1 .TH fio 1 "December 2014" "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 \-\-debug \fR=\fPtype
16 Enable verbose tracing of various fio actions. May be `all' for all types
17 or individual types separated by a comma (eg \-\-debug=io,file). `help' will
18 list all available tracing options.
20 .BI \-\-output \fR=\fPfilename
21 Write output to \fIfilename\fR.
23 .BI \-\-runtime \fR=\fPruntime
24 Limit run time to \fIruntime\fR seconds.
27 Generate per-job bandwidth logs.
30 Print statistics in a terse, semicolon-delimited format.
33 Print statistics in selected mode AND terse, semicolon-delimited format.
36 Display version information and exit.
38 .BI \-\-terse\-version \fR=\fPversion
39 Set terse version output format (Current version 3, or older version 2).
42 Display usage information and exit.
45 Perform test and validation of internal CPU clock
47 .BI \-\-crctest[\fR=\fPtest]
48 Test the speed of the builtin checksumming functions. If no argument is given,
49 all of them are tested. Or a comma separated list can be passed, in which
50 case the given ones are tested.
52 .BI \-\-cmdhelp \fR=\fPcommand
53 Print help information for \fIcommand\fR. May be `all' for all commands.
55 .BI \-\-enghelp \fR=\fPioengine[,command]
56 List all commands defined by \fIioengine\fR, or print help for \fIcommand\fR defined by \fIioengine\fR.
58 .BI \-\-showcmd \fR=\fPjobfile
59 Convert \fIjobfile\fR to a set of command-line options.
61 .BI \-\-eta \fR=\fPwhen
62 Specifies when real-time ETA estimate should be printed. \fIwhen\fR may
63 be one of `always', `never' or `auto'.
65 .BI \-\-eta\-newline \fR=\fPtime
66 Force an ETA newline for every `time` period passed.
68 .BI \-\-status\-interval \fR=\fPtime
69 Report full output status every `time` period passed.
72 Turn on safety read-only checks, preventing any attempted write.
74 .BI \-\-section \fR=\fPsec
75 Only run section \fIsec\fR from job file. This option can be used multiple times to add more sections to run.
77 .BI \-\-alloc\-size \fR=\fPkb
78 Set the internal smalloc pool size to \fIkb\fP kilobytes.
80 .BI \-\-warnings\-fatal
81 All fio parser warnings are fatal, causing fio to exit with an error.
83 .BI \-\-max\-jobs \fR=\fPnr
84 Set the maximum allowed number of jobs (threads/processes) to support.
86 .BI \-\-server \fR=\fPargs
87 Start a backend server, with \fIargs\fP specifying what to listen to. See client/server section.
89 .BI \-\-daemonize \fR=\fPpidfile
90 Background a fio server, writing the pid to the given pid file.
92 .BI \-\-client \fR=\fPhost
93 Instead of running the jobs locally, send and run them on the given host.
95 .BI \-\-idle\-prof \fR=\fPoption
96 Report cpu idleness on a system or percpu basis (\fIoption\fP=system,percpu) or run unit work calibration only (\fIoption\fP=calibrate).
98 Job files are in `ini' format. They consist of one or more
99 job definitions, which begin with a job name in square brackets and
100 extend to the next job name. The job name can be any ASCII string
101 except `global', which has a special meaning. Following the job name is
102 a sequence of zero or more parameters, one per line, that define the
103 behavior of the job. Any line starting with a `;' or `#' character is
104 considered a comment and ignored.
106 If \fIjobfile\fR is specified as `-', the job file will be read from
109 The global section contains default parameters for jobs specified in the
110 job file. A job is only affected by global sections residing above it,
111 and there may be any number of global sections. Specific job definitions
112 may override any parameter set in global sections.
115 Some parameters may take arguments of a specific type.
116 Anywhere a numeric value is required, an arithmetic expression may be used,
117 provided it is surrounded by parentheses. Supported operators are:
125 .B multiplication (*)
131 .B exponentiation (^)
135 For time values in expressions, units are microseconds by default. This is
136 different than for time values not in expressions (not enclosed in
137 parentheses). The types used are:
140 String: a sequence of alphanumeric characters.
143 SI integer: a whole number, possibly containing a suffix denoting the base unit
144 of the value. Accepted suffixes are `k', 'M', 'G', 'T', and 'P', denoting
145 kilo (1024), mega (1024^2), giga (1024^3), tera (1024^4), and peta (1024^5)
146 respectively. If prefixed with '0x', the value is assumed to be base 16
147 (hexadecimal). A suffix may include a trailing 'b', for instance 'kb' is
148 identical to 'k'. You can specify a base 10 value by using 'KiB', 'MiB','GiB',
149 etc. This is useful for disk drives where values are often given in base 10
150 values. Specifying '30GiB' will get you 30*1000^3 bytes.
151 When specifying times the default suffix meaning changes, still denoting the
152 base unit of the value, but accepted suffixes are 'D' (days), 'H' (hours), 'M'
153 (minutes), 'S' Seconds, 'ms' (or msec) milli seconds, 'us' (or 'usec') micro
154 seconds. Time values without a unit specify seconds.
155 The suffixes are not case sensitive.
158 Boolean: a true or false value. `0' denotes false, `1' denotes true.
161 Integer range: a range of integers specified in the format
162 \fIlower\fR:\fIupper\fR or \fIlower\fR\-\fIupper\fR. \fIlower\fR and
163 \fIupper\fR may contain a suffix as described above. If an option allows two
164 sets of ranges, they are separated with a `,' or `/' character. For example:
168 List of floating numbers: A list of floating numbers, separated by
173 May be used to override the job name. On the command line, this parameter
174 has the special purpose of signalling the start of a new job.
176 .BI description \fR=\fPstr
177 Human-readable description of the job. It is printed when the job is run, but
178 otherwise has no special purpose.
180 .BI directory \fR=\fPstr
181 Prefix filenames with this directory. Used to place files in a location other
183 You can specify a number of directories by separating the names with a ':'
184 character. These directories will be assigned equally distributed to job clones
185 creates with \fInumjobs\fR as long as they are using generated filenames.
186 If specific \fIfilename(s)\fR are set fio will use the first listed directory,
187 and thereby matching the \fIfilename\fR semantic which generates a file each
188 clone if not specified, but let all clones use the same if set. See
189 \fIfilename\fR for considerations regarding escaping certain characters on
192 .BI filename \fR=\fPstr
194 normally makes up a file name based on the job name, thread number, and file
195 number. If you want to share files between threads in a job or several jobs,
196 specify a \fIfilename\fR for each of them to override the default.
197 If the I/O engine is file-based, you can specify
198 a number of files by separating the names with a `:' character. `\-' is a
199 reserved name, meaning stdin or stdout, depending on the read/write direction
200 set. On Windows, disk devices are accessed as \\.\PhysicalDrive0 for the first
201 device, \\.\PhysicalDrive1 for the second etc. Note: Windows and FreeBSD
202 prevent write access to areas of the disk containing in-use data
203 (e.g. filesystems). If the wanted filename does need to include a colon, then
204 escape that with a '\\' character. For instance, if the filename is
205 "/dev/dsk/foo@3,0:c", then you would use filename="/dev/dsk/foo@3,0\\:c".
207 .BI filename_format \fR=\fPstr
208 If sharing multiple files between jobs, it is usually necessary to have
209 fio generate the exact names that you want. By default, fio will name a file
210 based on the default file format specification of
211 \fBjobname.jobnumber.filenumber\fP. With this option, that can be
212 customized. Fio will recognize and replace the following keywords in this
218 The name of the worker thread or process.
221 The incremental number of the worker thread or process.
224 The incremental number of the file for that worker thread or process.
227 To have dependent jobs share a set of files, this option can be set to
228 have fio generate filenames that are shared between the two. For instance,
229 if \fBtestfiles.$filenum\fR is specified, file number 4 for any job will
230 be named \fBtestfiles.4\fR. The default of \fB$jobname.$jobnum.$filenum\fR
231 will be used if no other format specifier is given.
235 .BI lockfile \fR=\fPstr
236 Fio defaults to not locking any files before it does IO to them. If a file or
237 file descriptor is shared, fio can serialize IO to that file to make the end
238 result consistent. This is usual for emulating real workloads that share files.
244 No locking. This is the default.
247 Only one thread or process may do IO at a time, excluding all others.
250 Read-write locking on the file. Many readers may access the file at the same
251 time, but writes get exclusive access.
