(2)` or :manpage:`pwrite(2)` I/O. Default on
1707 all supported operating systems except for Windows.
1708
1709 **vsync**
1710 Basic :manpage:`readv(2)` or :manpage:`writev(2)` I/O. Will emulate
c60ebc45 1711 queuing by coalescing adjacent I/Os into a single submission.
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1712
1713 **pvsync**
1714 Basic :manpage:`preadv(2)` or :manpage:`pwritev(2)` I/O.
1715
1716 **pvsync2**
1717 Basic :manpage:`preadv2(2)` or :manpage:`pwritev2(2)` I/O.
1718
1719 **libaio**
1720 Linux native asynchronous I/O. Note that Linux may only support
22413915 1721 queued behavior with non-buffered I/O (set ``direct=1`` or
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1722 ``buffered=0``).
1723 This engine defines engine specific options.
1724
1725 **posixaio**
1726 POSIX asynchronous I/O using :manpage:`aio_read(3)` and
1727 :manpage:`aio_write(3)`.
1728
1729 **solarisaio**
1730 Solaris native asynchronous I/O.
1731
1732 **windowsaio**
1733 Windows native asynchronous I/O. Default on Windows.
1734
1735 **mmap**
1736 File is memory mapped with :manpage:`mmap(2)` and data copied
1737 to/from using :manpage:`memcpy(3)`.
1738
1739 **splice**
1740 :manpage:`splice(2)` is used to transfer the data and
1741 :manpage:`vmsplice(2)` to transfer data from user space to the
1742 kernel.
1743
1744 **sg**
1745 SCSI generic sg v3 I/O. May either be synchronous using the SG_IO
1746 ioctl, or if the target is an sg character device we use
1747 :manpage:`read(2)` and :manpage:`write(2)` for asynchronous
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1748 I/O. Requires :option:`filename` option to specify either block or
1749 character devices.
52b81b7c 1750 The sg engine includes engine specific options.
f80dba8d
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1751
1752 **null**
1753 Doesn't transfer any data, just pretends to. This is mainly used to
1754 exercise fio itself and for debugging/testing purposes.
1755
1756 **net**
1757 Transfer over the network to given ``host:port``. Depending on the
1758 :option:`protocol` used, the :option:`hostname`, :option:`port`,
1759 :option:`listen` and :option:`filename` options are used to specify
1760 what sort of connection to make, while the :option:`protocol` option
1761 determines which protocol will be used. This engine defines engine
1762 specific options.
1763
1764 **netsplice**
1765 Like **net**, but uses :manpage:`splice(2)` and
1766 :manpage:`vmsplice(2)` to map data and send/receive.
1767 This engine defines engine specific options.
1768
1769 **cpuio**
1770 Doesn't transfer any data, but burns CPU cycles according to the
1771 :option:`cpuload` and :option:`cpuchunks` options. Setting
9207a0cb 1772 :option:`cpuload`\=85 will cause that job to do nothing but burn 85%
71aa48eb 1773 of the CPU. In case of SMP machines, use :option:`numjobs`\=<nr_of_cpu>
f50fbdda 1774 to get desired CPU usage, as the cpuload only loads a
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1775 single CPU at the desired rate. A job never finishes unless there is
1776 at least one non-cpuio job.
1777
1778 **guasi**
804c0839 1779 The GUASI I/O engine is the Generic Userspace Asynchronous Syscall
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1780 Interface approach to async I/O. See
1781
1782 http://www.xmailserver.org/guasi-lib.html
1783
1784 for more info on GUASI.
1785
1786 **rdma**
1787 The RDMA I/O engine supports both RDMA memory semantics
1788 (RDMA_WRITE/RDMA_READ) and channel semantics (Send/Recv) for the
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1789 InfiniBand, RoCE and iWARP protocols. This engine defines engine
1790 specific options.
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1791
1792 **falloc**
1793 I/O engine that does regular fallocate to simulate data transfer as
1794 fio ioengine.
1795
1796 DDIR_READ
1797 does fallocate(,mode = FALLOC_FL_KEEP_SIZE,).
1798
1799 DDIR_WRITE
1800 does fallocate(,mode = 0).
1801
1802 DDIR_TRIM
1803 does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE).
1804
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1805 **ftruncate**
1806 I/O engine that sends :manpage:`ftruncate(2)` operations in response
1807 to write (DDIR_WRITE) events. Each ftruncate issued sets the file's
f50fbdda 1808 size to the current block offset. :option:`blocksize` is ignored.
761cd093 1809
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1810 **e4defrag**
1811 I/O engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate
1812 defragment activity in request to DDIR_WRITE event.
1813
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1814 **rados**
1815 I/O engine supporting direct access to Ceph Reliable Autonomic
1816 Distributed Object Store (RADOS) via librados. This ioengine
1817 defines engine specific options.
1818
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1819 **rbd**
1820 I/O engine supporting direct access to Ceph Rados Block Devices
1821 (RBD) via librbd without the need to use the kernel rbd driver. This
1822 ioengine defines engine specific options.
1823
1824 **gfapi**
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1825 Using GlusterFS libgfapi sync interface to direct access to
1826 GlusterFS volumes without having to go through FUSE. This ioengine
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1827 defines engine specific options.
1828
1829 **gfapi_async**
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1830 Using GlusterFS libgfapi async interface to direct access to
1831 GlusterFS volumes without having to go through FUSE. This ioengine
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1832 defines engine specific options.
1833
1834 **libhdfs**
f50fbdda 1835 Read and write through Hadoop (HDFS). The :option:`filename` option
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1836 is used to specify host,port of the hdfs name-node to connect. This
1837 engine interprets offsets a little differently. In HDFS, files once
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1838 created cannot be modified so random writes are not possible. To
1839 imitate this the libhdfs engine expects a bunch of small files to be
1840 created over HDFS and will randomly pick a file from them
1841 based on the offset generated by fio backend (see the example
f80dba8d 1842 job file to create such files, use ``rw=write`` option). Please
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1843 note, it may be necessary to set environment variables to work
1844 with HDFS/libhdfs properly. Each job uses its own connection to
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1845 HDFS.
1846
1847 **mtd**
1848 Read, write and erase an MTD character device (e.g.,
1849 :file:`/dev/mtd0`). Discards are treated as erases. Depending on the
1850 underlying device type, the I/O may have to go in a certain pattern,
1851 e.g., on NAND, writing sequentially to erase blocks and discarding
c298ee71 1852 before overwriting. The `trimwrite` mode works well for this
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1853 constraint.
1854
1855 **pmemblk**
1856 Read and write using filesystem DAX to a file on a filesystem
363a5f65 1857 mounted with DAX on a persistent memory device through the PMDK
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1858 libpmemblk library.
1859
1860 **dev-dax**
1861 Read and write using device DAX to a persistent memory device (e.g.,
363a5f65 1862 /dev/dax0.0) through the PMDK libpmem library.
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1863
1864 **external**
1865 Prefix to specify loading an external I/O engine object file. Append
c60ebc45 1866 the engine filename, e.g. ``ioengine=external:/tmp/foo.o`` to load
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1867 ioengine :file:`foo.o` in :file:`/tmp`. The path can be either
1868 absolute or relative. See :file:`engines/skeleton_external.c` for
1869 details of writing an external I/O engine.
f80dba8d 1870
1216cc5a 1871 **filecreate**
b71968b1 1872 Simply create the files and do no I/O to them. You still need to
1216cc5a 1873 set `filesize` so that all the accounting still occurs, but no
b71968b1 1874 actual I/O will be done other than creating the file.
f80dba8d 1875
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1876 **libpmem**
1877 Read and write using mmap I/O to a file on a filesystem
363a5f65 1878 mounted with DAX on a persistent memory device through the PMDK
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1879 libpmem library.
1880
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1881I/O engine specific parameters
1882~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1883
1884In addition, there are some parameters which are only valid when a specific
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1885:option:`ioengine` is in use. These are used identically to normal parameters,
1886with the caveat that when used on the command line, they must come after the
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1887:option:`ioengine` that defines them is selected.
1888
1889.. option:: userspace_reap : [libaio]
1890
1891 Normally, with the libaio engine in use, fio will use the
1892 :manpage:`io_getevents(2)` system call to reap newly returned events. With
1893 this flag turned on, the AIO ring will be read directly from user-space to
1894 reap events. The reaping mode is only enabled when polling for a minimum of
c60ebc45 1895 0 events (e.g. when :option:`iodepth_batch_complete` `=0`).
f80dba8d 1896
9d25d068 1897.. option:: hipri : [pvsync2]
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1898
1899 Set RWF_HIPRI on I/O, indicating to the kernel that it's of higher priority
1900 than normal.
1901
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1902.. option:: hipri_percentage : [pvsync2]
1903
f50fbdda 1904 When hipri is set this determines the probability of a pvsync2 I/O being high
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1905 priority. The default is 100%.
1906
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1907.. option:: cpuload=int : [cpuio]
1908
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1909 Attempt to use the specified percentage of CPU cycles. This is a mandatory
1910 option when using cpuio I/O engine.
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1911
1912.. option:: cpuchunks=int : [cpuio]
1913
1914 Split the load into cycles of the given time. In microseconds.
1915
1916.. option:: exit_on_io_done=bool : [cpuio]
1917
1918 Detect when I/O threads are done, then exit.
1919
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1920.. option:: namenode=str : [libhdfs]
1921
22413915 1922 The hostname or IP address of a HDFS cluster namenode to contact.
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1923
1924.. option:: port=int
1925
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1926 [libhdfs]
1927
1928 The listening port of the HFDS cluster namenode.
1929
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1930 [netsplice], [net]
1931
1932 The TCP or UDP port to bind to or connect to. If this is used with
1933 :option:`numjobs` to spawn multiple instances of the same job type, then
1934 this will be the starting port number since fio will use a range of
1935 ports.
1936
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1937 [rdma]
1938
1939 The port to use for RDMA-CM communication. This should be the same value
1940 on the client and the server side.
1941
1942.. option:: hostname=str : [netsplice] [net] [rdma]
f80dba8d 1943
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1944 The hostname or IP address to use for TCP, UDP or RDMA-CM based I/O. If the job
1945 is a TCP listener or UDP reader, the hostname is not used and must be omitted
f50fbdda 1946 unless it is a valid UDP multicast address.
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1947
1948.. option:: interface=str : [netsplice] [net]
1949
1950 The IP address of the network interface used to send or receive UDP
1951 multicast.
1952
1953.. option:: ttl=int : [netsplice] [net]
1954
1955 Time-to-live value for outgoing UDP multicast packets. Default: 1.
1956
1957.. option:: nodelay=bool : [netsplice] [net]
1958
1959 Set TCP_NODELAY on TCP connections.
1960
f50fbdda 1961.. option:: protocol=str, proto=str : [netsplice] [net]
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1962
1963 The network protocol to use. Accepted values are:
1964
1965 **tcp**
1966 Transmission control protocol.
1967 **tcpv6**
1968 Transmission control protocol V6.
1969 **udp**
1970 User datagram protocol.
1971 **udpv6**
1972 User datagram protocol V6.
1973 **unix**
1974 UNIX domain socket.
1975
1976 When the protocol is TCP or UDP, the port must also be given, as well as the
1977 hostname if the job is a TCP listener or UDP reader. For unix sockets, the
f50fbdda 1978 normal :option:`filename` option should be used and the port is invalid.
f80dba8d 1979
e9184ec1 1980.. option:: listen : [netsplice] [net]
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1981
1982 For TCP network connections, tell fio to listen for incoming connections
1983 rather than initiating an outgoing connection. The :option:`hostname` must
1984 be omitted if this option is used.
