5. Detailed list of parameters
6. Normal output
7. Terse output
-
+8. Trace file format
1.0 Overview and history
------------------------
1k:4k. If the option allows two sets of ranges, they can be
specified with a ',' or '/' delimiter: 1k-4k/8k-32k. Also see
int.
+float_list A list of floating numbers, separated by a ':' character.
With the above in mind, here follows the complete list of fio job
parameters.
files between threads in a job or several jobs, specify
a filename for each of them to override the default. If
the ioengine used is 'net', the filename is the host, port,
- and protocol to use in the format of =host/port/protocol.
+ and protocol to use in the format of =host,port,protocol.
See ioengine=net for more. If the ioengine is file based, you
can specify a number of files by separating the names with a
':' colon. So if you wanted a job to open /dev/sda and /dev/sdb
as the two working files, you would use
- filename=/dev/sda:/dev/sdb. If the wanted filename does need to
- include a colon, then escape that with a '\' character. For
- instance, if the filename is "/dev/dsk/foo@3,0:c", then you would
- use filename="/dev/dsk/foo@3,0\:c". '-' is a reserved name,
- meaning stdin or stdout. Which of the two depends on the read/write
- direction set.
+ filename=/dev/sda:/dev/sdb. On Windows, disk devices are accessed
+ as \\.\PhysicalDrive0 for the first device, \\.\PhysicalDrive1
+ for the second etc. If the wanted filename does need to
+ include a colon, then escape that with a '\' character.
+ For instance, if the filename is "/dev/dsk/foo@3,0:c",
+ then you would use filename="/dev/dsk/foo@3,0\:c".
+ '-' is a reserved name, meaning stdin or stdout. Which of the
+ two depends on the read/write direction set.
opendir=str Tell fio to recursively add any file it can find in this
directory and down the file system tree.
For the mixed io types, the default is to split them 50/50.
For certain types of io the result may still be skewed a bit,
since the speed may be different. It is possible to specify
- a number of IO's to do before getting a new offset - this
- is only useful for random IO, where fio would normally
- generate a new random offset for every IO. If you append
- eg 8 to randread, you would get a new random offset for
+ a number of IO's to do before getting a new offset, this is
+ one by appending a ':<nr>' to the end of the string given.
+ For a random read, it would look like 'rw=randread:8' for
+ passing in an offset modifier with a value of 8. If the
+ postfix is used with a sequential IO pattern, then the value
+ specified will be added to the generated offset for each IO.
+ For instance, using rw=write:4k will skip 4k for every
+ write. It turns sequential IO into sequential IO with holes.
+ See the 'rw_sequencer' option.
+
+rw_sequencer=str If an offset modifier is given by appending a number to
+ the rw=<str> line, then this option controls how that
+ number modifies the IO offset being generated. Accepted
+ values are:
+
+ sequential Generate sequential offset
+ identical Generate the same offset
+
+ 'sequential' is only useful for random IO, where fio would
+ normally generate a new random offset for every IO. If you
+ append eg 8 to randread, you would get a new random offset for
every 8 IO's. The result would be a seek for only every 8
IO's, instead of for every IO. Use rw=randread:8 to specify
- that.
+ that. As sequential IO is already sequential, setting
+ 'sequential' for that would not result in any differences.
+ 'identical' behaves in a similar fashion, except it sends
+ the same offset 8 number of times before generating a new
+ offset.
kb_base=int The base unit for a kilobyte. The defacto base is 2^10, 1024.
Storage manufacturers like to use 10^3 or 1000 as a base
randrepeat=bool For random IO workloads, seed the generator in a predictable
way so that results are repeatable across repetitions.
-fallocate=bool By default, fio will use fallocate() to advise the system
- of the size of the file we are going to write. This can be
- turned off with fallocate=0. May not be available on all
- supported platforms.
+use_os_rand=bool Fio can either use the random generator supplied by the OS
+ to generator random offsets, or it can use it's own internal
+ generator (based on Tausworthe). Default is to use the
+ internal generator, which is often of better quality and
+ faster.
