1 .TH fio 1 "September 2007" "User Manual"
3 fio \- flexible I/O tester
6 [\fIoptions\fR] [\fIjobfile\fR]...
9 is a tool that will spawn a number of threads or processes doing a
10 particular type of I/O action as specified by the user.
11 The typical use of fio is to write a job file matching the I/O load
12 one wants to simulate.
15 .BI \-\-output \fR=\fPfilename
16 Write output to \fIfilename\fR.
18 .BI \-\-timeout \fR=\fPtimeout
19 Limit run time to \fItimeout\fR seconds.
22 Generate per-job latency logs.
25 Generate per-job bandwidth logs.
28 Print statistics in a terse, semicolon-delimited format.
30 .BI \-\-showcmd \fR=\fPjobfile
31 Convert \fIjobfile\fR to a set of command-line options.
34 Enable read-only safety checks.
36 .BI \-\-eta \fR=\fPwhen
37 Specifies when real-time ETA estimate should be printed. \fIwhen\fR may
38 be one of `always', `never' or `auto'.
40 .BI \-\-section \fR=\fPsec
41 Only run section \fIsec\fR from job file.
43 .BI \-\-cmdhelp \fR=\fPcommand
44 Print help information for \fIcommand\fR. May be `all' for all commands.
46 .BI \-\-debug \fR=\fPtype
47 Enable verbose tracing of various fio actions. May be `all' for all types
48 or individual types separated by a comma (eg \-\-debug=io,file). `help' will
49 list all available tracing options.
52 Display usage information and exit.
55 Display version information and exit.
57 Job files are in `ini' format. They consist of one or more
58 job definitions, which begin with a job name in square brackets and
59 extend to the next job name. The job name can be any ASCII string
60 except `global', which has a special meaning. Following the job name is
61 a sequence of zero or more parameters, one per line, that define the
62 behavior of the job. Any line starting with a `;' or `#' character is
63 considered a comment and ignored.
65 If \fIjobfile\fR is specified as `-', the job file will be read from
68 The global section contains default parameters for jobs specified in the
69 job file. A job is only affected by global sections residing above it,
70 and there may be any number of global sections. Specific job definitions
71 may override any parameter set in global sections.
74 Some parameters may take arguments of a specific type. The types used are:
77 String: a sequence of alphanumeric characters.
80 SI integer: a whole number, possibly containing a suffix denoting the base unit
81 of the value. Accepted suffixes are `k', 'M', 'G', 'T', and 'P', denoting
82 kilo (1024), mega (1024^2), giga (1024^3), tera (1024^4), and peta (1024^5)
83 respectively. The suffix is not case sensitive. If prefixed with '0x', the
84 value is assumed to be base 16 (hexadecimal). A suffix may include a trailing 'b',
85 for instance 'kb' is identical to 'k'. You can specify a base 10 value
86 by using 'KiB', 'MiB', 'GiB', etc. This is useful for disk drives where
87 values are often given in base 10 values. Specifying '30GiB' will get you
91 Boolean: a true or false value. `0' denotes false, `1' denotes true.
94 Integer range: a range of integers specified in the format
95 \fIlower\fR:\fIupper\fR or \fIlower\fR\-\fIupper\fR. \fIlower\fR and
96 \fIupper\fR may contain a suffix as described above. If an option allows two
97 sets of ranges, they are separated with a `,' or `/' character. For example:
101 List of floating numbers: A list of floating numbers, separated by
106 May be used to override the job name. On the command line, this parameter
107 has the special purpose of signalling the start of a new job.
109 .BI description \fR=\fPstr
110 Human-readable description of the job. It is printed when the job is run, but
111 otherwise has no special purpose.
113 .BI directory \fR=\fPstr
114 Prefix filenames with this directory. Used to place files in a location other
117 .BI filename \fR=\fPstr
119 normally makes up a file name based on the job name, thread number, and file
120 number. If you want to share files between threads in a job or several jobs,
121 specify a \fIfilename\fR for each of them to override the default. If the I/O
122 engine used is `net', \fIfilename\fR is the host and port to connect to in the
123 format \fIhost\fR/\fIport\fR. If the I/O engine is file-based, you can specify
124 a number of files by separating the names with a `:' character. `\-' is a
125 reserved name, meaning stdin or stdout, depending on the read/write direction
128 .BI lockfile \fR=\fPstr
129 Fio defaults to not locking any files before it does IO to them. If a file or
130 file descriptor is shared, fio can serialize IO to that file to make the end
131 result consistent. This is usual for emulating real workloads that share files.
137 No locking. This is the default.
140 Only one thread or process may do IO at the time, excluding all others.
143 Read-write locking on the file. Many readers may access the file at the same
144 time, but writes get exclusive access.
147 The option may be post-fixed with a lock batch number. If set, then each
148 thread/process may do that amount of IOs to the file before giving up the lock.