1985
e9184ec1 1986.. option:: pingpong : [netsplice] [net]
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1987
1988 Normally a network writer will just continue writing data, and a network
1989 reader will just consume packages. If ``pingpong=1`` is set, a writer will
1990 send its normal payload to the reader, then wait for the reader to send the
1991 same payload back. This allows fio to measure network latencies. The
1992 submission and completion latencies then measure local time spent sending or
1993 receiving, and the completion latency measures how long it took for the
1994 other end to receive and send back. For UDP multicast traffic
1995 ``pingpong=1`` should only be set for a single reader when multiple readers
1996 are listening to the same address.
1997
e9184ec1 1998.. option:: window_size : [netsplice] [net]
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1999
2000 Set the desired socket buffer size for the connection.
2001
e9184ec1 2002.. option:: mss : [netsplice] [net]
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2003
2004 Set the TCP maximum segment size (TCP_MAXSEG).
2005
2006.. option:: donorname=str : [e4defrag]
2007
730bd7d9 2008 File will be used as a block donor (swap extents between files).
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2009
2010.. option:: inplace=int : [e4defrag]
2011
2012 Configure donor file blocks allocation strategy:
2013
2014 **0**
2015 Default. Preallocate donor's file on init.
2016 **1**
2b455dbf 2017 Allocate space immediately inside defragment event, and free right
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2018 after event.
2019
f3f96717 2020.. option:: clustername=str : [rbd,rados]
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2021
2022 Specifies the name of the Ceph cluster.
2023
2024.. option:: rbdname=str : [rbd]
2025
2026 Specifies the name of the RBD.
2027
f3f96717 2028.. option:: pool=str : [rbd,rados]
f80dba8d 2029
f3f96717 2030 Specifies the name of the Ceph pool containing RBD or RADOS data.
f80dba8d 2031
f3f96717 2032.. option:: clientname=str : [rbd,rados]
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2033
2034 Specifies the username (without the 'client.' prefix) used to access the
2035 Ceph cluster. If the *clustername* is specified, the *clientname* shall be
2036 the full *type.id* string. If no type. prefix is given, fio will add
2037 'client.' by default.
2038
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2039.. option:: busy_poll=bool : [rbd,rados]
2040
2041 Poll store instead of waiting for completion. Usually this provides better
2042 throughput at cost of higher(up to 100%) CPU utilization.
2043
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2044.. option:: skip_bad=bool : [mtd]
2045
2046 Skip operations against known bad blocks.
2047
2048.. option:: hdfsdirectory : [libhdfs]
2049
2050 libhdfs will create chunk in this HDFS directory.
2051
2052.. option:: chunk_size : [libhdfs]
2053
2b455dbf 2054 The size of the chunk to use for each file.
f80dba8d 2055
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2056.. option:: verb=str : [rdma]
2057
2058 The RDMA verb to use on this side of the RDMA ioengine connection. Valid
2059 values are write, read, send and recv. These correspond to the equivalent
2060 RDMA verbs (e.g. write = rdma_write etc.). Note that this only needs to be
2061 specified on the client side of the connection. See the examples folder.
2062
2063.. option:: bindname=str : [rdma]
2064
2065 The name to use to bind the local RDMA-CM connection to a local RDMA device.
2066 This could be a hostname or an IPv4 or IPv6 address. On the server side this
2067 will be passed into the rdma_bind_addr() function and on the client site it
2068 will be used in the rdma_resolve_add() function. This can be useful when
2069 multiple paths exist between the client and the server or in certain loopback
2070 configurations.
f80dba8d 2071
52b81b7c
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2072.. option:: readfua=bool : [sg]
2073
2074 With readfua option set to 1, read operations include
2075 the force unit access (fua) flag. Default is 0.
2076
2077.. option:: writefua=bool : [sg]
2078
2079 With writefua option set to 1, write operations include
2080 the force unit access (fua) flag. Default is 0.
2081
2c3a9150
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2082.. option:: sg_write_mode=str : [sg]
2083 Specify the type of write commands to issue. This option can take three values:
2084
2085 **write**
2086 This is the default where write opcodes are issued as usual.
2087 **verify**
2088 Issue WRITE AND VERIFY commands. The BYTCHK bit is set to 0. This
2089 directs the device to carry out a medium verification with no data
2090 comparison. The writefua option is ignored with this selection.
2091 **same**
2092 Issue WRITE SAME commands. This transfers a single block to the device
2093 and writes this same block of data to a contiguous sequence of LBAs
2094 beginning at the specified offset. fio's block size parameter specifies
2095 the amount of data written with each command. However, the amount of data
2096 actually transferred to the device is equal to the device's block
2097 (sector) size. For a device with 512 byte sectors, blocksize=8k will
2098 write 16 sectors with each command. fio will still generate 8k of data
2099 for each command but only the first 512 bytes will be used and
2100 transferred to the device. The writefua option is ignored with this
2101 selection.
52b81b7c 2102
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2103I/O depth
2104~~~~~~~~~
2105
2106.. option:: iodepth=int
2107
2108 Number of I/O units to keep in flight against the file. Note that
2109 increasing *iodepth* beyond 1 will not affect synchronous ioengines (except
c60ebc45 2110 for small degrees when :option:`verify_async` is in use). Even async
f80dba8d
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2111 engines may impose OS restrictions causing the desired depth not to be
2112 achieved. This may happen on Linux when using libaio and not setting
9207a0cb 2113 :option:`direct`\=1, since buffered I/O is not async on that OS. Keep an
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2114 eye on the I/O depth distribution in the fio output to verify that the
2115 achieved depth is as expected. Default: 1.
2116
2117.. option:: iodepth_batch_submit=int, iodepth_batch=int
2118
2119 This defines how many pieces of I/O to submit at once. It defaults to 1
2120 which means that we submit each I/O as soon as it is available, but can be
2121 raised to submit bigger batches of I/O at the time. If it is set to 0 the
2122 :option:`iodepth` value will be used.
2123
2124.. option:: iodepth_batch_complete_min=int, iodepth_batch_complete=int
2125
2126 This defines how many pieces of I/O to retrieve at once. It defaults to 1
2127 which means that we'll ask for a minimum of 1 I/O in the retrieval process
2128 from the kernel. The I/O retrieval will go on until we hit the limit set by
2129 :option:`iodepth_low`. If this variable is set to 0, then fio will always
2130 check for completed events before queuing more I/O. This helps reduce I/O
2131 latency, at the cost of more retrieval system calls.
2132
2133.. option:: iodepth_batch_complete_max=int
2134
2135 This defines maximum pieces of I/O to retrieve at once. This variable should
9207a0cb 2136 be used along with :option:`iodepth_batch_complete_min`\=int variable,
f80dba8d 2137 specifying the range of min and max amount of I/O which should be
730bd7d9 2138 retrieved. By default it is equal to the :option:`iodepth_batch_complete_min`
f80dba8d
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2139 value.
2140
2141 Example #1::
2142
2143 iodepth_batch_complete_min=1
2144 iodepth_batch_complete_max=<iodepth>
2145
2146 which means that we will retrieve at least 1 I/O and up to the whole
2147 submitted queue depth. If none of I/O has been completed yet, we will wait.
2148
2149 Example #2::
2150
2151 iodepth_batch_complete_min=0
2152 iodepth_batch_complete_max=<iodepth>
2153
2154 which means that we can retrieve up to the whole submitted queue depth, but
2155 if none of I/O has been completed yet, we will NOT wait and immediately exit
2156 the system call. In this example we simply do polling.
2157
2158.. option:: iodepth_low=int
2159
2160 The low water mark indicating when to start filling the queue
2161 again. Defaults to the same as :option:`iodepth`, meaning that fio will
2162 attempt to keep the queue full at all times. If :option:`iodepth` is set to
c60ebc45 2163 e.g. 16 and *iodepth_low* is set to 4, then after fio has filled the queue of
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2164 16 requests, it will let the depth drain down to 4 before starting to fill
2165 it again.
2166
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2167.. option:: serialize_overlap=bool
2168
2169 Serialize in-flight I/Os that might otherwise cause or suffer from data races.
2170 When two or more I/Os are submitted simultaneously, there is no guarantee that
2171 the I/Os will be processed or completed in the submitted order. Further, if
2172 two or more of those I/Os are writes, any overlapping region between them can
2173 become indeterminate/undefined on certain storage. These issues can cause
2174 verification to fail erratically when at least one of the racing I/Os is
2175 changing data and the overlapping region has a non-zero size. Setting
2176 ``serialize_overlap`` tells fio to avoid provoking this behavior by explicitly
2177 serializing in-flight I/Os that have a non-zero overlap. Note that setting
ee21ebee 2178 this option can reduce both performance and the :option:`iodepth` achieved.
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2179 Additionally this option does not work when :option:`io_submit_mode` is set to
2180 offload. Default: false.
2181
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2182.. option:: io_submit_mode=str
2183
2184 This option controls how fio submits the I/O to the I/O engine. The default
2185 is `inline`, which means that the fio job threads submit and reap I/O
2186 directly. If set to `offload`, the job threads will offload I/O submission
2187 to a dedicated pool of I/O threads. This requires some coordination and thus
2188 has a bit of extra overhead, especially for lower queue depth I/O where it
2189 can increase latencies. The benefit is that fio can manage submission rates
2190 independently of the device completion rates. This avoids skewed latency
730bd7d9 2191 reporting if I/O gets backed up on the device side (the coordinated omission
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2192 problem).
2193
2194
2195I/O rate
2196~~~~~~~~
2197
a881438b 2198.. option:: thinktime=time
f80dba8d 2199
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2200 Stall the job for the specified period of time after an I/O has completed before issuing the
2201 next. May be used to simulate processing being done by an application.
947e0fe0 2202 When the unit is omitted, the value is interpreted in microseconds. See
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2203 :option:`thinktime_blocks` and :option:`thinktime_spin`.
2204
a881438b 2205.. option:: thinktime_spin=time
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2206
2207 Only valid if :option:`thinktime` is set - pretend to spend CPU time doing
2208 something with the data received, before falling back to sleeping for the
f75ede1d 2209 rest of the period specified by :option:`thinktime`. When the unit is
947e0fe0 2210 omitted, the value is interpreted in microseconds.
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2211
2212.. option:: thinktime_blocks=int
2213
2214 Only valid if :option:`thinktime` is set - control how many blocks to issue,
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2215 before waiting :option:`thinktime` usecs. If not set, defaults to 1 which will make
2216 fio wait :option:`thinktime` usecs after every block. This effectively makes any
f80dba8d 2217 queue depth setting redundant, since no more than 1 I/O will be queued
f50fbdda 2218 before we have to complete it and do our :option:`thinktime`. In other words, this
f80dba8d 2219 setting effectively caps the queue depth if the latter is larger.
71bfa161 2220
f80dba8d 2221.. option:: rate=int[,int][,int]
71bfa161 2222
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2223 Cap the bandwidth used by this job. The number is in bytes/sec, the normal
2224 suffix rules apply. Comma-separated values may be specified for reads,
2225 writes, and trims as described in :option:`blocksize`.
71bfa161 2226
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2227 For example, using `rate=1m,500k` would limit reads to 1MiB/sec and writes to
2228 500KiB/sec. Capping only reads or writes can be done with `rate=,500k` or
2229 `rate=500k,` where the former will only limit writes (to 500KiB/sec) and the
2230 latter will only limit reads.
2231
f80dba8d 2232.. option:: rate_min=int[,int][,int]
71bfa161 2233
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2234 Tell fio to do whatever it can to maintain at least this bandwidth. Failing
2235 to meet this requirement will cause the job to exit. Comma-separated values
2236 may be specified for reads, writes, and trims as described in
2237 :option:`blocksize`.