+
+fallocate=str Whether pre-allocation is performed when laying down files.
+ Accepted values are:
+
+ none Do not pre-allocate space
+ posix Pre-allocate via posix_fallocate()
+ keep Pre-allocate via fallocate() with
+ FALLOC_FL_KEEP_SIZE set
+ 0 Backward-compatible alias for 'none'
+ 1 Backward-compatible alias for 'posix'
+
+ May not be available on all supported platforms. 'keep' is only
+ available on Linux.If using ZFS on Solaris this must be set to
+ 'none' because ZFS doesn't support it. Default: 'posix'.
fadvise_hint=bool By default, fio will use fadvise() to advise the kernel
on what IO patterns it is likely to issue. Sometimes you
limited by other options (such as 'runtime', for instance).
Unless specific nrfiles and filesize options are given,
fio will divide this size between the available files
- specified by the job.
+ specified by the job. If not set, fio will use the full
+ size of the given files or devices. If the the files
+ do not exist, size must be given. It is also possible to
+ give size as a percentage between 1 and 100. If size=20%
+ is given, fio will use 20% of the full size of the given
+ files or devices.
filesize=int Individual file sizes. May be a range, in which case fio
will select sizes for files at random within the given range
and limited to 'size' in total (if that is given). If not
given, each created file is the same size.
-fill_device=bool Sets size to something really large and waits for ENOSPC (no
+fill_device=bool
+fill_fs=bool Sets size to something really large and waits for ENOSPC (no
space left on device) as the terminating condition. Only makes
sense with sequential write. For a read workload, the mount
- point will be filled first then IO started on the result.
+ point will be filled first then IO started on the result. This
+ option doesn't make sense if operating on a raw device node,
+ since the size of that is already known by the file system.
+ Additionally, writing beyond end-of-device will not return
+ ENOSPC there.
blocksize=int
bs=int The block size used for the io units. Defaults to 4k. Values
isn't specified, naturally. If data verification is enabled,
refill_buffers is also automatically enabled.
+scramble_buffers=bool If refill_buffers is too costly and the target is
+ using data deduplication, then setting this option will
+ slightly modify the IO buffer contents to defeat normal
+ de-dupe attempts. This is not enough to defeat more clever
+ block compression attempts, but it will stop naive dedupe of
+ blocks. Default: true.
+
nrfiles=int Number of files to use for this job. Defaults to 1.
openfiles=int Number of files to keep open at the same time. Defaults to
libaio Linux native asynchronous io. Note that Linux
may only support queued behaviour with
non-buffered IO (set direct=1 or buffered=0).
+ This engine also has a sub-option,
+ userspace_reap. To set it, use
+ ioengine=libaio:userspace_reap. Normally, with
+ the libaio engine in use, fio will use the
+ io_getevents system call to reap newly returned
+ events. With this flag turned on, the AIO ring
+ will be read directly from user-space to reap
+ events. The reaping mode is only enabled when
+ polling for a minimum of 0 events (eg when
+ iodepth_batch_complete=0).
posixaio glibc posix asynchronous io.
solarisaio Solaris native asynchronous io.
+ windowsaio Windows native asynchronous io.
+
mmap File is memory mapped and data copied
to/from using memcpy(3).
for more info on GUASI.
+ rdma The RDMA I/O engine supports both RDMA
+ memory semantics (RDMA_WRITE/RDMA_READ) and
+ channel semantics (Send/Recv) for the
+ InfiniBand, RoCE and iWARP protocols.
+
external Prefix to specify loading an external
IO engine object file. Append the engine
filename, eg ioengine=external:/tmp/foo.o
iodepth=int This defines how many io units to keep in flight against
the file. The default is 1 for each file defined in this
job, can be overridden with a larger value for higher
- concurrency.
+ concurrency. Note that increasing iodepth beyond 1 will not
+ affect synchronous ioengines (except for small degress when
+ verify_async is in use). Even async engines may impose OS
+ restrictions causing the desired depth not to be achieved.