255 .BI opendir \fR=\fPstr
256 Recursively open any files below directory \fIstr\fR.
258 .BI readwrite \fR=\fPstr "\fR,\fP rw" \fR=\fPstr
259 Type of I/O pattern. Accepted values are:
270 Sequential trim (Linux block devices only).
279 Random trim (Linux block devices only).
282 Mixed sequential reads and writes.
285 Mixed random reads and writes.
288 For mixed I/O, the default split is 50/50. For certain types of io the result
289 may still be skewed a bit, since the speed may be different. It is possible to
290 specify a number of IO's to do before getting a new offset, this is done by
291 appending a `:\fI<nr>\fR to the end of the string given. For a random read, it
292 would look like \fBrw=randread:8\fR for passing in an offset modifier with a
293 value of 8. If the postfix is used with a sequential IO pattern, then the value
294 specified will be added to the generated offset for each IO. For instance,
295 using \fBrw=write:4k\fR will skip 4k for every write. It turns sequential IO
296 into sequential IO with holes. See the \fBrw_sequencer\fR option.
299 .BI rw_sequencer \fR=\fPstr
300 If an offset modifier is given by appending a number to the \fBrw=<str>\fR line,
301 then this option controls how that number modifies the IO offset being
302 generated. Accepted values are:
307 Generate sequential offset
310 Generate the same offset
313 \fBsequential\fR is only useful for random IO, where fio would normally
314 generate a new random offset for every IO. If you append eg 8 to randread, you
315 would get a new random offset for every 8 IO's. The result would be a seek for
316 only every 8 IO's, instead of for every IO. Use \fBrw=randread:8\fR to specify
317 that. As sequential IO is already sequential, setting \fBsequential\fR for that
318 would not result in any differences. \fBidentical\fR behaves in a similar
319 fashion, except it sends the same offset 8 number of times before generating a
324 .BI kb_base \fR=\fPint
325 The base unit for a kilobyte. The defacto base is 2^10, 1024. Storage
326 manufacturers like to use 10^3 or 1000 as a base ten unit instead, for obvious
327 reasons. Allowed values are 1024 or 1000, with 1024 being the default.
329 .BI unified_rw_reporting \fR=\fPbool
330 Fio normally reports statistics on a per data direction basis, meaning that
331 read, write, and trim are accounted and reported separately. If this option is
332 set fio sums the results and reports them as "mixed" instead.
334 .BI randrepeat \fR=\fPbool
335 Seed the random number generator used for random I/O patterns in a predictable
336 way so the pattern is repeatable across runs. Default: true.
338 .BI allrandrepeat \fR=\fPbool
339 Seed all random number generators in a predictable way so results are
340 repeatable across runs. Default: false.
342 .BI randseed \fR=\fPint
343 Seed the random number generators based on this seed value, to be able to
344 control what sequence of output is being generated. If not set, the random
345 sequence depends on the \fBrandrepeat\fR setting.
347 .BI fallocate \fR=\fPstr
348 Whether pre-allocation is performed when laying down files. Accepted values
354 Do not pre-allocate space.
357 Pre-allocate via \fBposix_fallocate\fR\|(3).
360 Pre-allocate via \fBfallocate\fR\|(2) with FALLOC_FL_KEEP_SIZE set.
363 Backward-compatible alias for 'none'.
366 Backward-compatible alias for 'posix'.
369 May not be available on all supported platforms. 'keep' is only
370 available on Linux. If using ZFS on Solaris this must be set to 'none'
371 because ZFS doesn't support it. Default: 'posix'.
374 .BI fadvise_hint \fR=\fPbool
375 Use \fBposix_fadvise\fR\|(2) to advise the kernel what I/O patterns
376 are likely to be issued. Default: true.
379 Total size of I/O for this job. \fBfio\fR will run until this many bytes have
380 been transferred, unless limited by other options (\fBruntime\fR, for instance,
381 or increased/descreased by \fBio_size\fR). Unless \fBnrfiles\fR and
382 \fBfilesize\fR options are given, this amount will be divided between the
383 available files for the job. If not set, fio will use the full size of the
384 given files or devices. If the files do not exist, size must be given. It is
385 also possible to give size as a percentage between 1 and 100. If size=20% is
386 given, fio will use 20% of the full size of the given files or devices.
388 .BI io_size \fR=\fPint "\fR,\fB io_limit \fR=\fPint
389 Normally fio operates within the region set by \fBsize\fR, which means that
390 the \fBsize\fR option sets both the region and size of IO to be performed.
391 Sometimes that is not what you want. With this option, it is possible to
392 define just the amount of IO that fio should do. For instance, if \fBsize\fR
393 is set to 20G and \fBio_limit\fR is set to 5G, fio will perform IO within
394 the first 20G but exit when 5G have been done. The opposite is also
395 possible - if \fBsize\fR is set to 20G, and \fBio_size\fR is set to 40G, then
396 fio will do 40G of IO within the 0..20G region.
398 .BI fill_device \fR=\fPbool "\fR,\fB fill_fs" \fR=\fPbool
399 Sets size to something really large and waits for ENOSPC (no space left on
400 device) as the terminating condition. Only makes sense with sequential write.
401 For a read workload, the mount point will be filled first then IO started on
402 the result. This option doesn't make sense if operating on a raw device node,
403 since the size of that is already known by the file system. Additionally,
404 writing beyond end-of-device will not return ENOSPC there.
406 .BI filesize \fR=\fPirange
407 Individual file sizes. May be a range, in which case \fBfio\fR will select sizes
408 for files at random within the given range, limited to \fBsize\fR in total (if
409 that is given). If \fBfilesize\fR is not specified, each created file is the
412 .BI file_append \fR=\fPbool
413 Perform IO after the end of the file. Normally fio will operate within the
414 size of a file. If this option is set, then fio will append to the file
415 instead. This has identical behavior to setting \fRoffset\fP to the size
416 of a file. This option is ignored on non-regular files.
418 .BI blocksize \fR=\fPint[,int] "\fR,\fB bs" \fR=\fPint[,int]
419 Block size for I/O units. Default: 4k. Values for reads, writes, and trims
420 can be specified separately in the format \fIread\fR,\fIwrite\fR,\fItrim\fR
421 either of which may be empty to leave that value at its default. If a trailing
422 comma isn't given, the remainder will inherit the last value set.
424 .BI blocksize_range \fR=\fPirange[,irange] "\fR,\fB bsrange" \fR=\fPirange[,irange]
425 Specify a range of I/O block sizes. The issued I/O unit will always be a
426 multiple of the minimum size, unless \fBblocksize_unaligned\fR is set. Applies
427 to both reads and writes if only one range is given, but can be specified
428 separately with a comma separating the values. Example: bsrange=1k-4k,2k-8k.
429 Also (see \fBblocksize\fR).
431 .BI bssplit \fR=\fPstr
432 This option allows even finer grained control of the block sizes issued,
433 not just even splits between them. With this option, you can weight various
434 block sizes for exact control of the issued IO for a job that has mixed
435 block sizes. The format of the option is bssplit=blocksize/percentage,
436 optionally adding as many definitions as needed separated by a colon.
437 Example: bssplit=4k/10:64k/50:32k/40 would issue 50% 64k blocks, 10% 4k
438 blocks and 40% 32k blocks. \fBbssplit\fR also supports giving separate
439 splits to reads and writes. The format is identical to what the
440 \fBbs\fR option accepts, the read and write parts are separated with a
443 .B blocksize_unaligned\fR,\fP bs_unaligned
444 If set, any size in \fBblocksize_range\fR may be used. This typically won't
445 work with direct I/O, as that normally requires sector alignment.
447 .BI blockalign \fR=\fPint[,int] "\fR,\fB ba" \fR=\fPint[,int]
448 At what boundary to align random IO offsets. Defaults to the same as 'blocksize'
449 the minimum blocksize given. Minimum alignment is typically 512b
450 for using direct IO, though it usually depends on the hardware block size.
451 This option is mutually exclusive with using a random map for files, so it
452 will turn off that option.
454 .BI bs_is_seq_rand \fR=\fPbool
455 If this option is set, fio will use the normal read,write blocksize settings as
456 sequential,random instead. Any random read or write will use the WRITE
457 blocksize settings, and any sequential read or write will use the READ
461 Initialize buffers with all zeros. Default: fill buffers with random data.
462 The resulting IO buffers will not be completely zeroed, unless
463 \fPscramble_buffers\fR is also turned off.