71bfa161 2238
f80dba8d 2239.. option:: rate_iops=int[,int][,int]
71bfa161 2240
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2241 Cap the bandwidth to this number of IOPS. Basically the same as
2242 :option:`rate`, just specified independently of bandwidth. If the job is
2243 given a block size range instead of a fixed value, the smallest block size
2244 is used as the metric. Comma-separated values may be specified for reads,
2245 writes, and trims as described in :option:`blocksize`.
71bfa161 2246
f80dba8d 2247.. option:: rate_iops_min=int[,int][,int]
71bfa161 2248
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2249 If fio doesn't meet this rate of I/O, it will cause the job to exit.
2250 Comma-separated values may be specified for reads, writes, and trims as
2251 described in :option:`blocksize`.
71bfa161 2252
f80dba8d 2253.. option:: rate_process=str
66c098b8 2254
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2255 This option controls how fio manages rated I/O submissions. The default is
2256 `linear`, which submits I/O in a linear fashion with fixed delays between
c60ebc45 2257 I/Os that gets adjusted based on I/O completion rates. If this is set to
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2258 `poisson`, fio will submit I/O based on a more real world random request
2259 flow, known as the Poisson process
2260 (https://en.wikipedia.org/wiki/Poisson_point_process). The lambda will be
2261 10^6 / IOPS for the given workload.
71bfa161 2262
1a9bf814
JA
2263.. option:: rate_ignore_thinktime=bool
2264
2265 By default, fio will attempt to catch up to the specified rate setting,
2266 if any kind of thinktime setting was used. If this option is set, then
2267 fio will ignore the thinktime and continue doing IO at the specified
2268 rate, instead of entering a catch-up mode after thinktime is done.
2269
71bfa161 2270
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2271I/O latency
2272~~~~~~~~~~~
71bfa161 2273
a881438b 2274.. option:: latency_target=time
71bfa161 2275
f80dba8d 2276 If set, fio will attempt to find the max performance point that the given
f75ede1d 2277 workload will run at while maintaining a latency below this target. When
947e0fe0 2278 the unit is omitted, the value is interpreted in microseconds. See
f75ede1d 2279 :option:`latency_window` and :option:`latency_percentile`.
71bfa161 2280
a881438b 2281.. option:: latency_window=time
71bfa161 2282
f80dba8d 2283 Used with :option:`latency_target` to specify the sample window that the job
f75ede1d 2284 is run at varying queue depths to test the performance. When the unit is
947e0fe0 2285 omitted, the value is interpreted in microseconds.
b4692828 2286
f80dba8d 2287.. option:: latency_percentile=float
71bfa161 2288
c60ebc45 2289 The percentage of I/Os that must fall within the criteria specified by
f80dba8d 2290 :option:`latency_target` and :option:`latency_window`. If not set, this
c60ebc45 2291 defaults to 100.0, meaning that all I/Os must be equal or below to the value
f80dba8d 2292 set by :option:`latency_target`.
71bfa161 2293
a881438b 2294.. option:: max_latency=time
71bfa161 2295
f75ede1d 2296 If set, fio will exit the job with an ETIMEDOUT error if it exceeds this
947e0fe0 2297 maximum latency. When the unit is omitted, the value is interpreted in
f75ede1d 2298 microseconds.
71bfa161 2299
f80dba8d 2300.. option:: rate_cycle=int
71bfa161 2301
f80dba8d 2302 Average bandwidth for :option:`rate` and :option:`rate_min` over this number
a47b697c 2303 of milliseconds. Defaults to 1000.
71bfa161 2304
71bfa161 2305
f80dba8d
MT
2306I/O replay
2307~~~~~~~~~~
71bfa161 2308
f80dba8d 2309.. option:: write_iolog=str
c2b1e753 2310
f80dba8d
MT
2311 Write the issued I/O patterns to the specified file. See
2312 :option:`read_iolog`. Specify a separate file for each job, otherwise the
2313 iologs will be interspersed and the file may be corrupt.
c2b1e753 2314
f80dba8d 2315.. option:: read_iolog=str
71bfa161 2316
22413915 2317 Open an iolog with the specified filename and replay the I/O patterns it
f80dba8d
MT
2318 contains. This can be used to store a workload and replay it sometime
2319 later. The iolog given may also be a blktrace binary file, which allows fio
2320 to replay a workload captured by :command:`blktrace`. See
2321 :manpage:`blktrace(8)` for how to capture such logging data. For blktrace
2322 replay, the file needs to be turned into a blkparse binary data file first
2323 (``blkparse <device> -o /dev/null -d file_for_fio.bin``).
71bfa161 2324
589e88b7 2325.. option:: replay_no_stall=bool
71bfa161 2326
f80dba8d 2327 When replaying I/O with :option:`read_iolog` the default behavior is to
22413915 2328 attempt to respect the timestamps within the log and replay them with the
f80dba8d
MT
2329 appropriate delay between IOPS. By setting this variable fio will not
2330 respect the timestamps and attempt to replay them as fast as possible while
2331 still respecting ordering. The result is the same I/O pattern to a given
2332 device, but different timings.
71bfa161 2333
6dd7fa77
JA
2334.. option:: replay_time_scale=int
2335
2336 When replaying I/O with :option:`read_iolog`, fio will honor the
2337 original timing in the trace. With this option, it's possible to scale
2338 the time. It's a percentage option, if set to 50 it means run at 50%
2339 the original IO rate in the trace. If set to 200, run at twice the
2340 original IO rate. Defaults to 100.
2341
f80dba8d 2342.. option:: replay_redirect=str
b4692828 2343
f80dba8d
MT
2344 While replaying I/O patterns using :option:`read_iolog` the default behavior
2345 is to replay the IOPS onto the major/minor device that each IOP was recorded
2346 from. This is sometimes undesirable because on a different machine those
2347 major/minor numbers can map to a different device. Changing hardware on the
2348 same system can also result in a different major/minor mapping.
730bd7d9 2349 ``replay_redirect`` causes all I/Os to be replayed onto the single specified
f80dba8d 2350 device regardless of the device it was recorded
9207a0cb 2351 from. i.e. :option:`replay_redirect`\= :file:`/dev/sdc` would cause all I/O
f80dba8d
MT
2352 in the blktrace or iolog to be replayed onto :file:`/dev/sdc`. This means
2353 multiple devices will be replayed onto a single device, if the trace
2354 contains multiple devices. If you want multiple devices to be replayed
2355 concurrently to multiple redirected devices you must blkparse your trace
2356 into separate traces and replay them with independent fio invocations.
2357 Unfortunately this also breaks the strict time ordering between multiple
2358 device accesses.
71bfa161 2359
f80dba8d 2360.. option:: replay_align=int
74929ac2 2361
f80dba8d
MT
2362 Force alignment of I/O offsets and lengths in a trace to this power of 2
2363 value.
3c54bc46 2364
f80dba8d 2365.. option:: replay_scale=int
3c54bc46 2366
f80dba8d 2367 Scale sector offsets down by this factor when replaying traces.
3c54bc46 2368
38f68906
JA
2369.. option:: replay_skip=str
2370
2371 Sometimes it's useful to skip certain IO types in a replay trace.
2372 This could be, for instance, eliminating the writes in the trace.
2373 Or not replaying the trims/discards, if you are redirecting to
2374 a device that doesn't support them. This option takes a comma
2375 separated list of read, write, trim, sync.
2376
3c54bc46 2377
f80dba8d
MT
2378Threads, processes and job synchronization
2379~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3c54bc46 2380
f80dba8d 2381.. option:: thread
3c54bc46 2382
730bd7d9
SW
2383 Fio defaults to creating jobs by using fork, however if this option is
2384 given, fio will create jobs by using POSIX Threads' function
2385 :manpage:`pthread_create(3)` to create threads instead.
71bfa161 2386
f80dba8d 2387.. option:: wait_for=str
74929ac2 2388
730bd7d9
SW
2389 If set, the current job won't be started until all workers of the specified
2390 waitee job are done.
74929ac2 2391
f80dba8d
MT
2392 ``wait_for`` operates on the job name basis, so there are a few
2393 limitations. First, the waitee must be defined prior to the waiter job
2394 (meaning no forward references). Second, if a job is being referenced as a
2395 waitee, it must have a unique name (no duplicate waitees).
74929ac2 2396
f80dba8d 2397.. option:: nice=int
892a6ffc 2398
f80dba8d 2399 Run the job with the given nice value. See man :manpage:`nice(2)`.
892a6ffc 2400
f80dba8d
MT
2401 On Windows, values less than -15 set the process class to "High"; -1 through
2402 -15 set "Above Normal"; 1 through 15 "Below Normal"; and above 15 "Idle"
2403 priority class.
74929ac2 2404
f80dba8d 2405.. option:: prio=int
71bfa161 2406
f80dba8d
MT
2407 Set the I/O priority value of this job. Linux limits us to a positive value
2408 between 0 and 7, with 0 being the highest. See man
2409 :manpage:`ionice(1)`. Refer to an appropriate manpage for other operating
2410 systems since meaning of priority may differ.
71bfa161 2411
f80dba8d 2412.. option:: prioclass=int
d59aa780 2413
f80dba8d 2414 Set the I/O priority class. See man :manpage:`ionice(1)`.
d59aa780 2415
f80dba8d 2416.. option:: cpus_allowed=str
6d500c2e 2417
730bd7d9 2418 Controls the same options as :option:`cpumask`, but accepts a textual
b570e037
SW
2419 specification of the permitted CPUs instead and CPUs are indexed from 0. So
2420 to use CPUs 0 and 5 you would specify ``cpus_allowed=0,5``. This option also
2421 allows a range of CPUs to be specified -- say you wanted a binding to CPUs
2422 0, 5, and 8 to 15, you would set ``cpus_allowed=0,5,8-15``.
2423
2424 On Windows, when ``cpus_allowed`` is unset only CPUs from fio's current
2425 processor group will be used and affinity settings are inherited from the
2426 system. An fio build configured to target Windows 7 makes options that set
2427 CPUs processor group aware and values will set both the processor group
2428 and a CPU from within that group. For example, on a system where processor
2429 group 0 has 40 CPUs and processor group 1 has 32 CPUs, ``cpus_allowed``
2430 values between 0 and 39 will bind CPUs from processor group 0 and
2431 ``cpus_allowed`` values between 40 and 71 will bind CPUs from processor
2432 group 1. When using ``cpus_allowed_policy=shared`` all CPUs specified by a
2433 single ``cpus_allowed`` option must be from the same processor group. For
2434 Windows fio builds not built for Windows 7, CPUs will only be selected from
2435 (and be relative to) whatever processor group fio happens to be running in
2436 and CPUs from other processor groups cannot be used.
6d500c2e 2437
f80dba8d 2438.. option:: cpus_allowed_policy=str
6d500c2e 2439
f80dba8d 2440 Set the policy of how fio distributes the CPUs specified by
730bd7d9 2441 :option:`cpus_allowed` or :option:`cpumask`. Two policies are supported:
6d500c2e 2442
f80dba8d
MT
2443 **shared**
2444 All jobs will share the CPU set specified.
2445 **split**
2446 Each job will get a unique CPU from the CPU set.
6d500c2e 2447
22413915 2448 **shared** is the default behavior, if the option isn't specified. If
f80dba8d
MT
2449 **split** is specified, then fio will will assign one cpu per job. If not
2450 enough CPUs are given for the jobs listed, then fio will roundrobin the CPUs
2451 in the set.
6d500c2e 2452
b570e037
SW
2453.. option:: cpumask=int
2454
2455 Set the CPU affinity of this job. The parameter given is a bit mask of
2456 allowed CPUs the job may run on. So if you want the allowed CPUs to be 1
2457 and 5, you would pass the decimal value of (1 << 1 | 1 << 5), or 34. See man
2458 :manpage:`sched_setaffinity(2)`. This may not work on all supported
2459 operating systems or kernel versions. This option doesn't work well for a
2460 higher CPU count than what you can store in an integer mask, so it can only
2461 control cpus 1-32. For boxes with larger CPU counts, use
2462 :option:`cpus_allowed`.