149 Since lock acquisition is expensive, batching the lock/unlocks will speed up IO.
152 .BI opendir \fR=\fPstr
153 Recursively open any files below directory \fIstr\fR.
155 .BI readwrite \fR=\fPstr "\fR,\fP rw" \fR=\fPstr
156 Type of I/O pattern. Accepted values are:
173 Mixed sequential reads and writes.
176 Mixed random reads and writes.
179 For mixed I/O, the default split is 50/50. For certain types of io the result
180 may still be skewed a bit, since the speed may be different. It is possible to
181 specify a number of IO's to do before getting a new offset, this is one by
182 appending a `:\fI<nr>\fR to the end of the string given. For a random read, it
183 would look like \fBrw=randread:8\fR for passing in an offset modifier with a
184 value of 8. If the postfix is used with a sequential IO pattern, then the value
185 specified will be added to the generated offset for each IO. For instance,
186 using \fBrw=write:4k\fR will skip 4k for every write. It turns sequential IO
187 into sequential IO with holes. See the \fBrw_sequencer\fR option.
190 .BI rw_sequencer \fR=\fPstr
191 If an offset modifier is given by appending a number to the \fBrw=<str>\fR line,
192 then this option controls how that number modifies the IO offset being
193 generated. Accepted values are:
198 Generate sequential offset
201 Generate the same offset
204 \fBsequential\fR is only useful for random IO, where fio would normally
205 generate a new random offset for every IO. If you append eg 8 to randread, you
206 would get a new random offset for every 8 IO's. The result would be a seek for
207 only every 8 IO's, instead of for every IO. Use \fBrw=randread:8\fR to specify
208 that. As sequential IO is already sequential, setting \fBsequential\fR for that
209 would not result in any differences. \fBidentical\fR behaves in a similar
210 fashion, except it sends the same offset 8 number of times before generating a
215 .BI kb_base \fR=\fPint
216 The base unit for a kilobyte. The defacto base is 2^10, 1024. Storage
217 manufacturers like to use 10^3 or 1000 as a base ten unit instead, for obvious
218 reasons. Allow values are 1024 or 1000, with 1024 being the default.
220 .BI randrepeat \fR=\fPbool
221 Seed the random number generator in a predictable way so results are repeatable
222 across runs. Default: true.
224 .BI use_os_rand \fR=\fPbool
225 Fio can either use the random generator supplied by the OS to generator random
226 offsets, or it can use it's own internal generator (based on Tausworthe).
227 Default is to use the internal generator, which is often of better quality and
228 faster. Default: false.
230 .BI fallocate \fR=\fPstr
231 Whether pre-allocation is performed when laying down files. Accepted values
237 Do not pre-allocate space.
240 Pre-allocate via posix_fallocate().
243 Pre-allocate via fallocate() with FALLOC_FL_KEEP_SIZE set.
246 Backward-compatible alias for 'none'.
249 Backward-compatible alias for 'posix'.
252 May not be available on all supported platforms. 'keep' is only
253 available on Linux. If using ZFS on Solaris this must be set to 'none'
254 because ZFS doesn't support it. Default: 'posix'.
257 .BI fadvise_hint \fR=\fPbool
258 Disable use of \fIposix_fadvise\fR\|(2) to advise the kernel what I/O patterns
259 are likely to be issued. Default: true.
262 Total size of I/O for this job. \fBfio\fR will run until this many bytes have
263 been transfered, unless limited by other options (\fBruntime\fR, for instance).
264 Unless \fBnrfiles\fR and \fBfilesize\fR options are given, this amount will be
265 divided between the available files for the job. If not set, fio will use the
266 full size of the given files or devices. If the the files do not exist, size
267 must be given. It is also possible to give size as a percentage between 1 and
268 100. If size=20% is given, fio will use 20% of the full size of the given files
271 .BI fill_device \fR=\fPbool "\fR,\fB fill_fs" \fR=\fPbool
272 Sets size to something really large and waits for ENOSPC (no space left on
273 device) as the terminating condition. Only makes sense with sequential write.
274 For a read workload, the mount point will be filled first then IO started on
275 the result. This option doesn't make sense if operating on a raw device node,
276 since the size of that is already known by the file system. Additionally,
277 writing beyond end-of-device will not return ENOSPC there.
279 .BI filesize \fR=\fPirange
280 Individual file sizes. May be a range, in which case \fBfio\fR will select sizes
281 for files at random within the given range, limited to \fBsize\fR in total (if
282 that is given). If \fBfilesize\fR is not specified, each created file is the
285 .BI blocksize \fR=\fPint[,int] "\fR,\fB bs" \fR=\fPint[,int]
286 Block size for I/O units. Default: 4k. Values for reads and writes can be
287 specified separately in the format \fIread\fR,\fIwrite\fR, either of
288 which may be empty to leave that value at its default.
290 .BI blocksize_range \fR=\fPirange[,irange] "\fR,\fB bsrange" \fR=\fPirange[,irange]
291 Specify a range of I/O block sizes. The issued I/O unit will always be a
292 multiple of the minimum size, unless \fBblocksize_unaligned\fR is set. Applies
293 to both reads and writes if only one range is given, but can be specified
294 separately with a comma seperating the values. Example: bsrange=1k-4k,2k-8k.