466 If this option is given, fio will refill the IO buffers on every submit. The
467 default is to only fill it at init time and reuse that data. Only makes sense
468 if zero_buffers isn't specified, naturally. If data verification is enabled,
469 refill_buffers is also automatically enabled.
471 .BI scramble_buffers \fR=\fPbool
472 If \fBrefill_buffers\fR is too costly and the target is using data
473 deduplication, then setting this option will slightly modify the IO buffer
474 contents to defeat normal de-dupe attempts. This is not enough to defeat
475 more clever block compression attempts, but it will stop naive dedupe
476 of blocks. Default: true.
478 .BI buffer_compress_percentage \fR=\fPint
479 If this is set, then fio will attempt to provide IO buffer content (on WRITEs)
480 that compress to the specified level. Fio does this by providing a mix of
481 random data and a fixed pattern. The fixed pattern is either zeroes, or the
482 pattern specified by \fBbuffer_pattern\fR. If the pattern option is used, it
483 might skew the compression ratio slightly. Note that this is per block size
484 unit, for file/disk wide compression level that matches this setting. Note
485 that this is per block size unit, for file/disk wide compression level that
486 matches this setting, you'll also want to set refill_buffers.
488 .BI buffer_compress_chunk \fR=\fPint
489 See \fBbuffer_compress_percentage\fR. This setting allows fio to manage how
490 big the ranges of random data and zeroed data is. Without this set, fio will
491 provide \fBbuffer_compress_percentage\fR of blocksize random data, followed by
492 the remaining zeroed. With this set to some chunk size smaller than the block
493 size, fio can alternate random and zeroed data throughout the IO buffer.
495 .BI buffer_pattern \fR=\fPstr
496 If set, fio will fill the IO buffers with this pattern. If not set, the contents
497 of IO buffers is defined by the other options related to buffer contents. The
498 setting can be any pattern of bytes, and can be prefixed with 0x for hex
499 values. It may also be a string, where the string must then be wrapped with
502 .BI dedupe_percentage \fR=\fPint
503 If set, fio will generate this percentage of identical buffers when writing.
504 These buffers will be naturally dedupable. The contents of the buffers depend
505 on what other buffer compression settings have been set. It's possible to have
506 the individual buffers either fully compressible, or not at all. This option
507 only controls the distribution of unique buffers.
509 .BI nrfiles \fR=\fPint
510 Number of files to use for this job. Default: 1.
512 .BI openfiles \fR=\fPint
513 Number of files to keep open at the same time. Default: \fBnrfiles\fR.
515 .BI file_service_type \fR=\fPstr
516 Defines how files to service are selected. The following types are defined:
521 Choose a file at random.
524 Round robin over opened files (default).
527 Do each file in the set sequentially.
530 The number of I/Os to issue before switching to a new file can be specified by
531 appending `:\fIint\fR' to the service type.
534 .BI ioengine \fR=\fPstr
535 Defines how the job issues I/O. The following types are defined:
540 Basic \fBread\fR\|(2) or \fBwrite\fR\|(2) I/O. \fBfseek\fR\|(2) is used to
541 position the I/O location.
544 Basic \fBpread\fR\|(2) or \fBpwrite\fR\|(2) I/O.
547 Basic \fBreadv\fR\|(2) or \fBwritev\fR\|(2) I/O. Will emulate queuing by
548 coalescing adjacent IOs into a single submission.
551 Basic \fBpreadv\fR\|(2) or \fBpwritev\fR\|(2) I/O.
554 Linux native asynchronous I/O. This ioengine defines engine specific options.
557 POSIX asynchronous I/O using \fBaio_read\fR\|(3) and \fBaio_write\fR\|(3).
560 Solaris native asynchronous I/O.
563 Windows native asynchronous I/O.
566 File is memory mapped with \fBmmap\fR\|(2) and data copied using
570 \fBsplice\fR\|(2) is used to transfer the data and \fBvmsplice\fR\|(2) to
571 transfer data from user-space to the kernel.
574 Use the syslet system calls to make regular read/write asynchronous.
577 SCSI generic sg v3 I/O. May be either synchronous using the SG_IO ioctl, or if
578 the target is an sg character device, we use \fBread\fR\|(2) and
579 \fBwrite\fR\|(2) for asynchronous I/O.
582 Doesn't transfer any data, just pretends to. Mainly used to exercise \fBfio\fR
583 itself and for debugging and testing purposes.
586 Transfer over the network. The protocol to be used can be defined with the
587 \fBprotocol\fR parameter. Depending on the protocol, \fBfilename\fR,
588 \fBhostname\fR, \fBport\fR, or \fBlisten\fR must be specified.
589 This ioengine defines engine specific options.
592 Like \fBnet\fR, but uses \fBsplice\fR\|(2) and \fBvmsplice\fR\|(2) to map data
593 and send/receive. This ioengine defines engine specific options.
596 Doesn't transfer any data, but burns CPU cycles according to \fBcpuload\fR and
597 \fBcpucycles\fR parameters.
600 The GUASI I/O engine is the Generic Userspace Asynchronous Syscall Interface
601 approach to asynchronous I/O.
603 See <http://www.xmailserver.org/guasi\-lib.html>.
606 The RDMA I/O engine supports both RDMA memory semantics (RDMA_WRITE/RDMA_READ)
607 and channel semantics (Send/Recv) for the InfiniBand, RoCE and iWARP protocols.
610 Loads an external I/O engine object file. Append the engine filename as
614 IO engine that does regular linux native fallocate call to simulate data
615 transfer as fio ioengine
617 DDIR_READ does fallocate(,mode = FALLOC_FL_KEEP_SIZE,)
619 DIR_WRITE does fallocate(,mode = 0)
621 DDIR_TRIM does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE)
624 IO engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate defragment activity
625 request to DDIR_WRITE event
628 IO engine supporting direct access to Ceph Rados Block Devices (RBD) via librbd
629 without the need to use the kernel rbd driver. This ioengine defines engine specific
633 Using Glusterfs libgfapi sync interface to direct access to Glusterfs volumes without
634 having to go through FUSE. This ioengine defines engine specific
638 Using Glusterfs libgfapi async interface to direct access to Glusterfs volumes without
639 having to go through FUSE. This ioengine defines engine specific
643 Read and write through Hadoop (HDFS). The \fBfilename\fR option is used to
644 specify host,port of the hdfs name-node to connect. This engine interprets
645 offsets a little differently. In HDFS, files once created cannot be modified.
646 So random writes are not possible. To imitate this, libhdfs engine expects
647 bunch of small files to be created over HDFS, and engine will randomly pick a
648 file out of those files based on the offset generated by fio backend. (see the
649 example job file to create such files, use rw=write option). Please note, you
650 might want to set necessary environment variables to work with hdfs/libhdfs
656 .BI iodepth \fR=\fPint
657 Number of I/O units to keep in flight against the file. Note that increasing
658 iodepth beyond 1 will not affect synchronous ioengines (except for small
659 degress when verify_async is in use). Even async engines may impose OS
660 restrictions causing the desired depth not to be achieved. This may happen on
661 Linux when using libaio and not setting \fBdirect\fR=1, since buffered IO is
662 not async on that OS. Keep an eye on the IO depth distribution in the
663 fio output to verify that the achieved depth is as expected. Default: 1.
665 .BI iodepth_batch \fR=\fPint
666 Number of I/Os to submit at once. Default: \fBiodepth\fR.
668 .BI iodepth_batch_complete \fR=\fPint
669 This defines how many pieces of IO to retrieve at once. It defaults to 1 which
670 means that we'll ask for a minimum of 1 IO in the retrieval process from the
671 kernel. The IO retrieval will go on until we hit the limit set by
672 \fBiodepth_low\fR. If this variable is set to 0, then fio will always check for
673 completed events before queuing more IO. This helps reduce IO latency, at the
674 cost of more retrieval system calls.
676 .BI iodepth_low \fR=\fPint
677 Low watermark indicating when to start filling the queue again. Default:
680 .BI direct \fR=\fPbool
681 If true, use non-buffered I/O (usually O_DIRECT). Default: false.
683 .BI atomic \fR=\fPbool
684 If value is true, attempt to use atomic direct IO. Atomic writes are guaranteed
685 to be stable once acknowledged by the operating system. Only Linux supports
688 .BI buffered \fR=\fPbool
689 If true, use buffered I/O. This is the opposite of the \fBdirect\fR parameter.
692 .BI offset \fR=\fPint
693 Offset in the file to start I/O. Data before the offset will not be touched.
695 .BI offset_increment \fR=\fPint
696 If this is provided, then the real offset becomes the
697 offset + offset_increment * thread_number, where the thread number is a
698 counter that starts at 0 and is incremented for each sub-job (i.e. when
699 numjobs option is specified). This option is useful if there are several jobs
700 which are intended to operate on a file in parallel disjoint segments, with
701 even spacing between the starting points.