2463
f80dba8d 2464.. option:: numa_cpu_nodes=str
6d500c2e 2465
f80dba8d
MT
2466 Set this job running on specified NUMA nodes' CPUs. The arguments allow
2467 comma delimited list of cpu numbers, A-B ranges, or `all`. Note, to enable
ac8ca2af 2468 NUMA options support, fio must be built on a system with libnuma-dev(el)
f80dba8d 2469 installed.
61b9861d 2470
f80dba8d 2471.. option:: numa_mem_policy=str
61b9861d 2472
f80dba8d
MT
2473 Set this job's memory policy and corresponding NUMA nodes. Format of the
2474 arguments::
5c94b008 2475
f80dba8d 2476 <mode>[:<nodelist>]
ce35b1ec 2477
804c0839 2478 ``mode`` is one of the following memory policies: ``default``, ``prefer``,
730bd7d9
SW
2479 ``bind``, ``interleave`` or ``local``. For ``default`` and ``local`` memory
2480 policies, no node needs to be specified. For ``prefer``, only one node is
2481 allowed. For ``bind`` and ``interleave`` the ``nodelist`` may be as
2482 follows: a comma delimited list of numbers, A-B ranges, or `all`.
71bfa161 2483
f80dba8d 2484.. option:: cgroup=str
390b1537 2485
f80dba8d
MT
2486 Add job to this control group. If it doesn't exist, it will be created. The
2487 system must have a mounted cgroup blkio mount point for this to work. If
2488 your system doesn't have it mounted, you can do so with::
5af1c6f3 2489
f80dba8d 2490 # mount -t cgroup -o blkio none /cgroup
5af1c6f3 2491
f80dba8d 2492.. option:: cgroup_weight=int
5af1c6f3 2493
f80dba8d
MT
2494 Set the weight of the cgroup to this value. See the documentation that comes
2495 with the kernel, allowed values are in the range of 100..1000.
a086c257 2496
f80dba8d 2497.. option:: cgroup_nodelete=bool
8c07860d 2498
f80dba8d
MT
2499 Normally fio will delete the cgroups it has created after the job
2500 completion. To override this behavior and to leave cgroups around after the
2501 job completion, set ``cgroup_nodelete=1``. This can be useful if one wants
2502 to inspect various cgroup files after job completion. Default: false.
8c07860d 2503
f80dba8d 2504.. option:: flow_id=int
8c07860d 2505
f80dba8d
MT
2506 The ID of the flow. If not specified, it defaults to being a global
2507 flow. See :option:`flow`.
1907dbc6 2508
f80dba8d 2509.. option:: flow=int
71bfa161 2510
f80dba8d
MT
2511 Weight in token-based flow control. If this value is used, then there is a
2512 'flow counter' which is used to regulate the proportion of activity between
2513 two or more jobs. Fio attempts to keep this flow counter near zero. The
2514 ``flow`` parameter stands for how much should be added or subtracted to the
2515 flow counter on each iteration of the main I/O loop. That is, if one job has
2516 ``flow=8`` and another job has ``flow=-1``, then there will be a roughly 1:8
2517 ratio in how much one runs vs the other.
71bfa161 2518
f80dba8d 2519.. option:: flow_watermark=int
a31041ea 2520
f80dba8d
MT
2521 The maximum value that the absolute value of the flow counter is allowed to
2522 reach before the job must wait for a lower value of the counter.
82407585 2523
f80dba8d 2524.. option:: flow_sleep=int
82407585 2525
f80dba8d
MT
2526 The period of time, in microseconds, to wait after the flow watermark has
2527 been exceeded before retrying operations.
82407585 2528
f80dba8d 2529.. option:: stonewall, wait_for_previous
82407585 2530
f80dba8d
MT
2531 Wait for preceding jobs in the job file to exit, before starting this
2532 one. Can be used to insert serialization points in the job file. A stone
2533 wall also implies starting a new reporting group, see
2534 :option:`group_reporting`.
2535
2536.. option:: exitall
2537
730bd7d9
SW
2538 By default, fio will continue running all other jobs when one job finishes
2539 but sometimes this is not the desired action. Setting ``exitall`` will
2540 instead make fio terminate all other jobs when one job finishes.
f80dba8d
MT
2541
2542.. option:: exec_prerun=str
2543
2544 Before running this job, issue the command specified through
2545 :manpage:`system(3)`. Output is redirected in a file called
2546 :file:`jobname.prerun.txt`.
2547
2548.. option:: exec_postrun=str
2549
2550 After the job completes, issue the command specified though
2551 :manpage:`system(3)`. Output is redirected in a file called
2552 :file:`jobname.postrun.txt`.
2553
2554.. option:: uid=int
2555
2556 Instead of running as the invoking user, set the user ID to this value
2557 before the thread/process does any work.
2558
2559.. option:: gid=int
2560
2561 Set group ID, see :option:`uid`.
2562
2563
2564Verification
2565~~~~~~~~~~~~
2566
2567.. option:: verify_only
2568
2569 Do not perform specified workload, only verify data still matches previous
2570 invocation of this workload. This option allows one to check data multiple
2571 times at a later date without overwriting it. This option makes sense only
2572 for workloads that write data, and does not support workloads with the
2573 :option:`time_based` option set.
2574
2575.. option:: do_verify=bool
2576
2577 Run the verify phase after a write phase. Only valid if :option:`verify` is
2578 set. Default: true.
2579
2580.. option:: verify=str
2581
2582 If writing to a file, fio can verify the file contents after each iteration
2583 of the job. Each verification method also implies verification of special
2584 header, which is written to the beginning of each block. This header also
2585 includes meta information, like offset of the block, block number, timestamp
2586 when block was written, etc. :option:`verify` can be combined with
2587 :option:`verify_pattern` option. The allowed values are:
2588
2589 **md5**
2590 Use an md5 sum of the data area and store it in the header of
2591 each block.
2592
2593 **crc64**
2594 Use an experimental crc64 sum of the data area and store it in the
2595 header of each block.
2596
2597 **crc32c**
a5896300
SW
2598 Use a crc32c sum of the data area and store it in the header of
2599 each block. This will automatically use hardware acceleration
2600 (e.g. SSE4.2 on an x86 or CRC crypto extensions on ARM64) but will
2601 fall back to software crc32c if none is found. Generally the
804c0839 2602 fastest checksum fio supports when hardware accelerated.
f80dba8d
MT
2603
2604 **crc32c-intel**
a5896300 2605 Synonym for crc32c.
f80dba8d
MT
2606
2607 **crc32**
2608 Use a crc32 sum of the data area and store it in the header of each
2609 block.
2610
2611 **crc16**
2612 Use a crc16 sum of the data area and store it in the header of each
2613 block.
2614
2615 **crc7**
2616 Use a crc7 sum of the data area and store it in the header of each
2617 block.
2618
2619 **xxhash**
2620 Use xxhash as the checksum function. Generally the fastest software
2621 checksum that fio supports.
2622
2623 **sha512**
2624 Use sha512 as the checksum function.
2625
2626 **sha256**
2627 Use sha256 as the checksum function.
2628
2629 **sha1**
2630 Use optimized sha1 as the checksum function.
82407585 2631
ae3a5acc
JA
2632 **sha3-224**
2633 Use optimized sha3-224 as the checksum function.
2634
2635 **sha3-256**
2636 Use optimized sha3-256 as the checksum function.
2637
2638 **sha3-384**
2639 Use optimized sha3-384 as the checksum function.
2640
2641 **sha3-512**
2642 Use optimized sha3-512 as the checksum function.
2643
f80dba8d
MT
2644 **meta**
2645 This option is deprecated, since now meta information is included in
2646 generic verification header and meta verification happens by
2647 default. For detailed information see the description of the
2648 :option:`verify` setting. This option is kept because of
2649 compatibility's sake with old configurations. Do not use it.
2650
2651 **pattern**
2652 Verify a strict pattern. Normally fio includes a header with some
2653 basic information and checksumming, but if this option is set, only
2654 the specific pattern set with :option:`verify_pattern` is verified.
2655
2656 **null**
2657 Only pretend to verify. Useful for testing internals with
9207a0cb 2658 :option:`ioengine`\=null, not for much else.
f80dba8d
MT
2659
2660 This option can be used for repeated burn-in tests of a system to make sure
2661 that the written data is also correctly read back. If the data direction
2662 given is a read or random read, fio will assume that it should verify a
2663 previously written file. If the data direction includes any form of write,
2664 the verify will be of the newly written data.
2665
f80dba8d
MT
2666.. option:: verify_offset=int
2667
2668 Swap the verification header with data somewhere else in the block before
2669 writing. It is swapped back before verifying.
2670
2671.. option:: verify_interval=int
2672
2673 Write the verification header at a finer granularity than the
2674 :option:`blocksize`. It will be written for chunks the size of
2675 ``verify_interval``. :option:`blocksize` should divide this evenly.
2676
2677.. option:: verify_pattern=str
2678
2679 If set, fio will fill the I/O buffers with this pattern. Fio defaults to
2680 filling with totally random bytes, but sometimes it's interesting to fill
2681 with a known pattern for I/O verification purposes. Depending on the width
730bd7d9 2682 of the pattern, fio will fill 1/2/3/4 bytes of the buffer at the time (it can
f80dba8d
MT
2683 be either a decimal or a hex number). The ``verify_pattern`` if larger than
2684 a 32-bit quantity has to be a hex number that starts with either "0x" or
2685 "0X". Use with :option:`verify`. Also, ``verify_pattern`` supports %o
2686 format, which means that for each block offset will be written and then
2687 verified back, e.g.::
61b9861d
RP
2688
2689 verify_pattern=%o
2690
f80dba8d
MT
2691 Or use combination of everything::
2692
61b9861d 2693 verify_pattern=0xff%o"abcd"-12
e28218f3 2694
f80dba8d
MT
2695.. option:: verify_fatal=bool
2696
2697 Normally fio will keep checking the entire contents before quitting on a
2698 block verification failure. If this option is set, fio will exit the job on
2699 the first observed failure. Default: false.
2700
2701.. option:: verify_dump=bool
2702
2703 If set, dump the contents of both the original data block and the data block
2704 we read off disk to files. This allows later analysis to inspect just what
2705 kind of data corruption occurred. Off by default.
2706
2707.. option:: verify_async=int
2708
2709 Fio will normally verify I/O inline from the submitting thread. This option
2710 takes an integer describing how many async offload threads to create for I/O
2711 verification instead, causing fio to offload the duty of verifying I/O
2712 contents to one or more separate threads. If using this offload option, even
2713 sync I/O engines can benefit from using an :option:`iodepth` setting higher
2714 than 1, as it allows them to have I/O in flight while verifies are running.
d7e6ea1c 2715 Defaults to 0 async threads, i.e. verification is not asynchronous.
f80dba8d
MT
2716
2717.. option:: verify_async_cpus=str
2718
2719 Tell fio to set the given CPU affinity on the async I/O verification
2720 threads. See :option:`cpus_allowed` for the format used.
2721
2722.. option:: verify_backlog=int
2723
2724 Fio will normally verify the written contents of a job that utilizes verify
2725 once that job has completed. In other words, everything is written then
2726 everything is read back and verified. You may want to verify continually
2727 instead for a variety of reasons. Fio stores the meta data associated with
2728 an I/O block in memory, so for large verify workloads, quite a bit of memory
2729 would be used up holding this meta data. If this option is enabled, fio will
2730 write only N blocks before verifying these blocks.