295 Also (see \fBblocksize\fR).
297 .BI bssplit \fR=\fPstr
298 This option allows even finer grained control of the block sizes issued,
299 not just even splits between them. With this option, you can weight various
300 block sizes for exact control of the issued IO for a job that has mixed
301 block sizes. The format of the option is bssplit=blocksize/percentage,
302 optionally adding as many definitions as needed separated by a colon.
303 Example: bssplit=4k/10:64k/50:32k/40 would issue 50% 64k blocks, 10% 4k
304 blocks and 40% 32k blocks. \fBbssplit\fR also supports giving separate
305 splits to reads and writes. The format is identical to what the
306 \fBbs\fR option accepts, the read and write parts are separated with a
309 .B blocksize_unaligned\fR,\fP bs_unaligned
310 If set, any size in \fBblocksize_range\fR may be used. This typically won't
311 work with direct I/O, as that normally requires sector alignment.
313 .BI blockalign \fR=\fPint[,int] "\fR,\fB ba" \fR=\fPint[,int]
314 At what boundary to align random IO offsets. Defaults to the same as 'blocksize'
315 the minimum blocksize given. Minimum alignment is typically 512b
316 for using direct IO, though it usually depends on the hardware block size.
317 This option is mutually exclusive with using a random map for files, so it
318 will turn off that option.
321 Initialise buffers with all zeros. Default: fill buffers with random data.
324 If this option is given, fio will refill the IO buffers on every submit. The
325 default is to only fill it at init time and reuse that data. Only makes sense
326 if zero_buffers isn't specified, naturally. If data verification is enabled,
327 refill_buffers is also automatically enabled.
329 .BI nrfiles \fR=\fPint
330 Number of files to use for this job. Default: 1.
332 .BI openfiles \fR=\fPint
333 Number of files to keep open at the same time. Default: \fBnrfiles\fR.
335 .BI file_service_type \fR=\fPstr
336 Defines how files to service are selected. The following types are defined:
341 Choose a file at random
344 Round robin over open files (default).
346 Do each file in the set sequentially.
349 The number of I/Os to issue before switching a new file can be specified by
350 appending `:\fIint\fR' to the service type.
353 .BI ioengine \fR=\fPstr
354 Defines how the job issues I/O. The following types are defined:
359 Basic \fIread\fR\|(2) or \fIwrite\fR\|(2) I/O. \fIfseek\fR\|(2) is used to
360 position the I/O location.
363 Basic \fIpread\fR\|(2) or \fIpwrite\fR\|(2) I/O.
366 Basic \fIreadv\fR\|(2) or \fIwritev\fR\|(2) I/O. Will emulate queuing by
367 coalescing adjacents IOs into a single submission.
370 Linux native asynchronous I/O. This engine also has a sub-option,
371 \fBuserspace_reap\fR. To set it, use \fBioengine=libaio:userspace_reap\fR.
372 Normally, with the libaio engine in use, fio will use the
373 \fIio_getevents\fR\|(3) system call to reap newly returned events. With this
374 flag turned on, the AIO ring will be read directly from user-space to reap
375 events. The reaping mode is only enabled when polling for a minimum of \fB0\fR
376 events (eg when \fBiodepth_batch_complete=0\fR).
379 POSIX asynchronous I/O using \fIaio_read\fR\|(3) and \fIaio_write\fR\|(3).
382 Solaris native asynchronous I/O.
385 Windows native asynchronous I/O.
388 File is memory mapped with \fImmap\fR\|(2) and data copied using
392 \fIsplice\fR\|(2) is used to transfer the data and \fIvmsplice\fR\|(2) to
393 transfer data from user-space to the kernel.
396 Use the syslet system calls to make regular read/write asynchronous.
399 SCSI generic sg v3 I/O. May be either synchronous using the SG_IO ioctl, or if
400 the target is an sg character device, we use \fIread\fR\|(2) and
401 \fIwrite\fR\|(2) for asynchronous I/O.
404 Doesn't transfer any data, just pretends to. Mainly used to exercise \fBfio\fR
405 itself and for debugging and testing purposes.
408 Transfer over the network. \fBfilename\fR must be set appropriately to
409 `\fIhost\fR/\fIport\fR' regardless of data direction. If receiving, only the
410 \fIport\fR argument is used.
413 Like \fBnet\fR, but uses \fIsplice\fR\|(2) and \fIvmsplice\fR\|(2) to map data
417 Doesn't transfer any data, but burns CPU cycles according to \fBcpuload\fR and
418 \fBcpucycles\fR parameters.
421 The GUASI I/O engine is the Generic Userspace Asynchronous Syscall Interface
422 approach to asycnronous I/O.
424 See <http://www.xmailserver.org/guasi\-lib.html>.
427 The RDMA I/O engine supports both RDMA memory semantics (RDMA_WRITE/RDMA_READ)
428 and channel semantics (Send/Recv) for the InfiniBand, RoCE and iWARP protocols.