703 .BI number_ios \fR=\fPint
704 Fio will normally perform IOs until it has exhausted the size of the region
705 set by \fBsize\fR, or if it exhaust the allocated time (or hits an error
706 condition). With this setting, the range/size can be set independently of
707 the number of IOs to perform. When fio reaches this number, it will exit
708 normally and report status. Note that this does not extend the amount
709 of IO that will be done, it will only stop fio if this condition is met
710 before other end-of-job criteria.
713 How many I/Os to perform before issuing an \fBfsync\fR\|(2) of dirty data. If
714 0, don't sync. Default: 0.
716 .BI fdatasync \fR=\fPint
717 Like \fBfsync\fR, but uses \fBfdatasync\fR\|(2) instead to only sync the
718 data parts of the file. Default: 0.
720 .BI write_barrier \fR=\fPint
721 Make every Nth write a barrier write.
723 .BI sync_file_range \fR=\fPstr:int
724 Use \fBsync_file_range\fR\|(2) for every \fRval\fP number of write operations. Fio will
725 track range of writes that have happened since the last \fBsync_file_range\fR\|(2) call.
726 \fRstr\fP can currently be one or more of:
730 SYNC_FILE_RANGE_WAIT_BEFORE
733 SYNC_FILE_RANGE_WRITE
736 SYNC_FILE_RANGE_WRITE
740 So if you do sync_file_range=wait_before,write:8, fio would use
741 \fBSYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE\fP for every 8 writes.
742 Also see the \fBsync_file_range\fR\|(2) man page. This option is Linux specific.
744 .BI overwrite \fR=\fPbool
745 If writing, setup the file first and do overwrites. Default: false.
747 .BI end_fsync \fR=\fPbool
748 Sync file contents when a write stage has completed. Default: false.
750 .BI fsync_on_close \fR=\fPbool
751 If true, sync file contents on close. This differs from \fBend_fsync\fR in that
752 it will happen on every close, not just at the end of the job. Default: false.
754 .BI rwmixread \fR=\fPint
755 Percentage of a mixed workload that should be reads. Default: 50.
757 .BI rwmixwrite \fR=\fPint
758 Percentage of a mixed workload that should be writes. If \fBrwmixread\fR and
759 \fBrwmixwrite\fR are given and do not sum to 100%, the latter of the two
760 overrides the first. This may interfere with a given rate setting, if fio is
761 asked to limit reads or writes to a certain rate. If that is the case, then
762 the distribution may be skewed. Default: 50.
764 .BI random_distribution \fR=\fPstr:float
765 By default, fio will use a completely uniform random distribution when asked
766 to perform random IO. Sometimes it is useful to skew the distribution in
767 specific ways, ensuring that some parts of the data is more hot than others.
768 Fio includes the following distribution models:
772 Uniform random distribution
782 When using a zipf or pareto distribution, an input value is also needed to
783 define the access pattern. For zipf, this is the zipf theta. For pareto,
784 it's the pareto power. Fio includes a test program, genzipf, that can be
785 used visualize what the given input values will yield in terms of hit rates.
786 If you wanted to use zipf with a theta of 1.2, you would use
787 random_distribution=zipf:1.2 as the option. If a non-uniform model is used,
788 fio will disable use of the random map.
790 .BI percentage_random \fR=\fPint
791 For a random workload, set how big a percentage should be random. This defaults
792 to 100%, in which case the workload is fully random. It can be set from
793 anywhere from 0 to 100. Setting it to 0 would make the workload fully
794 sequential. It is possible to set different values for reads, writes, and
795 trim. To do so, simply use a comma separated list. See \fBblocksize\fR.
798 Normally \fBfio\fR will cover every block of the file when doing random I/O. If
799 this parameter is given, a new offset will be chosen without looking at past
800 I/O history. This parameter is mutually exclusive with \fBverify\fR.
802 .BI softrandommap \fR=\fPbool
803 See \fBnorandommap\fR. If fio runs with the random block map enabled and it
804 fails to allocate the map, if this option is set it will continue without a
805 random block map. As coverage will not be as complete as with random maps, this
806 option is disabled by default.
808 .BI random_generator \fR=\fPstr
809 Fio supports the following engines for generating IO offsets for random IO:
813 Strong 2^88 cycle random number generator
816 Linear feedback shift register generator
820 Tausworthe is a strong random number generator, but it requires tracking on the
821 side if we want to ensure that blocks are only read or written once. LFSR
822 guarantees that we never generate the same offset twice, and it's also less
823 computationally expensive. It's not a true random generator, however, though
824 for IO purposes it's typically good enough. LFSR only works with single block
825 sizes, not with workloads that use multiple block sizes. If used with such a
826 workload, fio may read or write some blocks multiple times.
829 Run job with given nice value. See \fBnice\fR\|(2).
832 Set I/O priority value of this job between 0 (highest) and 7 (lowest). See
835 .BI prioclass \fR=\fPint
836 Set I/O priority class. See \fBionice\fR\|(1).
838 .BI thinktime \fR=\fPint
839 Stall job for given number of microseconds between issuing I/Os.
841 .BI thinktime_spin \fR=\fPint
842 Pretend to spend CPU time for given number of microseconds, sleeping the rest
843 of the time specified by \fBthinktime\fR. Only valid if \fBthinktime\fR is set.
845 .BI thinktime_blocks \fR=\fPint
846 Only valid if thinktime is set - control how many blocks to issue, before
847 waiting \fBthinktime\fR microseconds. If not set, defaults to 1 which will
848 make fio wait \fBthinktime\fR microseconds after every block. This
849 effectively makes any queue depth setting redundant, since no more than 1 IO
850 will be queued before we have to complete it and do our thinktime. In other
851 words, this setting effectively caps the queue depth if the latter is larger.
855 Cap bandwidth used by this job. The number is in bytes/sec, the normal postfix
856 rules apply. You can use \fBrate\fR=500k to limit reads and writes to 500k each,
857 or you can specify read and writes separately. Using \fBrate\fR=1m,500k would
858 limit reads to 1MB/sec and writes to 500KB/sec. Capping only reads or writes
859 can be done with \fBrate\fR=,500k or \fBrate\fR=500k,. The former will only
860 limit writes (to 500KB/sec), the latter will only limit reads.
862 .BI ratemin \fR=\fPint
863 Tell \fBfio\fR to do whatever it can to maintain at least the given bandwidth.
864 Failing to meet this requirement will cause the job to exit. The same format
865 as \fBrate\fR is used for read vs write separation.
867 .BI rate_iops \fR=\fPint
868 Cap the bandwidth to this number of IOPS. Basically the same as rate, just
869 specified independently of bandwidth. The same format as \fBrate\fR is used for
870 read vs write separation. If \fBblocksize\fR is a range, the smallest block
871 size is used as the metric.
873 .BI rate_iops_min \fR=\fPint
874 If this rate of I/O is not met, the job will exit. The same format as \fBrate\fR
875 is used for read vs write separation.
877 .BI ratecycle \fR=\fPint
878 Average bandwidth for \fBrate\fR and \fBratemin\fR over this number of
879 milliseconds. Default: 1000ms.
881 .BI latency_target \fR=\fPint
882 If set, fio will attempt to find the max performance point that the given
883 workload will run at while maintaining a latency below this target. The
884 values is given in microseconds. See \fBlatency_window\fR and
885 \fBlatency_percentile\fR.
887 .BI latency_window \fR=\fPint
888 Used with \fBlatency_target\fR to specify the sample window that the job
889 is run at varying queue depths to test the performance. The value is given
892 .BI latency_percentile \fR=\fPfloat
893 The percentage of IOs that must fall within the criteria specified by
894 \fBlatency_target\fR and \fBlatency_window\fR. If not set, this defaults
895 to 100.0, meaning that all IOs must be equal or below to the value set
896 by \fBlatency_target\fR.
898 .BI max_latency \fR=\fPint
899 If set, fio will exit the job if it exceeds this maximum latency. It will exit
902 .BI cpumask \fR=\fPint
903 Set CPU affinity for this job. \fIint\fR is a bitmask of allowed CPUs the job
904 may run on. See \fBsched_setaffinity\fR\|(2).