2731
2732.. option:: verify_backlog_batch=int
2733
2734 Control how many blocks fio will verify if :option:`verify_backlog` is
2735 set. If not set, will default to the value of :option:`verify_backlog`
2736 (meaning the entire queue is read back and verified). If
2737 ``verify_backlog_batch`` is less than :option:`verify_backlog` then not all
2738 blocks will be verified, if ``verify_backlog_batch`` is larger than
2739 :option:`verify_backlog`, some blocks will be verified more than once.
2740
2741.. option:: verify_state_save=bool
2742
2743 When a job exits during the write phase of a verify workload, save its
2744 current state. This allows fio to replay up until that point, if the verify
2745 state is loaded for the verify read phase. The format of the filename is,
2746 roughly::
2747
f50fbdda 2748 <type>-<jobname>-<jobindex>-verify.state.
f80dba8d
MT
2749
2750 <type> is "local" for a local run, "sock" for a client/server socket
2751 connection, and "ip" (192.168.0.1, for instance) for a networked
d7e6ea1c 2752 client/server connection. Defaults to true.
f80dba8d
MT
2753
2754.. option:: verify_state_load=bool
2755
2756 If a verify termination trigger was used, fio stores the current write state
2757 of each thread. This can be used at verification time so that fio knows how
2758 far it should verify. Without this information, fio will run a full
a47b697c
SW
2759 verification pass, according to the settings in the job file used. Default
2760 false.
f80dba8d
MT
2761
2762.. option:: trim_percentage=int
2763
2764 Number of verify blocks to discard/trim.
2765
2766.. option:: trim_verify_zero=bool
2767
22413915 2768 Verify that trim/discarded blocks are returned as zeros.
f80dba8d
MT
2769
2770.. option:: trim_backlog=int
2771
5cfd1e9a 2772 Trim after this number of blocks are written.
f80dba8d
MT
2773
2774.. option:: trim_backlog_batch=int
2775
2776 Trim this number of I/O blocks.
2777
2778.. option:: experimental_verify=bool
2779
2780 Enable experimental verification.
2781
f80dba8d
MT
2782Steady state
2783~~~~~~~~~~~~
2784
2785.. option:: steadystate=str:float, ss=str:float
2786
2787 Define the criterion and limit for assessing steady state performance. The
2788 first parameter designates the criterion whereas the second parameter sets
2789 the threshold. When the criterion falls below the threshold for the
2790 specified duration, the job will stop. For example, `iops_slope:0.1%` will
2791 direct fio to terminate the job when the least squares regression slope
2792 falls below 0.1% of the mean IOPS. If :option:`group_reporting` is enabled
2793 this will apply to all jobs in the group. Below is the list of available
2794 steady state assessment criteria. All assessments are carried out using only
2795 data from the rolling collection window. Threshold limits can be expressed
2796 as a fixed value or as a percentage of the mean in the collection window.
2797
2798 **iops**
2799 Collect IOPS data. Stop the job if all individual IOPS measurements
2800 are within the specified limit of the mean IOPS (e.g., ``iops:2``
2801 means that all individual IOPS values must be within 2 of the mean,
2802 whereas ``iops:0.2%`` means that all individual IOPS values must be
2803 within 0.2% of the mean IOPS to terminate the job).
2804
2805 **iops_slope**
2806 Collect IOPS data and calculate the least squares regression
2807 slope. Stop the job if the slope falls below the specified limit.
2808
2809 **bw**
2810 Collect bandwidth data. Stop the job if all individual bandwidth
2811 measurements are within the specified limit of the mean bandwidth.
2812
2813 **bw_slope**
2814 Collect bandwidth data and calculate the least squares regression
2815 slope. Stop the job if the slope falls below the specified limit.
2816
2817.. option:: steadystate_duration=time, ss_dur=time
2818
2819 A rolling window of this duration will be used to judge whether steady state
2820 has been reached. Data will be collected once per second. The default is 0
f75ede1d 2821 which disables steady state detection. When the unit is omitted, the
947e0fe0 2822 value is interpreted in seconds.
f80dba8d
MT
2823
2824.. option:: steadystate_ramp_time=time, ss_ramp=time
2825
2826 Allow the job to run for the specified duration before beginning data
2827 collection for checking the steady state job termination criterion. The
947e0fe0 2828 default is 0. When the unit is omitted, the value is interpreted in seconds.
f80dba8d
MT
2829
2830
2831Measurements and reporting
2832~~~~~~~~~~~~~~~~~~~~~~~~~~
2833
2834.. option:: per_job_logs=bool
2835
2836 If set, this generates bw/clat/iops log with per file private filenames. If
2837 not set, jobs with identical names will share the log filename. Default:
2838 true.
2839
2840.. option:: group_reporting
2841
2842 It may sometimes be interesting to display statistics for groups of jobs as
2843 a whole instead of for each individual job. This is especially true if
2844 :option:`numjobs` is used; looking at individual thread/process output
2845 quickly becomes unwieldy. To see the final report per-group instead of
2846 per-job, use :option:`group_reporting`. Jobs in a file will be part of the
2847 same reporting group, unless if separated by a :option:`stonewall`, or by
2848 using :option:`new_group`.
2849
2850.. option:: new_group
2851
2852 Start a new reporting group. See: :option:`group_reporting`. If not given,
2853 all jobs in a file will be part of the same reporting group, unless
2854 separated by a :option:`stonewall`.
2855
589e88b7 2856.. option:: stats=bool
8243be59
JA
2857
2858 By default, fio collects and shows final output results for all jobs
2859 that run. If this option is set to 0, then fio will ignore it in
2860 the final stat output.
2861
f80dba8d
MT
2862.. option:: write_bw_log=str
2863
2864 If given, write a bandwidth log for this job. Can be used to store data of
074f0817 2865 the bandwidth of the jobs in their lifetime.
f80dba8d 2866
074f0817
SW
2867 If no str argument is given, the default filename of
2868 :file:`jobname_type.x.log` is used. Even when the argument is given, fio
2869 will still append the type of log. So if one specifies::
2870
2871 write_bw_log=foo
f80dba8d 2872
074f0817
SW
2873 The actual log name will be :file:`foo_bw.x.log` where `x` is the index
2874 of the job (`1..N`, where `N` is the number of jobs). If
2875 :option:`per_job_logs` is false, then the filename will not include the
2876 `.x` job index.
e3cedca7 2877
074f0817
SW
2878 The included :command:`fio_generate_plots` script uses :command:`gnuplot` to turn these
2879 text files into nice graphs. See `Log File Formats`_ for how data is
2880 structured within the file.
2881
2882.. option:: write_lat_log=str
e3cedca7 2883
074f0817 2884 Same as :option:`write_bw_log`, except this option creates I/O
77b7e675
SW
2885 submission (e.g., :file:`name_slat.x.log`), completion (e.g.,
2886 :file:`name_clat.x.log`), and total (e.g., :file:`name_lat.x.log`)
074f0817
SW
2887 latency files instead. See :option:`write_bw_log` for details about
2888 the filename format and `Log File Formats`_ for how data is structured
2889 within the files.
be4ecfdf 2890
f80dba8d 2891.. option:: write_hist_log=str
06842027 2892
074f0817 2893 Same as :option:`write_bw_log` but writes an I/O completion latency
77b7e675 2894 histogram file (e.g., :file:`name_hist.x.log`) instead. Note that this
074f0817
SW
2895 file will be empty unless :option:`log_hist_msec` has also been set.
2896 See :option:`write_bw_log` for details about the filename format and
2897 `Log File Formats`_ for how data is structured within the file.
06842027 2898
f80dba8d 2899.. option:: write_iops_log=str
06842027 2900
074f0817 2901 Same as :option:`write_bw_log`, but writes an IOPS file (e.g.
77b7e675 2902 :file:`name_iops.x.log`) instead. See :option:`write_bw_log` for
074f0817
SW
2903 details about the filename format and `Log File Formats`_ for how data
2904 is structured within the file.
06842027 2905
f80dba8d 2906.. option:: log_avg_msec=int
06842027 2907
f80dba8d
MT
2908 By default, fio will log an entry in the iops, latency, or bw log for every
2909 I/O that completes. When writing to the disk log, that can quickly grow to a
2910 very large size. Setting this option makes fio average the each log entry
2911 over the specified period of time, reducing the resolution of the log. See
2912 :option:`log_max_value` as well. Defaults to 0, logging all entries.
6fc82095 2913 Also see `Log File Formats`_.
06842027 2914
f80dba8d 2915.. option:: log_hist_msec=int
06842027 2916
f80dba8d
MT
2917 Same as :option:`log_avg_msec`, but logs entries for completion latency
2918 histograms. Computing latency percentiles from averages of intervals using
c60ebc45 2919 :option:`log_avg_msec` is inaccurate. Setting this option makes fio log
f80dba8d
MT
2920 histogram entries over the specified period of time, reducing log sizes for
2921 high IOPS devices while retaining percentile accuracy. See
074f0817
SW
2922 :option:`log_hist_coarseness` and :option:`write_hist_log` as well.
2923 Defaults to 0, meaning histogram logging is disabled.
06842027 2924
f80dba8d 2925.. option:: log_hist_coarseness=int
06842027 2926
f80dba8d
MT
2927 Integer ranging from 0 to 6, defining the coarseness of the resolution of
2928 the histogram logs enabled with :option:`log_hist_msec`. For each increment
2929 in coarseness, fio outputs half as many bins. Defaults to 0, for which
074f0817
SW
2930 histogram logs contain 1216 latency bins. See :option:`write_hist_log`
2931 and `Log File Formats`_.
8b28bd41 2932
f80dba8d 2933.. option:: log_max_value=bool
66c098b8 2934
f80dba8d
MT
2935 If :option:`log_avg_msec` is set, fio logs the average over that window. If
2936 you instead want to log the maximum value, set this option to 1. Defaults to
2937 0, meaning that averaged values are logged.
a696fa2a 2938
589e88b7 2939.. option:: log_offset=bool
a696fa2a 2940
f80dba8d 2941 If this is set, the iolog options will include the byte offset for the I/O
5a83478f
SW
2942 entry as well as the other data values. Defaults to 0 meaning that
2943 offsets are not present in logs. Also see `Log File Formats`_.
71bfa161 2944
f80dba8d 2945.. option:: log_compression=int
7de87099 2946
f80dba8d
MT
2947 If this is set, fio will compress the I/O logs as it goes, to keep the
2948 memory footprint lower. When a log reaches the specified size, that chunk is
2949 removed and compressed in the background. Given that I/O logs are fairly
2950 highly compressible, this yields a nice memory savings for longer runs. The
2951 downside is that the compression will consume some background CPU cycles, so
2952 it may impact the run. This, however, is also true if the logging ends up
2953 consuming most of the system memory. So pick your poison. The I/O logs are
2954 saved normally at the end of a run, by decompressing the chunks and storing
2955 them in the specified log file. This feature depends on the availability of
2956 zlib.
e0b0d892 2957
f80dba8d 2958.. option:: log_compression_cpus=str
e0b0d892 2959
f80dba8d
MT
2960 Define the set of CPUs that are allowed to handle online log compression for
2961 the I/O jobs. This can provide better isolation between performance
0cf90a62
SW
2962 sensitive jobs, and background compression work. See
2963 :option:`cpus_allowed` for the format used.
9e684a49 2964
f80dba8d 2965.. option:: log_store_compressed=bool
9e684a49 2966
f80dba8d
MT
2967 If set, fio will store the log files in a compressed format. They can be
2968 decompressed with fio, using the :option:`--inflate-log` command line
2969 parameter. The files will be stored with a :file:`.fz` suffix.