431 Loads an external I/O engine object file. Append the engine filename as
436 .BI iodepth \fR=\fPint
437 Number of I/O units to keep in flight against the file. Note that increasing
438 iodepth beyond 1 will not affect synchronous ioengines (except for small
439 degress when verify_async is in use). Even async engines my impose OS
440 restrictions causing the desired depth not to be achieved. This may happen on
441 Linux when using libaio and not setting \fBdirect\fR=1, since buffered IO is
442 not async on that OS. Keep an eye on the IO depth distribution in the
443 fio output to verify that the achieved depth is as expected. Default: 1.
445 .BI iodepth_batch \fR=\fPint
446 Number of I/Os to submit at once. Default: \fBiodepth\fR.
448 .BI iodepth_batch_complete \fR=\fPint
449 This defines how many pieces of IO to retrieve at once. It defaults to 1 which
450 means that we'll ask for a minimum of 1 IO in the retrieval process from the
451 kernel. The IO retrieval will go on until we hit the limit set by
452 \fBiodepth_low\fR. If this variable is set to 0, then fio will always check for
453 completed events before queuing more IO. This helps reduce IO latency, at the
454 cost of more retrieval system calls.
456 .BI iodepth_low \fR=\fPint
457 Low watermark indicating when to start filling the queue again. Default:
460 .BI direct \fR=\fPbool
461 If true, use non-buffered I/O (usually O_DIRECT). Default: false.
463 .BI buffered \fR=\fPbool
464 If true, use buffered I/O. This is the opposite of the \fBdirect\fR parameter.
467 .BI offset \fR=\fPint
468 Offset in the file to start I/O. Data before the offset will not be touched.
471 How many I/Os to perform before issuing an \fBfsync\fR\|(2) of dirty data. If
472 0, don't sync. Default: 0.
474 .BI fdatasync \fR=\fPint
475 Like \fBfsync\fR, but uses \fBfdatasync\fR\|(2) instead to only sync the
476 data parts of the file. Default: 0.
478 .BI sync_file_range \fR=\fPstr:int
479 Use sync_file_range() for every \fRval\fP number of write operations. Fio will
480 track range of writes that have happened since the last sync_file_range() call.
481 \fRstr\fP can currently be one or more of:
485 SYNC_FILE_RANGE_WAIT_BEFORE
488 SYNC_FILE_RANGE_WRITE
491 SYNC_FILE_RANGE_WRITE
495 So if you do sync_file_range=wait_before,write:8, fio would use
496 \fBSYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE\fP for every 8 writes.
497 Also see the sync_file_range(2) man page. This option is Linux specific.
499 .BI overwrite \fR=\fPbool
500 If writing, setup the file first and do overwrites. Default: false.
502 .BI end_fsync \fR=\fPbool
503 Sync file contents when job exits. Default: false.
505 .BI fsync_on_close \fR=\fPbool
506 If true, sync file contents on close. This differs from \fBend_fsync\fR in that
507 it will happen on every close, not just at the end of the job. Default: false.
509 .BI rwmixcycle \fR=\fPint
510 How many milliseconds before switching between reads and writes for a mixed
511 workload. Default: 500ms.
513 .BI rwmixread \fR=\fPint
514 Percentage of a mixed workload that should be reads. Default: 50.
516 .BI rwmixwrite \fR=\fPint
517 Percentage of a mixed workload that should be writes. If \fBrwmixread\fR and
518 \fBrwmixwrite\fR are given and do not sum to 100%, the latter of the two
519 overrides the first. This may interfere with a given rate setting, if fio is
520 asked to limit reads or writes to a certain rate. If that is the case, then
521 the distribution may be skewed. Default: 50.
524 Normally \fBfio\fR will cover every block of the file when doing random I/O. If
525 this parameter is given, a new offset will be chosen without looking at past
526 I/O history. This parameter is mutually exclusive with \fBverify\fR.
528 .BI softrandommap \fR=\fPbool
529 See \fBnorandommap\fR. If fio runs with the random block map enabled and it
530 fails to allocate the map, if this option is set it will continue without a
531 random block map. As coverage will not be as complete as with random maps, this
532 option is disabled by default.
535 Run job with given nice value. See \fInice\fR\|(2).
538 Set I/O priority value of this job between 0 (highest) and 7 (lowest). See
541 .BI prioclass \fR=\fPint
542 Set I/O priority class. See \fIionice\fR\|(1).
544 .BI thinktime \fR=\fPint
545 Stall job for given number of microseconds between issuing I/Os.
547 .BI thinktime_spin \fR=\fPint
548 Pretend to spend CPU time for given number of microseconds, sleeping the rest
549 of the time specified by \fBthinktime\fR. Only valid if \fBthinktime\fR is set.
551 .BI thinktime_blocks \fR=\fPint
552 Number of blocks to issue before waiting \fBthinktime\fR microseconds.
556 Cap bandwidth used by this job. The number is in bytes/sec, the normal postfix
557 rules apply. You can use \fBrate\fR=500k to limit reads and writes to 500k each,
558 or you can specify read and writes separately. Using \fBrate\fR=1m,500k would
559 limit reads to 1MB/sec and writes to 500KB/sec. Capping only reads or writes
560 can be done with \fBrate\fR=,500k or \fBrate\fR=500k,. The former will only
561 limit writes (to 500KB/sec), the latter will only limit reads.