906 .BI cpus_allowed \fR=\fPstr
907 Same as \fBcpumask\fR, but allows a comma-delimited list of CPU numbers.
909 .BI cpus_allowed_policy \fR=\fPstr
910 Set the policy of how fio distributes the CPUs specified by \fBcpus_allowed\fR
911 or \fBcpumask\fR. Two policies are supported:
916 All jobs will share the CPU set specified.
919 Each job will get a unique CPU from the CPU set.
922 \fBshared\fR is the default behaviour, if the option isn't specified. If
923 \fBsplit\fR is specified, then fio will assign one cpu per job. If not enough
924 CPUs are given for the jobs listed, then fio will roundrobin the CPUs in
929 .BI numa_cpu_nodes \fR=\fPstr
930 Set this job running on specified NUMA nodes' CPUs. The arguments allow
931 comma delimited list of cpu numbers, A-B ranges, or 'all'.
933 .BI numa_mem_policy \fR=\fPstr
934 Set this job's memory policy and corresponding NUMA nodes. Format of
938 .B <mode>[:<nodelist>]
941 is one of the following memory policy:
943 .B default, prefer, bind, interleave, local
946 For \fBdefault\fR and \fBlocal\fR memory policy, no \fBnodelist\fR is
947 needed to be specified. For \fBprefer\fR, only one node is
948 allowed. For \fBbind\fR and \fBinterleave\fR, \fBnodelist\fR allows
949 comma delimited list of numbers, A-B ranges, or 'all'.
951 .BI startdelay \fR=\fPirange
952 Delay start of job for the specified number of seconds. Supports all time
953 suffixes to allow specification of hours, minutes, seconds and
954 milliseconds - seconds are the default if a unit is omitted.
955 Can be given as a range which causes each thread to choose randomly out of the
958 .BI runtime \fR=\fPint
959 Terminate processing after the specified number of seconds.
962 If given, run for the specified \fBruntime\fR duration even if the files are
963 completely read or written. The same workload will be repeated as many times
964 as \fBruntime\fR allows.
966 .BI ramp_time \fR=\fPint
967 If set, fio will run the specified workload for this amount of time before
968 logging any performance numbers. Useful for letting performance settle before
969 logging results, thus minimizing the runtime required for stable results. Note
970 that the \fBramp_time\fR is considered lead in time for a job, thus it will
971 increase the total runtime if a special timeout or runtime is specified.
973 .BI invalidate \fR=\fPbool
974 Invalidate buffer-cache for the file prior to starting I/O. Default: true.
977 Use synchronous I/O for buffered writes. For the majority of I/O engines,
978 this means using O_SYNC. Default: false.
980 .BI iomem \fR=\fPstr "\fR,\fP mem" \fR=\fPstr
981 Allocation method for I/O unit buffer. Allowed values are:
986 Allocate memory with \fBmalloc\fR\|(3).
989 Use shared memory buffers allocated through \fBshmget\fR\|(2).
992 Same as \fBshm\fR, but use huge pages as backing.
995 Use \fBmmap\fR\|(2) for allocation. Uses anonymous memory unless a filename
996 is given after the option in the format `:\fIfile\fR'.
999 Same as \fBmmap\fR, but use huge files as backing.
1002 The amount of memory allocated is the maximum allowed \fBblocksize\fR for the
1003 job multiplied by \fBiodepth\fR. For \fBshmhuge\fR or \fBmmaphuge\fR to work,
1004 the system must have free huge pages allocated. \fBmmaphuge\fR also needs to
1005 have hugetlbfs mounted, and \fIfile\fR must point there. At least on Linux,
1006 huge pages must be manually allocated. See \fB/proc/sys/vm/nr_hugehages\fR
1007 and the documentation for that. Normally you just need to echo an appropriate
1008 number, eg echoing 8 will ensure that the OS has 8 huge pages ready for
1012 .BI iomem_align \fR=\fPint "\fR,\fP mem_align" \fR=\fPint
1013 This indicates the memory alignment of the IO memory buffers. Note that the
1014 given alignment is applied to the first IO unit buffer, if using \fBiodepth\fR
1015 the alignment of the following buffers are given by the \fBbs\fR used. In
1016 other words, if using a \fBbs\fR that is a multiple of the page sized in the
1017 system, all buffers will be aligned to this value. If using a \fBbs\fR that
1018 is not page aligned, the alignment of subsequent IO memory buffers is the
1019 sum of the \fBiomem_align\fR and \fBbs\fR used.
1021 .BI hugepage\-size \fR=\fPint
1022 Defines the size of a huge page. Must be at least equal to the system setting.
1023 Should be a multiple of 1MB. Default: 4MB.
1026 Terminate all jobs when one finishes. Default: wait for each job to finish.
1028 .BI bwavgtime \fR=\fPint
1029 Average bandwidth calculations over the given time in milliseconds. Default:
1032 .BI iopsavgtime \fR=\fPint
1033 Average IOPS calculations over the given time in milliseconds. Default:
1036 .BI create_serialize \fR=\fPbool
1037 If true, serialize file creation for the jobs. Default: true.
1039 .BI create_fsync \fR=\fPbool
1040 \fBfsync\fR\|(2) data file after creation. Default: true.
1042 .BI create_on_open \fR=\fPbool
1043 If true, the files are not created until they are opened for IO by the job.
1045 .BI create_only \fR=\fPbool
1046 If true, fio will only run the setup phase of the job. If files need to be
1047 laid out or updated on disk, only that will be done. The actual job contents
1050 .BI pre_read \fR=\fPbool
1051 If this is given, files will be pre-read into memory before starting the given
1052 IO operation. This will also clear the \fR \fBinvalidate\fR flag, since it is
1053 pointless to pre-read and then drop the cache. This will only work for IO
1054 engines that are seekable, since they allow you to read the same data
1055 multiple times. Thus it will not work on eg network or splice IO.
1057 .BI unlink \fR=\fPbool
1058 Unlink job files when done. Default: false.
1060 .BI loops \fR=\fPint
1061 Specifies the number of iterations (runs of the same workload) of this job.
1064 .BI verify_only \fR=\fPbool
1065 Do not perform the specified workload, only verify data still matches previous
1066 invocation of this workload. This option allows one to check data multiple
1067 times at a later date without overwriting it. This option makes sense only for
1068 workloads that write data, and does not support workloads with the
1069 \fBtime_based\fR option set.
1071 .BI do_verify \fR=\fPbool
1072 Run the verify phase after a write phase. Only valid if \fBverify\fR is set.
1075 .BI verify \fR=\fPstr
1076 Method of verifying file contents after each iteration of the job. Allowed
1081 .B md5 crc16 crc32 crc32c crc32c-intel crc64 crc7 sha256 sha512 sha1 xxhash
1082 Store appropriate checksum in the header of each block. crc32c-intel is
1083 hardware accelerated SSE4.2 driven, falls back to regular crc32c if
1084 not supported by the system.
1087 Write extra information about each I/O (timestamp, block number, etc.). The
1088 block number is verified. See \fBverify_pattern\fR as well.
1091 Pretend to verify. Used for testing internals.
1094 This option can be used for repeated burn-in tests of a system to make sure
1095 that the written data is also correctly read back. If the data direction given
1096 is a read or random read, fio will assume that it should verify a previously
1097 written file. If the data direction includes any form of write, the verify will
1098 be of the newly written data.
1101 .BI verifysort \fR=\fPbool
1102 If true, written verify blocks are sorted if \fBfio\fR deems it to be faster to
1103 read them back in a sorted manner. Default: true.
1105 .BI verifysort_nr \fR=\fPint
1106 Pre-load and sort verify blocks for a read workload.
1108 .BI verify_offset \fR=\fPint
1109 Swap the verification header with data somewhere else in the block before
1110 writing. It is swapped back before verifying.
1112 .BI verify_interval \fR=\fPint
1113 Write the verification header for this number of bytes, which should divide
1114 \fBblocksize\fR. Default: \fBblocksize\fR.