9e684a49 2970
f80dba8d 2971.. option:: log_unix_epoch=bool
9e684a49 2972
f80dba8d
MT
2973 If set, fio will log Unix timestamps to the log files produced by enabling
2974 write_type_log for each log type, instead of the default zero-based
2975 timestamps.
2976
2977.. option:: block_error_percentiles=bool
2978
2979 If set, record errors in trim block-sized units from writes and trims and
2980 output a histogram of how many trims it took to get to errors, and what kind
2981 of error was encountered.
2982
2983.. option:: bwavgtime=int
2984
2985 Average the calculated bandwidth over the given time. Value is specified in
2986 milliseconds. If the job also does bandwidth logging through
2987 :option:`write_bw_log`, then the minimum of this option and
2988 :option:`log_avg_msec` will be used. Default: 500ms.
2989
2990.. option:: iopsavgtime=int
2991
2992 Average the calculated IOPS over the given time. Value is specified in
2993 milliseconds. If the job also does IOPS logging through
2994 :option:`write_iops_log`, then the minimum of this option and
2995 :option:`log_avg_msec` will be used. Default: 500ms.
2996
2997.. option:: disk_util=bool
2998
2999 Generate disk utilization statistics, if the platform supports it.
3000 Default: true.
3001
3002.. option:: disable_lat=bool
3003
3004 Disable measurements of total latency numbers. Useful only for cutting back
3005 the number of calls to :manpage:`gettimeofday(2)`, as that does impact
3006 performance at really high IOPS rates. Note that to really get rid of a
3007 large amount of these calls, this option must be used with
f75ede1d 3008 :option:`disable_slat` and :option:`disable_bw_measurement` as well.
f80dba8d
MT
3009
3010.. option:: disable_clat=bool
3011
3012 Disable measurements of completion latency numbers. See
3013 :option:`disable_lat`.
3014
3015.. option:: disable_slat=bool
3016
3017 Disable measurements of submission latency numbers. See
f50fbdda 3018 :option:`disable_lat`.
f80dba8d 3019
f75ede1d 3020.. option:: disable_bw_measurement=bool, disable_bw=bool
f80dba8d
MT
3021
3022 Disable measurements of throughput/bandwidth numbers. See
3023 :option:`disable_lat`.
3024
3025.. option:: clat_percentiles=bool
3026
b599759b
JA
3027 Enable the reporting of percentiles of completion latencies. This
3028 option is mutually exclusive with :option:`lat_percentiles`.
3029
3030.. option:: lat_percentiles=bool
3031
b71968b1 3032 Enable the reporting of percentiles of I/O latencies. This is similar
b599759b
JA
3033 to :option:`clat_percentiles`, except that this includes the
3034 submission latency. This option is mutually exclusive with
3035 :option:`clat_percentiles`.
f80dba8d
MT
3036
3037.. option:: percentile_list=float_list
3038
c32ba107
JA
3039 Overwrite the default list of percentiles for completion latencies and
3040 the block error histogram. Each number is a floating number in the
3041 range (0,100], and the maximum length of the list is 20. Use ``:`` to
3042 separate the numbers, and list the numbers in ascending order. For
3043 example, ``--percentile_list=99.5:99.9`` will cause fio to report the
3044 values of completion latency below which 99.5% and 99.9% of the observed
3045 latencies fell, respectively.
f80dba8d 3046
e883cb35
JF
3047.. option:: significant_figures=int
3048
c32ba107
JA
3049 If using :option:`--output-format` of `normal`, set the significant
3050 figures to this value. Higher values will yield more precise IOPS and
3051 throughput units, while lower values will round. Requires a minimum
3052 value of 1 and a maximum value of 10. Defaults to 4.
e883cb35 3053
f80dba8d
MT
3054
3055Error handling
3056~~~~~~~~~~~~~~
3057
3058.. option:: exitall_on_error
3059
3060 When one job finishes in error, terminate the rest. The default is to wait
3061 for each job to finish.
3062
3063.. option:: continue_on_error=str
3064
3065 Normally fio will exit the job on the first observed failure. If this option
3066 is set, fio will continue the job when there is a 'non-fatal error' (EIO or
3067 EILSEQ) until the runtime is exceeded or the I/O size specified is
3068 completed. If this option is used, there are two more stats that are
3069 appended, the total error count and the first error. The error field given
3070 in the stats is the first error that was hit during the run.
3071
3072 The allowed values are:
3073
3074 **none**
3075 Exit on any I/O or verify errors.
3076
3077 **read**
3078 Continue on read errors, exit on all others.
3079
3080 **write**
3081 Continue on write errors, exit on all others.
3082
3083 **io**
3084 Continue on any I/O error, exit on all others.
3085
3086 **verify**
3087 Continue on verify errors, exit on all others.
3088
3089 **all**
3090 Continue on all errors.
3091
3092 **0**
3093 Backward-compatible alias for 'none'.
3094
3095 **1**
3096 Backward-compatible alias for 'all'.
3097
3098.. option:: ignore_error=str
3099
3100 Sometimes you want to ignore some errors during test in that case you can
a35ef7cb
TK
3101 specify error list for each error type, instead of only being able to
3102 ignore the default 'non-fatal error' using :option:`continue_on_error`.
f80dba8d
MT
3103 ``ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST`` errors for
3104 given error type is separated with ':'. Error may be symbol ('ENOSPC',
3105 'ENOMEM') or integer. Example::
3106
3107 ignore_error=EAGAIN,ENOSPC:122
3108
3109 This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from
a35ef7cb
TK
3110 WRITE. This option works by overriding :option:`continue_on_error` with
3111 the list of errors for each error type if any.
f80dba8d
MT
3112
3113.. option:: error_dump=bool
3114
3115 If set dump every error even if it is non fatal, true by default. If
3116 disabled only fatal error will be dumped.
3117
f75ede1d
SW
3118Running predefined workloads
3119----------------------------
3120
3121Fio includes predefined profiles that mimic the I/O workloads generated by
3122other tools.
3123
3124.. option:: profile=str
3125
3126 The predefined workload to run. Current profiles are:
3127
3128 **tiobench**
3129 Threaded I/O bench (tiotest/tiobench) like workload.
3130
3131 **act**
3132 Aerospike Certification Tool (ACT) like workload.
3133
3134To view a profile's additional options use :option:`--cmdhelp` after specifying
3135the profile. For example::
3136
f50fbdda 3137 $ fio --profile=act --cmdhelp
f75ede1d
SW
3138
3139Act profile options
3140~~~~~~~~~~~~~~~~~~~
3141
3142.. option:: device-names=str
3143 :noindex:
3144
3145 Devices to use.
3146
3147.. option:: load=int
3148 :noindex:
3149
3150 ACT load multiplier. Default: 1.
3151
3152.. option:: test-duration=time
3153 :noindex:
3154
947e0fe0
SW
3155 How long the entire test takes to run. When the unit is omitted, the value
3156 is given in seconds. Default: 24h.
f75ede1d
SW
3157
3158.. option:: threads-per-queue=int
3159 :noindex:
3160
f50fbdda 3161 Number of read I/O threads per device. Default: 8.
f75ede1d
SW
3162
3163.. option:: read-req-num-512-blocks=int
3164 :noindex:
3165
3166 Number of 512B blocks to read at the time. Default: 3.
3167
3168.. option:: large-block-op-kbytes=int
3169 :noindex:
3170
3171 Size of large block ops in KiB (writes). Default: 131072.
3172
3173.. option:: prep
3174 :noindex:
3175
3176 Set to run ACT prep phase.
3177
3178Tiobench profile options
3179~~~~~~~~~~~~~~~~~~~~~~~~
3180
3181.. option:: size=str
3182 :noindex:
3183
f50fbdda 3184 Size in MiB.
f75ede1d
SW
3185
3186.. option:: block=int
3187 :noindex:
3188
3189 Block size in bytes. Default: 4096.
3190
3191.. option:: numruns=int
3192 :noindex:
3193
3194 Number of runs.
3195
3196.. option:: dir=str
3197 :noindex:
3198
3199 Test directory.
3200
3201.. option:: threads=int
3202 :noindex:
3203
3204 Number of threads.
f80dba8d
MT
3205
3206Interpreting the output
3207-----------------------
3208
36214730
SW
3209..
3210 Example output was based on the following:
3211 TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --time_based \
3212 --rate=1256k --bs=14K --name=quick --runtime=1s --name=mixed \
3213 --runtime=2m --rw=rw
3214
f80dba8d
MT
3215Fio spits out a lot of output. While running, fio will display the status of the
3216jobs created. An example of that would be::
3217
9d25d068 3218 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 3219
36214730
SW
3220The characters inside the first set of square brackets denote the current status of
3221each thread. The first character is the first job defined in the job file, and so
3222forth. The possible values (in typical life cycle order) are:
f80dba8d
MT
3223
3224+------+-----+-----------------------------------------------------------+
3225| Idle | Run | |
3226+======+=====+===========================================================+
3227| P | | Thread setup, but not started. |
3228+------+-----+-----------------------------------------------------------+
3229| C | | Thread created. |
3230+------+-----+-----------------------------------------------------------+
3231| I | | Thread initialized, waiting or generating necessary data. |
3232+------+-----+-----------------------------------------------------------+
3233| | p | Thread running pre-reading file(s). |
3234+------+-----+-----------------------------------------------------------+
36214730
SW
3235| | / | Thread is in ramp period. |
3236+------+-----+-----------------------------------------------------------+
f80dba8d
MT
3237| | R | Running, doing sequential reads. |
3238+------+-----+-----------------------------------------------------------+
3239| | r | Running, doing random reads. |
3240+------+-----+-----------------------------------------------------------+
3241| | W | Running, doing sequential writes. |
3242+------+-----+-----------------------------------------------------------+
3243| | w | Running, doing random writes. |
3244+------+-----+-----------------------------------------------------------+
3245| | M | Running, doing mixed sequential reads/writes. |
3246+------+-----+-----------------------------------------------------------+
3247| | m | Running, doing mixed random reads/writes. |
3248+------+-----+-----------------------------------------------------------+
36214730
SW
3249| | D | Running, doing sequential trims. |
3250+------+-----+-----------------------------------------------------------+
3251| | d | Running, doing random trims. |
3252+------+-----+-----------------------------------------------------------+
3253| | F | Running, currently waiting for :manpage:`fsync(2)`. |
f80dba8d
MT
3254+------+-----+-----------------------------------------------------------+
3255| | V | Running, doing verification of written data. |
3256+------+-----+-----------------------------------------------------------+
36214730
SW
3257| f | | Thread finishing. |
3258+------+-----+-----------------------------------------------------------+
f80dba8d
MT
3259| E | | Thread exited, not reaped by main thread yet. |
3260+------+-----+-----------------------------------------------------------+
36214730 3261| _ | | Thread reaped. |
f80dba8d
MT
3262+------+-----+-----------------------------------------------------------+
3263| X | | Thread reaped, exited with an error. |
3264+------+-----+-----------------------------------------------------------+
3265| K | | Thread reaped, exited due to signal. |
3266+------+-----+-----------------------------------------------------------+
3267
36214730
SW
3268..
3269 Example output was based on the following:
3270 TZ=UTC fio --iodepth=8 --ioengine=null --size=100M --runtime=58m \
3271 --time_based --rate=2512k --bs=256K --numjobs=10 \
3272 --name=readers --rw=read --name=writers --rw=write
3273
f80dba8d 3274Fio will condense the thread string as not to take up more space on the command
36214730 3275line than needed. For instance, if you have 10 readers and 10 writers running,
f80dba8d
MT
3276the output would look like this::
3277
9d25d068 3278 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 3279
36214730
SW
3280Note that the status string is displayed in order, so it's possible to tell which of
3281the jobs are currently doing what. In the example above this means that jobs 1--10
3282are readers and 11--20 are writers.
f80dba8d
MT
3283
3284The other values are fairly self explanatory -- number of threads currently
36214730
SW
3285running and doing I/O, the number of currently open files (f=), the estimated
3286completion percentage, the rate of I/O since last check (read speed listed first,
f50fbdda
TK
3287then write speed and optionally trim speed) in terms of bandwidth and IOPS,
3288and time to completion for the current running group. It's impossible to estimate
3289runtime of the following groups (if any).