+ This may happen on Linux when using libaio and not setting
+ direct=1, since buffered IO is not async on that OS. Keep an
+ eye on the IO depth distribution in the fio output to verify
+ that the achieved depth is as expected. Default: 1.
iodepth_batch_submit=int
iodepth_batch=int This defines how many pieces of IO to submit at once.
the depth drain down to 4 before starting to fill it again.
direct=bool If value is true, use non-buffered io. This is usually
- O_DIRECT.
+ O_DIRECT. Note that ZFS on Solaris doesn't support direct io.
buffered=bool If value is true, use buffered io. This is the opposite
of the 'direct' option. Defaults to true.
blocksizes (via bsrange=) are used, since fio only tracks
complete rewrites of blocks.
-softrandommap See norandommap. If fio runs with the random block map enabled
- and it fails to allocate the map, if this option is set it
- will continue without a random block map. As coverage will
- not be as complete as with random maps, this option is
+softrandommap=bool See norandommap. If fio runs with the random block map
+ enabled and it fails to allocate the map, if this option is
+ set it will continue without a random block map. As coverage
+ will not be as complete as with random maps, this option is
disabled by default.
nice=int Run the job with the given nice value. See man nice(2).
bwavgtime=int Average the calculated bandwidth over the given time. Value
is specified in milliseconds.
+iopsavgtime=int Average the calculated IOPS over the given time. Value
+ is specified in milliseconds.
+
create_serialize=bool If true, serialize the file creating for the jobs.
This may be handy to avoid interleaving of data
files, which may greatly depend on the filesystem
option is set, fio will exit the job on the first observed
failure.
+verify_dump=bool If set, dump the contents of both the original data
+ block and the data block we read off disk to files. This
+ allows later analysis to inspect just what kind of data
+ corruption occurred. On by default.
+
verify_async=int Fio will normally verify IO inline from the submitting
thread. This option takes an integer describing how many
async offload threads to create for IO verification instead,
associated with an IO block in memory, so for large
verify workloads, quite a bit of memory would be used up
holding this meta data. If this option is enabled, fio
+ will write only N blocks before verifying these blocks.
+
will verify the previously written blocks before continuing
to write new ones.
verify_backlog_batch=int Control how many blocks fio will verify
if verify_backlog is set. If not set, will default to
the value of verify_backlog (meaning the entire queue
- is read back and verified).
+ is read back and verified). If verify_backlog_batch is
+ less than verify_backlog then not all blocks will be verified,
+ if verify_backlog_batch is larger than verify_backlog, some
+ blocks will be verified more than once.
-stonewall Wait for preceeding jobs in the job file to exit, before
+stonewall
+wait_for_previous Wait for preceeding jobs in the job file to exit, before
starting this one. Can be used to insert serialization
points in the job file. A stone wall also implies starting
a new reporting group.
io on zones of a file.
write_iolog=str Write the issued io patterns to the specified file. See
- read_iolog.
+ read_iolog. Specify a separate file for each job, otherwise
+ the iologs will be interspersed and the file may be corrupt.
read_iolog=str Open an iolog with the specified file name and replay the
io patterns it contains. This can be used to store a
for how to capture such logging data. For blktrace replay,
the file needs to be turned into a blkparse binary data
file first (blkparse <device> -o /dev/null -d file_for_fio.bin).
+
+replay_no_stall=int When replaying I/O with read_iolog the default behavior
+ is to attempt to respect the time stamps within the log and
+ replay them with the appropriate delay between IOPS. By
+ setting this variable fio will not respect the timestamps and
+ attempt to replay them as fast as possible while still
+ respecting ordering. The result is the same I/O pattern to a
+ given device, but different timings.
+
+replay_redirect=str While replaying I/O patterns using read_iolog the
+ default behavior is to replay the IOPS onto the major/minor
+ device that each IOP was recorded from. This is sometimes
+ undesireable because on a different machine those major/minor
+ numbers can map to a different device. Changing hardware on
+ the same system can also result in a different major/minor
+ mapping. Replay_redirect causes all IOPS to be replayed onto
+ the single specified device regardless of the device it was
+ recorded from. i.e. replay_redirect=/dev/sdc would cause all
+ IO in the blktrace to be replayed onto /dev/sdc. This means
+ multiple devices will be replayed onto a single, if the trace
+ contains multiple devices. If you want multiple devices to be
+ replayed concurrently to multiple redirected devices you must
+ blkparse your trace into separate traces and replay them with
+ independent fio invocations. Unfortuantely this also breaks
+ the strict time ordering between multiple device accesses.
write_bw_log=str If given, write a bandwidth log of the jobs in this job
file. Can be used to store data of the bandwidth of the
and foo_lat.log. This helps fio_generate_plot fine the logs
automatically.
+write_bw_log=str If given, write an IOPS log of the jobs in this job
+ file. See write_bw_log.
+
lockmem=int Pin down the specified amount of memory with mlock(2). Can
potentially be used instead of removing memory or booting
with less memory to simulate a smaller amount of memory.
disable_bw=bool Disable measurements of throughput/bandwidth numbers. See
disable_lat.
+clat_percentiles=bool Enable the reporting of percentiles of
+ completion latencies.
+
+percentile_list=float_list Overwrite the default list of percentiles
+ for completion latencies. Each number is a floating
+ number in the range (0,100], and the maximum length of
+ the list is 20. Use ':' to separate the numbers, and
+ list the numbers in ascending order. For example,
+ --percentile_list=99.5:99.9 will cause fio to report
+ the values of completion latency below which 99.5% and
+ 99.9% of the observed latencies fell, respectively.
+
gtod_reduce=bool Enable all of the gettimeofday() reducing options
(disable_clat, disable_slat, disable_bw) plus reduce
precision of the timeout somewhat to really shrink
direction, the output looks like:
Client1 (g=0): err= 0:
- write: io= 32MB, bw= 666KB/s, runt= 50320msec
+ write: io= 32MB, bw= 666KB/s, iops=89 , runt= 50320msec
slat (msec): min= 0, max= 136, avg= 0.03, stdev= 1.92
clat (msec): min= 0, max= 631, avg=48.50, stdev=86.82
bw (KB/s) : min= 0, max= 1196, per=51.00%, avg=664.02, stdev=681.68
io= Number of megabytes io performed
bw= Average bandwidth rate
+iops= Average IOs performed per second
runt= The runtime of that thread
slat= Submission latency (avg being the average, stdev being the
standard deviation). This is the time it took to submit
of the results, fio can output the results in a semicolon separated format.
The format is one long line of values, such as:
-client1;0;0;1906777;1090804;1790;0;0;0.000000;0.000000;0;0;0.000000;0.000000;929380;1152890;25.510151%;1078276.333333;128948.113404;0;0;0;0;0;0.000000;0.000000;0;0;0.000000;0.000000;0;0;0.000000%;0.000000;0.000000;100.000000%;0.000000%;324;100.0%;0.0%;0.0%;0.0%;0.0%;0.0%;0.0%;100.0%;0.0%;0.0%;0.0%;0.0%;0.0%
-;0.0%;0.0%;0.0%;0.0%;0.0%
+2;card0;0;0;7139336;121836;60004;1;10109;27.932460;116.933948;220;126861;3495.446807;1085.368601;226;126864;3523.635629;1089.012448;24063;99944;50.275485%;59818.274627;5540.657370;7155060;122104;60004;1;8338;29.086342;117.839068;388;128077;5032.488518;1234.785715;391;128085;5061.839412;1236.909129;23436;100928;50.287926%;59964.832030;5644.844189;14.595833%;19.394167%;123706;0;7313;0.1%;0.1%;0.1%;0.1%;0.1%;0.1%;100.0%;0.00%;0.00%;0.00%;0.00%;0.00%;0.00%;0.01%;0.02%;0.05%;0.16%;6.04%;40.40%;52.68%;0.64%;0.01%;0.00%;0.01%;0.00%;0.00%;0.00%;0.00%;0.00%
+A description of this job goes here.
-To enable terse output, use the --minimal command line option.
+The job description (if provided) follows on a second line.
+
+To enable terse output, use the --minimal command line option. The first
+value is the version of the terse output format. If the output has to
+be changed for some reason, this number will be incremented by 1 to
+signify that change.
Split up, the format is as follows:
- jobname, groupid, error
+ terse version, fio version, jobname, groupid, error
READ status:
- KB IO, bandwidth (KB/sec), runtime (msec)
+ Total IO (KB), bandwidth (KB/sec), IOPS, runtime (msec)
Submission latency: min, max, mean, deviation
Completion latency: min, max, mean, deviation
+ Completion latency percentiles: 20 fields (see below)
+ Total latency: min, max, mean, deviation
Bw: min, max, aggregate percentage of total, mean, deviation
WRITE status:
- KB IO, bandwidth (KB/sec), runtime (msec)
+ Total IO (KB), bandwidth (KB/sec), IOPS, runtime (msec)
Submission latency: min, max, mean, deviation
Completion latency: min, max, mean, deviation
+ Completion latency percentiles: 20 fields (see below)
+ Total latency: min, max, mean, deviation
Bw: min, max, aggregate percentage of total, mean, deviation
CPU usage: user, system, context switches, major faults, minor faults
IO depths: <=1, 2, 4, 8, 16, 32, >=64
- IO latencies: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, >=2000
- Text description
+ IO latencies microseconds: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000
+ IO latencies milliseconds: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, 2000, >=2000
+ Disk utilization: Disk name, Read ios, write ios,
+ Read merges, write merges,
+ Read ticks, write ticks,
+ Time spent in queue, disk utilization percentage
+ Additional Info (dependant on continue_on_error, default off): total # errors, first error code
+
+ Additional Info (dependant on description being set): Text description
+
+Completion latency percentiles can be a grouping of up to 20 sets, so
+for the terse output fio writes all of them. Each field will look like this:
+
+ 1.00%=6112
+
+which is the Xth percentile, and the usec latency associated with it.
+
+For disk utilization, all disks used by fio are shown. So for each disk
+there will be a disk utilization section.
+
+
+8.0 Trace file format
+---------------------
+There are two trace file format that you can encounter. The older (v1) format
+is unsupported since version 1.20-rc3 (March 2008). It will still be described
+below in case that you get an old trace and want to understand it.
+
+In any case the trace is a simple text file with a single action per line.
+
+
+8.1 Trace file format v1
+------------------------
+Each line represents a single io action in the following format:
+
+rw, offset, length
+
+where rw=0/1 for read/write, and the offset and length entries being in bytes.
+
+This format is not supported in Fio versions => 1.20-rc3.
+
+
+8.2 Trace file format v2
+------------------------
+The second version of the trace file format was added in Fio version 1.17.
+It allows to access more then one file per trace and has a bigger set of
+possible file actions.
+
+The first line of the trace file has to be:
+
+fio version 2 iolog
+
+Following this can be lines in two different formats, which are described below.
+
+The file management format:
+
+filename action
+
+The filename is given as an absolute path. The action can be one of these:
+
+add Add the given filename to the trace
+open Open the file with the given filename. The filename has to have
+ been added with the add action before.
+close Close the file with the given filename. The file has to have been
+ opened before.
+
+
+The file io action format:
+
+filename action offset length
+
+The filename is given as an absolute path, and has to have been added and opened
+before it can be used with this format. The offset and length are given in
+bytes. The action can be one of these:
+wait Wait for 'offset' microseconds. Everything below 100 is discarded.
+read Read 'length' bytes beginning from 'offset'
+write Write 'length' bytes beginning from 'offset'
+sync fsync() the file
+datasync fdatasync() the file
+trim trim the given file from the given 'offset' for 'length' bytes
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