1116 .BI verify_pattern \fR=\fPstr
1117 If set, fio will fill the io buffers with this pattern. Fio defaults to filling
1118 with totally random bytes, but sometimes it's interesting to fill with a known
1119 pattern for io verification purposes. Depending on the width of the pattern,
1120 fio will fill 1/2/3/4 bytes of the buffer at the time(it can be either a
1121 decimal or a hex number). The verify_pattern if larger than a 32-bit quantity
1122 has to be a hex number that starts with either "0x" or "0X". Use with
1125 .BI verify_fatal \fR=\fPbool
1126 If true, exit the job on the first observed verification failure. Default:
1129 .BI verify_dump \fR=\fPbool
1130 If set, dump the contents of both the original data block and the data block we
1131 read off disk to files. This allows later analysis to inspect just what kind of
1132 data corruption occurred. Off by default.
1134 .BI verify_async \fR=\fPint
1135 Fio will normally verify IO inline from the submitting thread. This option
1136 takes an integer describing how many async offload threads to create for IO
1137 verification instead, causing fio to offload the duty of verifying IO contents
1138 to one or more separate threads. If using this offload option, even sync IO
1139 engines can benefit from using an \fBiodepth\fR setting higher than 1, as it
1140 allows them to have IO in flight while verifies are running.
1142 .BI verify_async_cpus \fR=\fPstr
1143 Tell fio to set the given CPU affinity on the async IO verification threads.
1144 See \fBcpus_allowed\fP for the format used.
1146 .BI verify_backlog \fR=\fPint
1147 Fio will normally verify the written contents of a job that utilizes verify
1148 once that job has completed. In other words, everything is written then
1149 everything is read back and verified. You may want to verify continually
1150 instead for a variety of reasons. Fio stores the meta data associated with an
1151 IO block in memory, so for large verify workloads, quite a bit of memory would
1152 be used up holding this meta data. If this option is enabled, fio will write
1153 only N blocks before verifying these blocks.
1155 .BI verify_backlog_batch \fR=\fPint
1156 Control how many blocks fio will verify if verify_backlog is set. If not set,
1157 will default to the value of \fBverify_backlog\fR (meaning the entire queue is
1158 read back and verified). If \fBverify_backlog_batch\fR is less than
1159 \fBverify_backlog\fR then not all blocks will be verified, if
1160 \fBverify_backlog_batch\fR is larger than \fBverify_backlog\fR, some blocks
1161 will be verified more than once.
1163 .BI trim_percentage \fR=\fPint
1164 Number of verify blocks to discard/trim.
1166 .BI trim_verify_zero \fR=\fPbool
1167 Verify that trim/discarded blocks are returned as zeroes.
1169 .BI trim_backlog \fR=\fPint
1170 Trim after this number of blocks are written.
1172 .BI trim_backlog_batch \fR=\fPint
1173 Trim this number of IO blocks.
1175 .BI experimental_verify \fR=\fPbool
1176 Enable experimental verification.
1178 .BI verify_state_save \fR=\fPbool
1179 When a job exits during the write phase of a verify workload, save its
1180 current state. This allows fio to replay up until that point, if the
1181 verify state is loaded for the verify read phase.
1183 .BI verify_state_load \fR=\fPbool
1184 If a verify termination trigger was used, fio stores the current write
1185 state of each thread. This can be used at verification time so that fio
1186 knows how far it should verify. Without this information, fio will run
1187 a full verification pass, according to the settings in the job file used.
1189 .B stonewall "\fR,\fP wait_for_previous"
1190 Wait for preceding jobs in the job file to exit before starting this one.
1191 \fBstonewall\fR implies \fBnew_group\fR.
1194 Start a new reporting group. If not given, all jobs in a file will be part
1195 of the same reporting group, unless separated by a stonewall.
1197 .BI numjobs \fR=\fPint
1198 Number of clones (processes/threads performing the same workload) of this job.
1202 If set, display per-group reports instead of per-job when \fBnumjobs\fR is
1206 Use threads created with \fBpthread_create\fR\|(3) instead of processes created
1207 with \fBfork\fR\|(2).
1209 .BI zonesize \fR=\fPint
1210 Divide file into zones of the specified size in bytes. See \fBzoneskip\fR.
1212 .BI zonerange \fR=\fPint
1213 Give size of an IO zone. See \fBzoneskip\fR.
1215 .BI zoneskip \fR=\fPint
1216 Skip the specified number of bytes when \fBzonesize\fR bytes of data have been
1219 .BI write_iolog \fR=\fPstr
1220 Write the issued I/O patterns to the specified file. Specify a separate file
1221 for each job, otherwise the iologs will be interspersed and the file may be
1224 .BI read_iolog \fR=\fPstr
1225 Replay the I/O patterns contained in the specified file generated by
1226 \fBwrite_iolog\fR, or may be a \fBblktrace\fR binary file.
1228 .BI replay_no_stall \fR=\fPint
1229 While replaying I/O patterns using \fBread_iolog\fR the default behavior
1230 attempts to respect timing information between I/Os. Enabling
1231 \fBreplay_no_stall\fR causes I/Os to be replayed as fast as possible while
1232 still respecting ordering.
1234 .BI replay_redirect \fR=\fPstr
1235 While replaying I/O patterns using \fBread_iolog\fR the default behavior
1236 is to replay the IOPS onto the major/minor device that each IOP was recorded
1237 from. Setting \fBreplay_redirect\fR causes all IOPS to be replayed onto the
1238 single specified device regardless of the device it was recorded from.
1240 .BI write_bw_log \fR=\fPstr
1241 If given, write a bandwidth log of the jobs in this job file. Can be used to
1242 store data of the bandwidth of the jobs in their lifetime. The included
1243 fio_generate_plots script uses gnuplot to turn these text files into nice
1244 graphs. See \fBwrite_lat_log\fR for behaviour of given filename. For this
1245 option, the postfix is _bw.x.log, where x is the index of the job (1..N,
1246 where N is the number of jobs)
1248 .BI write_lat_log \fR=\fPstr
1249 Same as \fBwrite_bw_log\fR, but writes I/O completion latencies. If no
1250 filename is given with this option, the default filename of
1251 "jobname_type.x.log" is used, where x is the index of the job (1..N, where
1252 N is the number of jobs). Even if the filename is given, fio will still
1253 append the type of log.
1255 .BI write_iops_log \fR=\fPstr
1256 Same as \fBwrite_bw_log\fR, but writes IOPS. If no filename is given with this
1257 option, the default filename of "jobname_type.x.log" is used, where x is the
1258 index of the job (1..N, where N is the number of jobs). Even if the filename
1259 is given, fio will still append the type of log.
1261 .BI log_avg_msec \fR=\fPint
1262 By default, fio will log an entry in the iops, latency, or bw log for every
1263 IO that completes. When writing to the disk log, that can quickly grow to a
1264 very large size. Setting this option makes fio average the each log entry
1265 over the specified period of time, reducing the resolution of the log.
1268 .BI log_offset \fR=\fPbool
1269 If this is set, the iolog options will include the byte offset for the IO
1270 entry as well as the other data values.
1272 .BI log_compression \fR=\fPint
1273 If this is set, fio will compress the IO logs as it goes, to keep the memory
1274 footprint lower. When a log reaches the specified size, that chunk is removed
1275 and compressed in the background. Given that IO logs are fairly highly
1276 compressible, this yields a nice memory savings for longer runs. The downside
1277 is that the compression will consume some background CPU cycles, so it may
1278 impact the run. This, however, is also true if the logging ends up consuming
1279 most of the system memory. So pick your poison. The IO logs are saved
1280 normally at the end of a run, by decompressing the chunks and storing them
1281 in the specified log file. This feature depends on the availability of zlib.
1283 .BI log_store_compressed \fR=\fPbool
1284 If set, and \fBlog\fR_compression is also set, fio will store the log files in
1285 a compressed format. They can be decompressed with fio, using the
1286 \fB\-\-inflate-log\fR command line parameter. The files will be stored with a
1289 .BI disable_lat \fR=\fPbool
1290 Disable measurements of total latency numbers. Useful only for cutting
1291 back the number of calls to \fBgettimeofday\fR\|(2), as that does impact performance at
1292 really high IOPS rates. Note that to really get rid of a large amount of these
1293 calls, this option must be used with disable_slat and disable_bw as well.
1295 .BI disable_clat \fR=\fPbool
1296 Disable measurements of completion latency numbers. See \fBdisable_lat\fR.
1298 .BI disable_slat \fR=\fPbool
1299 Disable measurements of submission latency numbers. See \fBdisable_lat\fR.
1301 .BI disable_bw_measurement \fR=\fPbool
1302 Disable measurements of throughput/bandwidth numbers. See \fBdisable_lat\fR.
1304 .BI lockmem \fR=\fPint
1305 Pin the specified amount of memory with \fBmlock\fR\|(2). Can be used to
1306 simulate a smaller amount of memory. The amount specified is per worker.
1308 .BI exec_prerun \fR=\fPstr
1309 Before running the job, execute the specified command with \fBsystem\fR\|(3).
1311 Output is redirected in a file called \fBjobname.prerun.txt\fR
1314 .BI exec_postrun \fR=\fPstr
1315 Same as \fBexec_prerun\fR, but the command is executed after the job completes.
1317 Output is redirected in a file called \fBjobname.postrun.txt\fR
1320 .BI ioscheduler \fR=\fPstr
1321 Attempt to switch the device hosting the file to the specified I/O scheduler.
1323 .BI disk_util \fR=\fPbool
1324 Generate disk utilization statistics if the platform supports it. Default: true.
1326 .BI clocksource \fR=\fPstr
1327 Use the given clocksource as the base of timing. The supported options are:
1331 \fBgettimeofday\fR\|(2)
1334 \fBclock_gettime\fR\|(2)
1337 Internal CPU clock source
1341 \fBcpu\fR is the preferred clocksource if it is reliable, as it is very fast
1342 (and fio is heavy on time calls). Fio will automatically use this clocksource
1343 if it's supported and considered reliable on the system it is running on,
1344 unless another clocksource is specifically set. For x86/x86-64 CPUs, this
1345 means supporting TSC Invariant.
1347 .BI gtod_reduce \fR=\fPbool
1348 Enable all of the \fBgettimeofday\fR\|(2) reducing options (disable_clat, disable_slat,
1349 disable_bw) plus reduce precision of the timeout somewhat to really shrink the
1350 \fBgettimeofday\fR\|(2) call count. With this option enabled, we only do about 0.4% of
1351 the gtod() calls we would have done if all time keeping was enabled.
1353 .BI gtod_cpu \fR=\fPint
1354 Sometimes it's cheaper to dedicate a single thread of execution to just getting
1355 the current time. Fio (and databases, for instance) are very intensive on
1356 \fBgettimeofday\fR\|(2) calls. With this option, you can set one CPU aside for doing
1357 nothing but logging current time to a shared memory location. Then the other
1358 threads/processes that run IO workloads need only copy that segment, instead of
1359 entering the kernel with a \fBgettimeofday\fR\|(2) call. The CPU set aside for doing
1360 these time calls will be excluded from other uses. Fio will manually clear it
1361 from the CPU mask of other jobs.
1363 .BI ignore_error \fR=\fPstr
1364 Sometimes you want to ignore some errors during test in that case you can specify
1365 error list for each error type.
1367 ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST
1369 errors for given error type is separated with ':'.
1370 Error may be symbol ('ENOSPC', 'ENOMEM') or an integer.
1372 Example: ignore_error=EAGAIN,ENOSPC:122 .
1374 This option will ignore EAGAIN from READ, and ENOSPC and 122(EDQUOT) from WRITE.
1376 .BI error_dump \fR=\fPbool
1377 If set dump every error even if it is non fatal, true by default. If disabled
1378 only fatal error will be dumped
1380 .BI profile \fR=\fPstr
1381 Select a specific builtin performance test.
1383 .BI cgroup \fR=\fPstr
1384 Add job to this control group. If it doesn't exist, it will be created.
1385 The system must have a mounted cgroup blkio mount point for this to work. If
1386 your system doesn't have it mounted, you can do so with:
1388 # mount \-t cgroup \-o blkio none /cgroup
1390 .BI cgroup_weight \fR=\fPint
1391 Set the weight of the cgroup to this value. See the documentation that comes
1392 with the kernel, allowed values are in the range of 100..1000.
1394 .BI cgroup_nodelete \fR=\fPbool
1395 Normally fio will delete the cgroups it has created after the job completion.
1396 To override this behavior and to leave cgroups around after the job completion,
1397 set cgroup_nodelete=1. This can be useful if one wants to inspect various
1398 cgroup files after job completion. Default: false
1401 Instead of running as the invoking user, set the user ID to this value before
1402 the thread/process does any work.
1405 Set group ID, see \fBuid\fR.
1407 .BI unit_base \fR=\fPint
1408 Base unit for reporting. Allowed values are:
1412 Use auto-detection (default).
1422 .BI flow_id \fR=\fPint
1423 The ID of the flow. If not specified, it defaults to being a global flow. See
1427 Weight in token-based flow control. If this value is used, then there is a
1428 \fBflow counter\fR which is used to regulate the proportion of activity between
1429 two or more jobs. fio attempts to keep this flow counter near zero. The
1430 \fBflow\fR parameter stands for how much should be added or subtracted to the
1431 flow counter on each iteration of the main I/O loop. That is, if one job has
1432 \fBflow=8\fR and another job has \fBflow=-1\fR, then there will be a roughly
1433 1:8 ratio in how much one runs vs the other.
1435 .BI flow_watermark \fR=\fPint
1436 The maximum value that the absolute value of the flow counter is allowed to
1437 reach before the job must wait for a lower value of the counter.
1439 .BI flow_sleep \fR=\fPint
1440 The period of time, in microseconds, to wait after the flow watermark has been
1441 exceeded before retrying operations
1443 .BI clat_percentiles \fR=\fPbool
1444 Enable the reporting of percentiles of completion latencies.
1446 .BI percentile_list \fR=\fPfloat_list
1447 Overwrite the default list of percentiles for completion
1448 latencies. Each number is a floating number in the range (0,100], and
1449 the maximum length of the list is 20. Use ':' to separate the
1450 numbers. For example, \-\-percentile_list=99.5:99.9 will cause fio to
1451 report the values of completion latency below which 99.5% and 99.9% of
1452 the observed latencies fell, respectively.
1453 .SS "Ioengine Parameters List"
1454 Some parameters are only valid when a specific ioengine is in use. These are
1455 used identically to normal parameters, with the caveat that when used on the
1456 command line, they must come after the ioengine.
1458 .BI (cpu)cpuload \fR=\fPint
1459 Attempt to use the specified percentage of CPU cycles.
1461 .BI (cpu)cpuchunks \fR=\fPint
1462 Split the load into cycles of the given time. In microseconds.
1464 .BI (cpu)exit_on_io_done \fR=\fPbool
1465 Detect when IO threads are done, then exit.
1467 .BI (libaio)userspace_reap
1468 Normally, with the libaio engine in use, fio will use
1469 the io_getevents system call to reap newly returned events.
1470 With this flag turned on, the AIO ring will be read directly
1471 from user-space to reap events. The reaping mode is only
1472 enabled when polling for a minimum of 0 events (eg when
1473 iodepth_batch_complete=0).
1475 .BI (net,netsplice)hostname \fR=\fPstr
1476 The host name or IP address to use for TCP or UDP based IO.
1477 If the job is a TCP listener or UDP reader, the hostname is not
1478 used and must be omitted unless it is a valid UDP multicast address.
1480 .BI (net,netsplice)port \fR=\fPint
1481 The TCP or UDP port to bind to or connect to. If this is used with
1482 \fBnumjobs\fR to spawn multiple instances of the same job type, then
1483 this will be the starting port number since fio will use a range of ports.
1485 .BI (net,netsplice)interface \fR=\fPstr
1486 The IP address of the network interface used to send or receive UDP multicast
1489 .BI (net,netsplice)ttl \fR=\fPint
1490 Time-to-live value for outgoing UDP multicast packets. Default: 1
1492 .BI (net,netsplice)nodelay \fR=\fPbool
1493 Set TCP_NODELAY on TCP connections.
1495 .BI (net,netsplice)protocol \fR=\fPstr "\fR,\fP proto" \fR=\fPstr
1496 The network protocol to use. Accepted values are:
1501 Transmission control protocol
1504 Transmission control protocol V6
1507 User datagram protocol
1510 User datagram protocol V6
1516 When the protocol is TCP or UDP, the port must also be given,
1517 as well as the hostname if the job is a TCP listener or UDP
1518 reader. For unix sockets, the normal filename option should be
1519 used and the port is invalid.
1522 .BI (net,netsplice)listen
1523 For TCP network connections, tell fio to listen for incoming
1524 connections rather than initiating an outgoing connection. The
1525 hostname must be omitted if this option is used.
1527 .BI (net, pingpong) \fR=\fPbool
1528 Normally a network writer will just continue writing data, and a network reader
1529 will just consume packets. If pingpong=1 is set, a writer will send its normal
1530 payload to the reader, then wait for the reader to send the same payload back.
1531 This allows fio to measure network latencies. The submission and completion
1532 latencies then measure local time spent sending or receiving, and the
1533 completion latency measures how long it took for the other end to receive and
1534 send back. For UDP multicast traffic pingpong=1 should only be set for a single
1535 reader when multiple readers are listening to the same address.
1537 .BI (net, window_size) \fR=\fPint
1538 Set the desired socket buffer size for the connection.
1540 .BI (net, mss) \fR=\fPint
1541 Set the TCP maximum segment size (TCP_MAXSEG).
1543 .BI (e4defrag,donorname) \fR=\fPstr
1544 File will be used as a block donor (swap extents between files)
1546 .BI (e4defrag,inplace) \fR=\fPint
1547 Configure donor file block allocation strategy
1550 Preallocate donor's file on init
1553 allocate space immediately inside defragment event, and free right after event
1556 .BI (rbd)rbdname \fR=\fPstr
1557 Specifies the name of the RBD.
1559 .BI (rbd)pool \fR=\fPstr
1560 Specifies the name of the Ceph pool containing the RBD.
1562 .BI (rbd)clientname \fR=\fPstr
1563 Specifies the username (without the 'client.' prefix) used to access the Ceph cluster.
1565 While running, \fBfio\fR will display the status of the created jobs. For
1569 Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s]
1572 The characters in the first set of brackets denote the current status of each
1573 threads. The possible values are:
1579 Setup but not started.
1585 Initialized, waiting.
1588 Running, doing sequential reads.
1591 Running, doing random reads.
1594 Running, doing sequential writes.
1597 Running, doing random writes.
1600 Running, doing mixed sequential reads/writes.
1603 Running, doing mixed random reads/writes.
1606 Running, currently waiting for \fBfsync\fR\|(2).
1609 Running, verifying written data.
1612 Exited, not reaped by main thread.
1615 Exited, thread reaped.
1619 The second set of brackets shows the estimated completion percentage of
1620 the current group. The third set shows the read and write I/O rate,
1621 respectively. Finally, the estimated run time of the job is displayed.
1623 When \fBfio\fR completes (or is interrupted by Ctrl-C), it will show data
1624 for each thread, each group of threads, and each disk, in that order.
1626 Per-thread statistics first show the threads client number, group-id, and
1627 error code. The remaining figures are as follows:
1631 Number of megabytes of I/O performed.
1634 Average data rate (bandwidth).
1640 Submission latency minimum, maximum, average and standard deviation. This is
1641 the time it took to submit the I/O.
1644 Completion latency minimum, maximum, average and standard deviation. This
1645 is the time between submission and completion.
1648 Bandwidth minimum, maximum, percentage of aggregate bandwidth received, average
1649 and standard deviation.
1652 CPU usage statistics. Includes user and system time, number of context switches
1653 this thread went through and number of major and minor page faults.
1656 Distribution of I/O depths. Each depth includes everything less than (or equal)
1657 to it, but greater than the previous depth.
1660 Number of read/write requests issued, and number of short read/write requests.
1663 Distribution of I/O completion latencies. The numbers follow the same pattern
1667 The group statistics show:
1672 Number of megabytes I/O performed.
1675 Aggregate bandwidth of threads in the group.
1678 Minimum average bandwidth a thread saw.
1681 Maximum average bandwidth a thread saw.
1684 Shortest runtime of threads in the group.
1687 Longest runtime of threads in the group.
1691 Finally, disk statistics are printed with reads first:
1696 Number of I/Os performed by all groups.
1699 Number of merges in the I/O scheduler.
1702 Number of ticks we kept the disk busy.
1705 Total time spent in the disk queue.
1712 It is also possible to get fio to dump the current output while it is
1713 running, without terminating the job. To do that, send fio the \fBUSR1\fR
1716 If the \fB\-\-minimal\fR / \fB\-\-append-terse\fR options are given, the
1717 results will be printed/appended in a semicolon-delimited format suitable for
1719 A job description (if provided) follows on a new line. Note that the first
1720 number in the line is the version number. If the output has to be changed
1721 for some reason, this number will be incremented by 1 to signify that
1722 change. The fields are:
1725 .B terse version, fio version, jobname, groupid, error
1729 .B Total I/O \fR(KB)\fP, bandwidth \fR(KB/s)\fP, IOPS, runtime \fR(ms)\fP
1733 .B min, max, mean, standard deviation
1737 .B min, max, mean, standard deviation
1739 Completion latency percentiles (20 fields):
1741 .B Xth percentile=usec
1745 .B min, max, mean, standard deviation
1749 .B min, max, aggregate percentage of total, mean, standard deviation
1755 .B Total I/O \fR(KB)\fP, bandwidth \fR(KB/s)\fP, IOPS, runtime \fR(ms)\fP
1759 .B min, max, mean, standard deviation
1763 .B min, max, mean, standard deviation
1765 Completion latency percentiles (20 fields):
1767 .B Xth percentile=usec
1771 .B min, max, mean, standard deviation
1775 .B min, max, aggregate percentage of total, mean, standard deviation
1781 .B user, system, context switches, major page faults, minor page faults
1784 IO depth distribution:
1786 .B <=1, 2, 4, 8, 16, 32, >=64
1789 IO latency distribution:
1793 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
1797 .B <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
1801 Disk utilization (1 for each disk used):
1803 .B name, read ios, write ios, read merges, write merges, read ticks, write ticks, read in-queue time, write in-queue time, disk utilization percentage
1806 Error Info (dependent on continue_on_error, default off):
1808 .B total # errors, first error code
1811 .B text description (if provided in config - appears on newline)
1814 Normally you would run fio as a stand-alone application on the machine
1815 where the IO workload should be generated. However, it is also possible to
1816 run the frontend and backend of fio separately. This makes it possible to
1817 have a fio server running on the machine(s) where the IO workload should
1818 be running, while controlling it from another machine.
1820 To start the server, you would do:
1822 \fBfio \-\-server=args\fR
1824 on that machine, where args defines what fio listens to. The arguments
1825 are of the form 'type:hostname or IP:port'. 'type' is either 'ip' (or ip4)
1826 for TCP/IP v4, 'ip6' for TCP/IP v6, or 'sock' for a local unix domain
1827 socket. 'hostname' is either a hostname or IP address, and 'port' is the port to
1828 listen to (only valid for TCP/IP, not a local socket). Some examples:
1832 Start a fio server, listening on all interfaces on the default port (8765).
1834 2) fio \-\-server=ip:hostname,4444
1836 Start a fio server, listening on IP belonging to hostname and on port 4444.
1838 3) fio \-\-server=ip6:::1,4444
1840 Start a fio server, listening on IPv6 localhost ::1 and on port 4444.
1842 4) fio \-\-server=,4444
1844 Start a fio server, listening on all interfaces on port 4444.
1846 5) fio \-\-server=1.2.3.4
1848 Start a fio server, listening on IP 1.2.3.4 on the default port.
1850 6) fio \-\-server=sock:/tmp/fio.sock
1852 Start a fio server, listening on the local socket /tmp/fio.sock.
1854 When a server is running, you can connect to it from a client. The client
1857 fio \-\-local-args \-\-client=server \-\-remote-args <job file(s)>
1859 where \-\-local-args are arguments that are local to the client where it is
1860 running, 'server' is the connect string, and \-\-remote-args and <job file(s)>
1861 are sent to the server. The 'server' string follows the same format as it
1862 does on the server side, to allow IP/hostname/socket and port strings.
1863 You can connect to multiple clients as well, to do that you could run:
1865 fio \-\-client=server2 \-\-client=server2 <job file(s)>
1867 If the job file is located on the fio server, then you can tell the server
1868 to load a local file as well. This is done by using \-\-remote-config:
1870 fio \-\-client=server \-\-remote-config /path/to/file.fio
1872 Then the fio serer will open this local (to the server) job file instead
1873 of being passed one from the client.
1877 was written by Jens Axboe <jens.axboe@oracle.com>,
1878 now Jens Axboe <axboe@fb.com>.
1880 This man page was written by Aaron Carroll <aaronc@cse.unsw.edu.au> based
1881 on documentation by Jens Axboe.
1882 .SH "REPORTING BUGS"
1883 Report bugs to the \fBfio\fR mailing list <fio@vger.kernel.org>.
1886 For further documentation see \fBHOWTO\fR and \fBREADME\fR.
1888 Sample jobfiles are available in the \fBexamples\fR directory.
projects / fio.git / blob