36214730
SW
3290
3291..
3292 Example output was based on the following:
3293 TZ=UTC fio --iodepth=16 --ioengine=posixaio --filename=/tmp/fiofile \
3294 --direct=1 --size=100M --time_based --runtime=50s --rate_iops=89 \
3295 --bs=7K --name=Client1 --rw=write
3296
3297When fio is done (or interrupted by :kbd:`Ctrl-C`), it will show the data for
3298each thread, group of threads, and disks in that order. For each overall thread (or
3299group) the output looks like::
3300
3301 Client1: (groupid=0, jobs=1): err= 0: pid=16109: Sat Jun 24 12:07:54 2017
3302 write: IOPS=88, BW=623KiB/s (638kB/s)(30.4MiB/50032msec)
3303 slat (nsec): min=500, max=145500, avg=8318.00, stdev=4781.50
3304 clat (usec): min=170, max=78367, avg=4019.02, stdev=8293.31
3305 lat (usec): min=174, max=78375, avg=4027.34, stdev=8291.79
3306 clat percentiles (usec):
3307 | 1.00th=[ 302], 5.00th=[ 326], 10.00th=[ 343], 20.00th=[ 363],
3308 | 30.00th=[ 392], 40.00th=[ 404], 50.00th=[ 416], 60.00th=[ 445],
3309 | 70.00th=[ 816], 80.00th=[ 6718], 90.00th=[12911], 95.00th=[21627],
3310 | 99.00th=[43779], 99.50th=[51643], 99.90th=[68682], 99.95th=[72877],
3311 | 99.99th=[78119]
3312 bw ( KiB/s): min= 532, max= 686, per=0.10%, avg=622.87, stdev=24.82, samples= 100
3313 iops : min= 76, max= 98, avg=88.98, stdev= 3.54, samples= 100
29092211
VF
3314 lat (usec) : 250=0.04%, 500=64.11%, 750=4.81%, 1000=2.79%
3315 lat (msec) : 2=4.16%, 4=1.84%, 10=4.90%, 20=11.33%, 50=5.37%
3316 lat (msec) : 100=0.65%
36214730
SW
3317 cpu : usr=0.27%, sys=0.18%, ctx=12072, majf=0, minf=21
3318 IO depths : 1=85.0%, 2=13.1%, 4=1.8%, 8=0.1%, 16=0.0%, 32=0.0%, >=64=0.0%
3319 submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
3320 complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
3321 issued rwt: total=0,4450,0, short=0,0,0, dropped=0,0,0
3322 latency : target=0, window=0, percentile=100.00%, depth=8
3323
3324The job name (or first job's name when using :option:`group_reporting`) is printed,
3325along with the group id, count of jobs being aggregated, last error id seen (which
3326is 0 when there are no errors), pid/tid of that thread and the time the job/group
3327completed. Below are the I/O statistics for each data direction performed (showing
3328writes in the example above). In the order listed, they denote:
3329
3330**read/write/trim**
3331 The string before the colon shows the I/O direction the statistics
3332 are for. **IOPS** is the average I/Os performed per second. **BW**
3333 is the average bandwidth rate shown as: value in power of 2 format
3334 (value in power of 10 format). The last two values show: (**total
3335 I/O performed** in power of 2 format / **runtime** of that thread).
f80dba8d
MT
3336
3337**slat**
36214730
SW
3338 Submission latency (**min** being the minimum, **max** being the
3339 maximum, **avg** being the average, **stdev** being the standard
3340 deviation). This is the time it took to submit the I/O. For
3341 sync I/O this row is not displayed as the slat is really the
3342 completion latency (since queue/complete is one operation there).
3343 This value can be in nanoseconds, microseconds or milliseconds ---
3344 fio will choose the most appropriate base and print that (in the
3345 example above nanoseconds was the best scale). Note: in :option:`--minimal` mode
0d237712 3346 latencies are always expressed in microseconds.
f80dba8d
MT
3347
3348**clat**
3349 Completion latency. Same names as slat, this denotes the time from
3350 submission to completion of the I/O pieces. For sync I/O, clat will
3351 usually be equal (or very close) to 0, as the time from submit to
3352 complete is basically just CPU time (I/O has already been done, see slat
3353 explanation).
3354
29092211
VF
3355**lat**
3356 Total latency. Same names as slat and clat, this denotes the time from
3357 when fio created the I/O unit to completion of the I/O operation.
3358
f80dba8d 3359**bw**
36214730
SW
3360 Bandwidth statistics based on samples. Same names as the xlat stats,
3361 but also includes the number of samples taken (**samples**) and an
3362 approximate percentage of total aggregate bandwidth this thread
3363 received in its group (**per**). This last value is only really
3364 useful if the threads in this group are on the same disk, since they
3365 are then competing for disk access.
3366
3367**iops**
3368 IOPS statistics based on samples. Same names as bw.
f80dba8d 3369
29092211
VF
3370**lat (nsec/usec/msec)**
3371 The distribution of I/O completion latencies. This is the time from when
3372 I/O leaves fio and when it gets completed. Unlike the separate
3373 read/write/trim sections above, the data here and in the remaining
3374 sections apply to all I/Os for the reporting group. 250=0.04% means that
3375 0.04% of the I/Os completed in under 250us. 500=64.11% means that 64.11%
3376 of the I/Os required 250 to 499us for completion.
3377
f80dba8d
MT
3378**cpu**
3379 CPU usage. User and system time, along with the number of context
3380 switches this thread went through, usage of system and user time, and
3381 finally the number of major and minor page faults. The CPU utilization
3382 numbers are averages for the jobs in that reporting group, while the
23a8e176 3383 context and fault counters are summed.
f80dba8d
MT
3384
3385**IO depths**
a2140525
SW
3386 The distribution of I/O depths over the job lifetime. The numbers are
3387 divided into powers of 2 and each entry covers depths from that value
3388 up to those that are lower than the next entry -- e.g., 16= covers
3389 depths from 16 to 31. Note that the range covered by a depth
3390 distribution entry can be different to the range covered by the
3391 equivalent submit/complete distribution entry.
f80dba8d
MT
3392
3393**IO submit**
3394 How many pieces of I/O were submitting in a single submit call. Each
c60ebc45 3395 entry denotes that amount and below, until the previous entry -- e.g.,
a2140525
SW
3396 16=100% means that we submitted anywhere between 9 to 16 I/Os per submit
3397 call. Note that the range covered by a submit distribution entry can
3398 be different to the range covered by the equivalent depth distribution
3399 entry.
f80dba8d
MT
3400
3401**IO complete**
3402 Like the above submit number, but for completions instead.
3403
36214730
SW
3404**IO issued rwt**
3405 The number of read/write/trim requests issued, and how many of them were
3406 short or dropped.
f80dba8d 3407
29092211 3408**IO latency**
ee21ebee 3409 These values are for :option:`latency_target` and related options. When
29092211
VF
3410 these options are engaged, this section describes the I/O depth required
3411 to meet the specified latency target.
71bfa161 3412
36214730
SW
3413..
3414 Example output was based on the following:
3415 TZ=UTC fio --ioengine=null --iodepth=2 --size=100M --numjobs=2 \
3416 --rate_process=poisson --io_limit=32M --name=read --bs=128k \
3417 --rate=11M --name=write --rw=write --bs=2k --rate=700k
3418
71bfa161 3419After each client has been listed, the group statistics are printed. They
f80dba8d 3420will look like this::
71bfa161 3421
f80dba8d 3422 Run status group 0 (all jobs):
36214730
SW
3423 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
3424 WRITE: bw=1231KiB/s (1261kB/s), 616KiB/s-621KiB/s (630kB/s-636kB/s), io=64.0MiB (67.1MB), run=52747-53223msec
71bfa161 3425
36214730 3426For each data direction it prints:
71bfa161 3427
36214730
SW
3428**bw**
3429 Aggregate bandwidth of threads in this group followed by the
3430 minimum and maximum bandwidth of all the threads in this group.
3431 Values outside of brackets are power-of-2 format and those
3432 within are the equivalent value in a power-of-10 format.
f80dba8d 3433**io**
36214730
SW
3434 Aggregate I/O performed of all threads in this group. The
3435 format is the same as bw.
3436**run**
3437 The smallest and longest runtimes of the threads in this group.
71bfa161 3438
f50fbdda 3439And finally, the disk statistics are printed. This is Linux specific. They will look like this::
71bfa161 3440
f80dba8d
MT
3441 Disk stats (read/write):
3442 sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00%
71bfa161
JA
3443
3444Each value is printed for both reads and writes, with reads first. The
3445numbers denote:
3446
f80dba8d 3447**ios**
c60ebc45 3448 Number of I/Os performed by all groups.
f80dba8d 3449**merge**
007c7be9 3450 Number of merges performed by the I/O scheduler.
f80dba8d
MT
3451**ticks**
3452 Number of ticks we kept the disk busy.
36214730 3453**in_queue**
f80dba8d
MT
3454 Total time spent in the disk queue.
3455**util**
3456 The disk utilization. A value of 100% means we kept the disk
71bfa161
JA
3457 busy constantly, 50% would be a disk idling half of the time.
3458
f80dba8d
MT
3459It is also possible to get fio to dump the current output while it is running,
3460without terminating the job. To do that, send fio the **USR1** signal. You can
3461also get regularly timed dumps by using the :option:`--status-interval`
3462parameter, or by creating a file in :file:`/tmp` named
3463:file:`fio-dump-status`. If fio sees this file, it will unlink it and dump the
3464current output status.
8423bd11 3465
71bfa161 3466
f80dba8d
MT
3467Terse output
3468------------
71bfa161 3469
f80dba8d
MT
3470For scripted usage where you typically want to generate tables or graphs of the
3471results, fio can output the results in a semicolon separated format. The format
3472is one long line of values, such as::
71bfa161 3473
f80dba8d
MT
3474 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%
3475 A description of this job goes here.
562c2d2f
DN
3476
3477The job description (if provided) follows on a second line.
71bfa161 3478
a7f77fa6
SW
3479To enable terse output, use the :option:`--minimal` or
3480:option:`--output-format`\=terse command line options. The
f80dba8d
MT
3481first value is the version of the terse output format. If the output has to be
3482changed for some reason, this number will be incremented by 1 to signify that
3483change.