563 .BI ratemin \fR=\fPint
564 Tell \fBfio\fR to do whatever it can to maintain at least the given bandwidth.
565 Failing to meet this requirement will cause the job to exit. The same format
566 as \fBrate\fR is used for read vs write separation.
568 .BI rate_iops \fR=\fPint
569 Cap the bandwidth to this number of IOPS. Basically the same as rate, just
570 specified independently of bandwidth. The same format as \fBrate\fR is used for
571 read vs write seperation. If \fBblocksize\fR is a range, the smallest block
572 size is used as the metric.
574 .BI rate_iops_min \fR=\fPint
575 If this rate of I/O is not met, the job will exit. The same format as \fBrate\fR
576 is used for read vs write seperation.
578 .BI ratecycle \fR=\fPint
579 Average bandwidth for \fBrate\fR and \fBratemin\fR over this number of
580 milliseconds. Default: 1000ms.
582 .BI cpumask \fR=\fPint
583 Set CPU affinity for this job. \fIint\fR is a bitmask of allowed CPUs the job
584 may run on. See \fBsched_setaffinity\fR\|(2).
586 .BI cpus_allowed \fR=\fPstr
587 Same as \fBcpumask\fR, but allows a comma-delimited list of CPU numbers.
589 .BI startdelay \fR=\fPint
590 Delay start of job for the specified number of seconds.
592 .BI runtime \fR=\fPint
593 Terminate processing after the specified number of seconds.
596 If given, run for the specified \fBruntime\fR duration even if the files are
597 completely read or written. The same workload will be repeated as many times
598 as \fBruntime\fR allows.
600 .BI ramp_time \fR=\fPint
601 If set, fio will run the specified workload for this amount of time before
602 logging any performance numbers. Useful for letting performance settle before
603 logging results, thus minimizing the runtime required for stable results. Note
604 that the \fBramp_time\fR is considered lead in time for a job, thus it will
605 increase the total runtime if a special timeout or runtime is specified.
607 .BI invalidate \fR=\fPbool
608 Invalidate buffer-cache for the file prior to starting I/O. Default: true.
611 Use synchronous I/O for buffered writes. For the majority of I/O engines,
612 this means using O_SYNC. Default: false.
614 .BI iomem \fR=\fPstr "\fR,\fP mem" \fR=\fPstr
615 Allocation method for I/O unit buffer. Allowed values are:
620 Allocate memory with \fImalloc\fR\|(3).
623 Use shared memory buffers allocated through \fIshmget\fR\|(2).
626 Same as \fBshm\fR, but use huge pages as backing.
629 Use \fImmap\fR\|(2) for allocation. Uses anonymous memory unless a filename
630 is given after the option in the format `:\fIfile\fR'.
633 Same as \fBmmap\fR, but use huge files as backing.
636 The amount of memory allocated is the maximum allowed \fBblocksize\fR for the
637 job multiplied by \fBiodepth\fR. For \fBshmhuge\fR or \fBmmaphuge\fR to work,
638 the system must have free huge pages allocated. \fBmmaphuge\fR also needs to
639 have hugetlbfs mounted, and \fIfile\fR must point there. At least on Linux,
640 huge pages must be manually allocated. See \fB/proc/sys/vm/nr_hugehages\fR
641 and the documentation for that. Normally you just need to echo an appropriate
642 number, eg echoing 8 will ensure that the OS has 8 huge pages ready for
646 .BI iomem_align \fR=\fPint "\fR,\fP mem_align" \fR=\fPint
647 This indiciates the memory alignment of the IO memory buffers. Note that the
648 given alignment is applied to the first IO unit buffer, if using \fBiodepth\fR
649 the alignment of the following buffers are given by the \fBbs\fR used. In
650 other words, if using a \fBbs\fR that is a multiple of the page sized in the
651 system, all buffers will be aligned to this value. If using a \fBbs\fR that
652 is not page aligned, the alignment of subsequent IO memory buffers is the
653 sum of the \fBiomem_align\fR and \fBbs\fR used.
655 .BI hugepage\-size \fR=\fPint
656 Defines the size of a huge page. Must be at least equal to the system setting.
657 Should be a multiple of 1MB. Default: 4MB.
660 Terminate all jobs when one finishes. Default: wait for each job to finish.
662 .BI bwavgtime \fR=\fPint
663 Average bandwidth calculations over the given time in milliseconds. Default:
666 .BI create_serialize \fR=\fPbool
667 If true, serialize file creation for the jobs. Default: true.
669 .BI create_fsync \fR=\fPbool
670 \fIfsync\fR\|(2) data file after creation. Default: true.
672 .BI create_on_open \fR=\fPbool
673 If true, the files are not created until they are opened for IO by the job.
675 .BI pre_read \fR=\fPbool
676 If this is given, files will be pre-read into memory before starting the given
677 IO operation. This will also clear the \fR \fBinvalidate\fR flag, since it is
678 pointless to pre-read and then drop the cache. This will only work for IO
679 engines that are seekable, since they allow you to read the same data
680 multiple times. Thus it will not work on eg network or splice IO.
682 .BI unlink \fR=\fPbool
683 Unlink job files when done. Default: false.
686 Specifies the number of iterations (runs of the same workload) of this job.
689 .BI do_verify \fR=\fPbool
690 Run the verify phase after a write phase. Only valid if \fBverify\fR is set.
693 .BI verify \fR=\fPstr
694 Method of verifying file contents after each iteration of the job. Allowed
699 .B md5 crc16 crc32 crc32c crc32c-intel crc64 crc7 sha256 sha512 sha1
700 Store appropriate checksum in the header of each block. crc32c-intel is
701 hardware accelerated SSE4.2 driven, falls back to regular crc32c if
702 not supported by the system.
705 Write extra information about each I/O (timestamp, block number, etc.). The
706 block number is verified. See \fBverify_pattern\fR as well.
709 Pretend to verify. Used for testing internals.
712 This option can be used for repeated burn-in tests of a system to make sure
713 that the written data is also correctly read back. If the data direction given
714 is a read or random read, fio will assume that it should verify a previously
715 written file. If the data direction includes any form of write, the verify will
716 be of the newly written data.
719 .BI verify_sort \fR=\fPbool
720 If true, written verify blocks are sorted if \fBfio\fR deems it to be faster to
721 read them back in a sorted manner. Default: true.
723 .BI verify_offset \fR=\fPint
724 Swap the verification header with data somewhere else in the block before
725 writing. It is swapped back before verifying.
727 .BI verify_interval \fR=\fPint
728 Write the verification header for this number of bytes, which should divide
729 \fBblocksize\fR. Default: \fBblocksize\fR.
731 .BI verify_pattern \fR=\fPstr
732 If set, fio will fill the io buffers with this pattern. Fio defaults to filling
733 with totally random bytes, but sometimes it's interesting to fill with a known
734 pattern for io verification purposes. Depending on the width of the pattern,
735 fio will fill 1/2/3/4 bytes of the buffer at the time(it can be either a
736 decimal or a hex number). The verify_pattern if larger than a 32-bit quantity
737 has to be a hex number that starts with either "0x" or "0X". Use with
740 .BI verify_fatal \fR=\fPbool
741 If true, exit the job on the first observed verification failure. Default:
744 .BI verify_dump \fR=\fPbool
745 If set, dump the contents of both the original data block and the data block we
746 read off disk to files. This allows later analysis to inspect just what kind of
747 data corruption occurred. On by default.
749 .BI verify_async \fR=\fPint
750 Fio will normally verify IO inline from the submitting thread. This option
751 takes an integer describing how many async offload threads to create for IO
752 verification instead, causing fio to offload the duty of verifying IO contents
753 to one or more separate threads. If using this offload option, even sync IO
754 engines can benefit from using an \fBiodepth\fR setting higher than 1, as it
755 allows them to have IO in flight while verifies are running.
757 .BI verify_async_cpus \fR=\fPstr
758 Tell fio to set the given CPU affinity on the async IO verification threads.
759 See \fBcpus_allowed\fP for the format used.
761 .BI verify_backlog \fR=\fPint
762 Fio will normally verify the written contents of a job that utilizes verify
763 once that job has completed. In other words, everything is written then
764 everything is read back and verified. You may want to verify continually
765 instead for a variety of reasons. Fio stores the meta data associated with an
766 IO block in memory, so for large verify workloads, quite a bit of memory would
767 be used up holding this meta data. If this option is enabled, fio will write
768 only N blocks before verifying these blocks.
770 .BI verify_backlog_batch \fR=\fPint
771 Control how many blocks fio will verify if verify_backlog is set. If not set,
772 will default to the value of \fBverify_backlog\fR (meaning the entire queue is
773 read back and verified). If \fBverify_backlog_batch\fR is less than
774 \fBverify_backlog\fR then not all blocks will be verified, if
775 \fBverify_backlog_batch\fR is larger than \fBverify_backlog\fR, some blocks
776 will be verified more than once.
778 .B stonewall "\fR,\fP wait_for_previous"
779 Wait for preceding jobs in the job file to exit before starting this one.
780 \fBstonewall\fR implies \fBnew_group\fR.
783 Start a new reporting group. If not given, all jobs in a file will be part
784 of the same reporting group, unless separated by a stonewall.
786 .BI numjobs \fR=\fPint
787 Number of clones (processes/threads performing the same workload) of this job.
791 If set, display per-group reports instead of per-job when \fBnumjobs\fR is
795 Use threads created with \fBpthread_create\fR\|(3) instead of processes created
796 with \fBfork\fR\|(2).
798 .BI zonesize \fR=\fPint
799 Divide file into zones of the specified size in bytes. See \fBzoneskip\fR.
801 .BI zoneskip \fR=\fPint
802 Skip the specified number of bytes when \fBzonesize\fR bytes of data have been
805 .BI write_iolog \fR=\fPstr
806 Write the issued I/O patterns to the specified file. Specify a separate file
807 for each job, otherwise the iologs will be interspersed and the file may be
810 .BI read_iolog \fR=\fPstr
811 Replay the I/O patterns contained in the specified file generated by
812 \fBwrite_iolog\fR, or may be a \fBblktrace\fR binary file.
814 .BI replay_no_stall \fR=\fPint
815 While replaying I/O patterns using \fBread_iolog\fR the default behavior
816 attempts to respect timing information between I/Os. Enabling
817 \fBreplay_no_stall\fR causes I/Os to be replayed as fast as possible while
818 still respecting ordering.
820 .BI replay_redirect \fR=\fPstr
821 While replaying I/O patterns using \fBread_iolog\fR the default behavior
822 is to replay the IOPS onto the major/minor device that each IOP was recorded
823 from. Setting \fBreplay_redirect\fR causes all IOPS to be replayed onto the
824 single specified device regardless of the device it was recorded from.
826 .B write_bw_log \fR=\fPstr
827 If given, write a bandwidth log of the jobs in this job file. Can be used to
828 store data of the bandwidth of the jobs in their lifetime. The included
829 fio_generate_plots script uses gnuplot to turn these text files into nice
830 graphs. See \fBwrite_log_log\fR for behaviour of given filename. For this
831 option, the postfix is _bw.log.
833 .B write_lat_log \fR=\fPstr
834 Same as \fBwrite_bw_log\fR, but writes I/O completion latencies. If no
835 filename is given with this option, the default filename of "jobname_type.log"
836 is used. Even if the filename is given, fio will still append the type of log.
838 .B disable_lat \fR=\fPbool
839 Disable measurements of total latency numbers. Useful only for cutting
840 back the number of calls to gettimeofday, as that does impact performance at
841 really high IOPS rates. Note that to really get rid of a large amount of these
842 calls, this option must be used with disable_slat and disable_bw as well.
844 .B disable_clat \fR=\fPbool
845 Disable measurements of completion latency numbers. See \fBdisable_lat\fR.
847 .B disable_slat \fR=\fPbool
848 Disable measurements of submission latency numbers. See \fBdisable_lat\fR.
850 .B disable_bw_measurement \fR=\fPbool
851 Disable measurements of throughput/bandwidth numbers. See \fBdisable_lat\fR.
853 .BI lockmem \fR=\fPint
854 Pin the specified amount of memory with \fBmlock\fR\|(2). Can be used to
855 simulate a smaller amount of memory.
857 .BI exec_prerun \fR=\fPstr
858 Before running the job, execute the specified command with \fBsystem\fR\|(3).
860 .BI exec_postrun \fR=\fPstr
861 Same as \fBexec_prerun\fR, but the command is executed after the job completes.
863 .BI ioscheduler \fR=\fPstr
864 Attempt to switch the device hosting the file to the specified I/O scheduler.
866 .BI cpuload \fR=\fPint
867 If the job is a CPU cycle-eater, attempt to use the specified percentage of
870 .BI cpuchunks \fR=\fPint
871 If the job is a CPU cycle-eater, split the load into cycles of the
872 given time in milliseconds.
874 .BI disk_util \fR=\fPbool
875 Generate disk utilization statistics if the platform supports it. Default: true.
877 .BI gtod_reduce \fR=\fPbool
878 Enable all of the gettimeofday() reducing options (disable_clat, disable_slat,
879 disable_bw) plus reduce precision of the timeout somewhat to really shrink the
880 gettimeofday() call count. With this option enabled, we only do about 0.4% of
881 the gtod() calls we would have done if all time keeping was enabled.
883 .BI gtod_cpu \fR=\fPint
884 Sometimes it's cheaper to dedicate a single thread of execution to just getting
885 the current time. Fio (and databases, for instance) are very intensive on
886 gettimeofday() calls. With this option, you can set one CPU aside for doing
887 nothing but logging current time to a shared memory location. Then the other
888 threads/processes that run IO workloads need only copy that segment, instead of
889 entering the kernel with a gettimeofday() call. The CPU set aside for doing
890 these time calls will be excluded from other uses. Fio will manually clear it
891 from the CPU mask of other jobs.
893 .BI cgroup \fR=\fPstr
894 Add job to this control group. If it doesn't exist, it will be created.
895 The system must have a mounted cgroup blkio mount point for this to work. If
896 your system doesn't have it mounted, you can do so with:
898 # mount \-t cgroup \-o blkio none /cgroup
900 .BI cgroup_weight \fR=\fPint
901 Set the weight of the cgroup to this value. See the documentation that comes
902 with the kernel, allowed values are in the range of 100..1000.
904 .BI cgroup_nodelete \fR=\fPbool
905 Normally fio will delete the cgroups it has created after the job completion.
906 To override this behavior and to leave cgroups around after the job completion,
907 set cgroup_nodelete=1. This can be useful if one wants to inspect various
908 cgroup files after job completion. Default: false
911 Instead of running as the invoking user, set the user ID to this value before
912 the thread/process does any work.
915 Set group ID, see \fBuid\fR.
917 .BI clat_percentiles \fR=\fPbool
918 Enable the reporting of percentiles of completion latencies.
920 .BI percentile_list \fR=\fPfloat_list
921 Overwrite the default list of percentiles for completion
922 latencies. Each number is a floating number in the range (0,100], and
923 the maximum length of the list is 20. Use ':' to separate the
924 numbers. For example, --percentile_list=99.5:99.9 will cause fio to
925 report the values of completion latency below which 99.5% and 99.9% of
926 the observed latencies fell, respectively.
928 While running, \fBfio\fR will display the status of the created jobs. For
932 Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s]
935 The characters in the first set of brackets denote the current status of each
936 threads. The possible values are:
942 Setup but not started.
948 Initialized, waiting.
951 Running, doing sequential reads.
954 Running, doing random reads.
957 Running, doing sequential writes.
960 Running, doing random writes.
963 Running, doing mixed sequential reads/writes.
966 Running, doing mixed random reads/writes.
969 Running, currently waiting for \fBfsync\fR\|(2).
972 Running, verifying written data.
975 Exited, not reaped by main thread.
978 Exited, thread reaped.
982 The second set of brackets shows the estimated completion percentage of
983 the current group. The third set shows the read and write I/O rate,
984 respectively. Finally, the estimated run time of the job is displayed.
986 When \fBfio\fR completes (or is interrupted by Ctrl-C), it will show data
987 for each thread, each group of threads, and each disk, in that order.
989 Per-thread statistics first show the threads client number, group-id, and
990 error code. The remaining figures are as follows:
994 Number of megabytes of I/O performed.
997 Average data rate (bandwidth).
1003 Submission latency minimum, maximum, average and standard deviation. This is
1004 the time it took to submit the I/O.
1007 Completion latency minimum, maximum, average and standard deviation. This
1008 is the time between submission and completion.
1011 Bandwidth minimum, maximum, percentage of aggregate bandwidth received, average
1012 and standard deviation.
1015 CPU usage statistics. Includes user and system time, number of context switches
1016 this thread went through and number of major and minor page faults.
1019 Distribution of I/O depths. Each depth includes everything less than (or equal)
1020 to it, but greater than the previous depth.
1023 Number of read/write requests issued, and number of short read/write requests.
1026 Distribution of I/O completion latencies. The numbers follow the same pattern
1030 The group statistics show:
1035 Number of megabytes I/O performed.
1038 Aggregate bandwidth of threads in the group.
1041 Minimum average bandwidth a thread saw.
1044 Maximum average bandwidth a thread saw.
1047 Shortest runtime of threads in the group.
1050 Longest runtime of threads in the group.
1054 Finally, disk statistics are printed with reads first:
1059 Number of I/Os performed by all groups.
1062 Number of merges in the I/O scheduler.
1065 Number of ticks we kept the disk busy.
1068 Total time spent in the disk queue.
1075 If the \fB\-\-minimal\fR option is given, the results will be printed in a
1076 semicolon-delimited format suitable for scripted use - a job description
1077 (if provided) follows on a new line. Note that the first
1078 number in the line is the version number. If the output has to be changed
1079 for some reason, this number will be incremented by 1 to signify that
1080 change. The fields are:
1083 .B version, jobname, groupid, error
1087 .B KB I/O, bandwidth \fR(KB/s)\fP, runtime \fR(ms)\fP
1091 .B min, max, mean, standard deviation
1095 .B min, max, mean, standard deviation
1099 .B min, max, mean, standard deviation
1103 .B min, max, aggregate percentage of total, mean, standard deviation
1109 .B KB I/O, bandwidth \fR(KB/s)\fP, runtime \fR(ms)\fP
1113 .B min, max, mean, standard deviation
1117 .B min, max, mean, standard deviation
1121 .B min, max, mean, standard deviation
1125 .B min, max, aggregate percentage of total, mean, standard deviation
1131 .B user, system, context switches, major page faults, minor page faults
1134 IO depth distribution:
1136 .B <=1, 2, 4, 8, 16, 32, >=64
1139 IO latency distribution:
1143 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
1147 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
1151 Error Info (dependent on continue_on_error, default off):
1153 .B total # errors, first error code
1156 .B text description (if provided in config - appears on newline)
1160 was written by Jens Axboe <jens.axboe@oracle.com>,
1161 now Jens Axboe <jaxboe@fusionio.com>.
1163 This man page was written by Aaron Carroll <aaronc@cse.unsw.edu.au> based
1164 on documentation by Jens Axboe.
1165 .SH "REPORTING BUGS"
1166 Report bugs to the \fBfio\fR mailing list <fio@vger.kernel.org>.
1169 For further documentation see \fBHOWTO\fR and \fBREADME\fR.
1171 Sample jobfiles are available in the \fBexamples\fR directory.
projects / fio.git / blob