6820cb3b 3484
a2c95580 3485Split up, the format is as follows (comments in brackets denote when a
007c7be9 3486field was introduced or whether it's specific to some terse version):
71bfa161 3487
f80dba8d
MT
3488 ::
3489
f50fbdda 3490 terse version, fio version [v3], jobname, groupid, error
f80dba8d
MT
3491
3492 READ status::
3493
3494 Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
3495 Submission latency: min, max, mean, stdev (usec)
3496 Completion latency: min, max, mean, stdev (usec)
3497 Completion latency percentiles: 20 fields (see below)
3498 Total latency: min, max, mean, stdev (usec)
f50fbdda
TK
3499 Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
3500 IOPS [v5]: min, max, mean, stdev, number of samples
f80dba8d
MT
3501
3502 WRITE status:
3503
3504 ::
3505
3506 Total IO (KiB), bandwidth (KiB/sec), IOPS, runtime (msec)
3507 Submission latency: min, max, mean, stdev (usec)
247823cc 3508 Completion latency: min, max, mean, stdev (usec)
f80dba8d
MT
3509 Completion latency percentiles: 20 fields (see below)
3510 Total latency: min, max, mean, stdev (usec)
f50fbdda
TK
3511 Bw (KiB/s): min, max, aggregate percentage of total, mean, stdev, number of samples [v5]
3512 IOPS [v5]: min, max, mean, stdev, number of samples
a2c95580
AH
3513
3514 TRIM status [all but version 3]:
3515
f50fbdda 3516 Fields are similar to READ/WRITE status.
f80dba8d
MT
3517
3518 CPU usage::
3519
3520 user, system, context switches, major faults, minor faults
3521
3522 I/O depths::
3523
3524 <=1, 2, 4, 8, 16, 32, >=64
3525
3526 I/O latencies microseconds::
3527
3528 <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
3529
3530 I/O latencies milliseconds::
3531
3532 <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
3533
a2c95580 3534 Disk utilization [v3]::
f80dba8d 3535
f50fbdda
TK
3536 disk name, read ios, write ios, read merges, write merges, read ticks, write ticks,
3537 time spent in queue, disk utilization percentage
f80dba8d
MT
3538
3539 Additional Info (dependent on continue_on_error, default off)::
3540
3541 total # errors, first error code
3542
3543 Additional Info (dependent on description being set)::
3544
3545 Text description
3546
3547Completion latency percentiles can be a grouping of up to 20 sets, so for the
3548terse output fio writes all of them. Each field will look like this::
1db92cb6 3549
f50fbdda 3550 1.00%=6112
1db92cb6 3551
f80dba8d 3552which is the Xth percentile, and the `usec` latency associated with it.
1db92cb6 3553
f50fbdda 3554For `Disk utilization`, all disks used by fio are shown. So for each disk there
f80dba8d 3555will be a disk utilization section.
f2f788dd 3556
2fc26c3d 3557Below is a single line containing short names for each of the fields in the
2831be97 3558minimal output v3, separated by semicolons::
2fc26c3d 3559
f50fbdda 3560 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 3561
25c8b9d7 3562
44c82dba
VF
3563JSON output
3564------------
3565
3566The `json` output format is intended to be both human readable and convenient
3567for automated parsing. For the most part its sections mirror those of the
3568`normal` output. The `runtime` value is reported in msec and the `bw` value is
3569reported in 1024 bytes per second units.
3570
3571
d29c4a91
VF
3572JSON+ output
3573------------
3574
3575The `json+` output format is identical to the `json` output format except that it
3576adds a full dump of the completion latency bins. Each `bins` object contains a
3577set of (key, value) pairs where keys are latency durations and values count how
3578many I/Os had completion latencies of the corresponding duration. For example,
3579consider:
3580
3581 "bins" : { "87552" : 1, "89600" : 1, "94720" : 1, "96768" : 1, "97792" : 1, "99840" : 1, "100864" : 2, "103936" : 6, "104960" : 534, "105984" : 5995, "107008" : 7529, ... }
3582
3583This data indicates that one I/O required 87,552ns to complete, two I/Os required
3584100,864ns to complete, and 7529 I/Os required 107,008ns to complete.
3585
3586Also included with fio is a Python script `fio_jsonplus_clat2csv` that takes
3587json+ output and generates CSV-formatted latency data suitable for plotting.
3588
3589The latency durations actually represent the midpoints of latency intervals.
f50fbdda 3590For details refer to :file:`stat.h`.
d29c4a91
VF
3591
3592
f80dba8d
MT
3593Trace file format
3594-----------------
3595
3596There are two trace file format that you can encounter. The older (v1) format is
3597unsupported since version 1.20-rc3 (March 2008). It will still be described
25c8b9d7
PD
3598below in case that you get an old trace and want to understand it.
3599
3600In any case the trace is a simple text file with a single action per line.
3601
3602
f80dba8d
MT
3603Trace file format v1
3604~~~~~~~~~~~~~~~~~~~~
3605
3606Each line represents a single I/O action in the following format::
3607
3608 rw, offset, length
25c8b9d7 3609
f50fbdda 3610where `rw=0/1` for read/write, and the `offset` and `length` entries being in bytes.
25c8b9d7 3611
22413915 3612This format is not supported in fio versions >= 1.20-rc3.
25c8b9d7 3613
25c8b9d7 3614
f80dba8d
MT
3615Trace file format v2
3616~~~~~~~~~~~~~~~~~~~~
25c8b9d7 3617
f80dba8d
MT
3618The second version of the trace file format was added in fio version 1.17. It
3619allows to access more then one file per trace and has a bigger set of possible
3620file actions.
25c8b9d7 3621
f80dba8d 3622The first line of the trace file has to be::
25c8b9d7 3623
f80dba8d 3624 fio version 2 iolog
25c8b9d7
PD
3625
3626Following this can be lines in two different formats, which are described below.
3627
f80dba8d 3628The file management format::
25c8b9d7 3629
f80dba8d 3630 filename action
25c8b9d7 3631
f50fbdda 3632The `filename` is given as an absolute path. The `action` can be one of these:
25c8b9d7 3633
f80dba8d 3634**add**
f50fbdda 3635 Add the given `filename` to the trace.
f80dba8d 3636**open**
f50fbdda 3637 Open the file with the given `filename`. The `filename` has to have
f80dba8d
MT
3638 been added with the **add** action before.
3639**close**
f50fbdda 3640 Close the file with the given `filename`. The file has to have been
f80dba8d
MT
3641 opened before.
3642
3643
3644The file I/O action format::
3645
3646 filename action offset length
3647
3648The `filename` is given as an absolute path, and has to have been added and
3649opened before it can be used with this format. The `offset` and `length` are
3650given in bytes. The `action` can be one of these:
3651
3652**wait**
3653 Wait for `offset` microseconds. Everything below 100 is discarded.
3654 The time is relative to the previous `wait` statement.
3655**read**
3656 Read `length` bytes beginning from `offset`.
3657**write**
3658 Write `length` bytes beginning from `offset`.
3659**sync**
3660 :manpage:`fsync(2)` the file.
3661**datasync**
3662 :manpage:`fdatasync(2)` the file.
3663**trim**
3664 Trim the given file from the given `offset` for `length` bytes.
3665
3666CPU idleness profiling
3667----------------------
3668
3669In some cases, we want to understand CPU overhead in a test. For example, we
3670test patches for the specific goodness of whether they reduce CPU usage.
3671Fio implements a balloon approach to create a thread per CPU that runs at idle
3672priority, meaning that it only runs when nobody else needs the cpu.
3673By measuring the amount of work completed by the thread, idleness of each CPU
3674can be derived accordingly.
3675
3676An unit work is defined as touching a full page of unsigned characters. Mean and
3677standard deviation of time to complete an unit work is reported in "unit work"
3678section. Options can be chosen to report detailed percpu idleness or overall
3679system idleness by aggregating percpu stats.
3680
3681
3682Verification and triggers
3683-------------------------
3684
3685Fio is usually run in one of two ways, when data verification is done. The first
3686is a normal write job of some sort with verify enabled. When the write phase has
3687completed, fio switches to reads and verifies everything it wrote. The second
3688model is running just the write phase, and then later on running the same job
3689(but with reads instead of writes) to repeat the same I/O patterns and verify
3690the contents. Both of these methods depend on the write phase being completed,
3691as fio otherwise has no idea how much data was written.
3692
3693With verification triggers, fio supports dumping the current write state to
3694local files. Then a subsequent read verify workload can load this state and know
3695exactly where to stop. This is useful for testing cases where power is cut to a
3696server in a managed fashion, for instance.
99b9a85a
JA
3697
3698A verification trigger consists of two things:
3699
f80dba8d
MT
37001) Storing the write state of each job.
37012) Executing a trigger command.
99b9a85a 3702
f80dba8d
MT
3703The write state is relatively small, on the order of hundreds of bytes to single
3704kilobytes. It contains information on the number of completions done, the last X
3705completions, etc.
99b9a85a 3706
f80dba8d
MT
3707A trigger is invoked either through creation ('touch') of a specified file in
3708the system, or through a timeout setting. If fio is run with
9207a0cb 3709:option:`--trigger-file`\= :file:`/tmp/trigger-file`, then it will continually
f80dba8d
MT
3710check for the existence of :file:`/tmp/trigger-file`. When it sees this file, it
3711will fire off the trigger (thus saving state, and executing the trigger
99b9a85a
JA
3712command).
3713
f80dba8d
MT
3714For client/server runs, there's both a local and remote trigger. If fio is
3715running as a server backend, it will send the job states back to the client for
3716safe storage, then execute the remote trigger, if specified. If a local trigger
3717is specified, the server will still send back the write state, but the client
3718will then execute the trigger.
99b9a85a 3719
f80dba8d
MT
3720Verification trigger example
3721~~~~~~~~~~~~~~~~~~~~~~~~~~~~
99b9a85a 3722
f50fbdda
TK
3723Let's say we want to run a powercut test on the remote Linux machine 'server'.
3724Our write workload is in :file:`write-test.fio`. We want to cut power to 'server' at
f80dba8d
MT
3725some point during the run, and we'll run this test from the safety or our local
3726machine, 'localbox'. On the server, we'll start the fio backend normally::
99b9a85a 3727
f80dba8d 3728 server# fio --server
99b9a85a 3729
f80dba8d 3730and on the client, we'll fire off the workload::
99b9a85a 3731
f80dba8d 3732 localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger-remote="bash -c \"echo b > /proc/sysrq-triger\""
99b9a85a 3733
f80dba8d 3734We set :file:`/tmp/my-trigger` as the trigger file, and we tell fio to execute::
99b9a85a 3735
f80dba8d 3736 echo b > /proc/sysrq-trigger
99b9a85a 3737
f80dba8d
MT
3738on the server once it has received the trigger and sent us the write state. This
3739will work, but it's not **really** cutting power to the server, it's merely
3740abruptly rebooting it. If we have a remote way of cutting power to the server
3741through IPMI or similar, we could do that through a local trigger command
4502cb42 3742instead. Let's assume we have a script that does IPMI reboot of a given hostname,
f80dba8d
MT
3743ipmi-reboot. On localbox, we could then have run fio with a local trigger
3744instead::
99b9a85a 3745
f80dba8d 3746 localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger="ipmi-reboot server"
99b9a85a 3747
f80dba8d
MT
3748For this case, fio would wait for the server to send us the write state, then
3749execute ``ipmi-reboot server`` when that happened.
3750
3751Loading verify state
3752~~~~~~~~~~~~~~~~~~~~
3753
4502cb42 3754To load stored write state, a read verification job file must contain the
f80dba8d 3755:option:`verify_state_load` option. If that is set, fio will load the previously
99b9a85a 3756stored state. For a local fio run this is done by loading the files directly,
f80dba8d
MT
3757and on a client/server run, the server backend will ask the client to send the
3758files over and load them from there.
a3ae5b05
JA
3759
3760
f80dba8d
MT
3761Log File Formats
3762----------------
a3ae5b05
JA
3763
3764Fio supports a variety of log file formats, for logging latencies, bandwidth,
3765and IOPS. The logs share a common format, which looks like this:
3766
5a83478f
SW
3767 *time* (`msec`), *value*, *data direction*, *block size* (`bytes`),
3768 *offset* (`bytes`)
a3ae5b05 3769
5a83478f 3770*Time* for the log entry is always in milliseconds. The *value* logged depends
a3ae5b05
JA
3771on the type of log, it will be one of the following:
3772
f80dba8d 3773 **Latency log**
168bb587 3774 Value is latency in nsecs
f80dba8d
MT
3775 **Bandwidth log**
3776 Value is in KiB/sec
3777 **IOPS log**
3778 Value is IOPS
3779
3780*Data direction* is one of the following: