fio

Langue: en

Version: 369978 (fedora - 01/12/10)

Section: 1 (Commandes utilisateur)

NAME

fio - flexible I/O tester

SYNOPSIS

fio [options] [jobfile]...

DESCRIPTION

fio is a tool that will spawn a number of threads or processes doing a particular type of I/O action as specified by the user. The typical use of fio is to write a job file matching the I/O load one wants to simulate.

OPTIONS

--output=filename
Write output to filename.
--timeout=timeout
Limit run time to timeout seconds.
--latency-log
Generate per-job latency logs.
--bandwidth-log
Generate per-job bandwidth logs.
--minimal
Print statistics in a terse, semicolon-delimited format.
--showcmd=jobfile
Convert jobfile to a set of command-line options.
--readonly
Enable read-only safety checks.
--eta=when
Specifies when real-time ETA estimate should be printed. when may be one of `always', `never' or `auto'.
--section=sec
Only run section sec from job file.
--cmdhelp=command
Print help information for command. May be `all' for all commands.
--debug=type
Enable verbose tracing of various fio actions. May be `all' for all types or individual types seperated by a comma (eg --debug=io,file). `help' will list all available tracing options.
--help
Display usage information and exit.
--version
Display version information and exit.

JOB FILE FORMAT

Job files are in `ini' format. They consist of one or more job definitions, which begin with a job name in square brackets and extend to the next job name. The job name can be any ASCII string except `global', which has a special meaning. Following the job name is a sequence of zero or more parameters, one per line, that define the behavior of the job. Any line starting with a `;' or `#' character is considered a comment and ignored. If jobfile is specified as `-', the job file will be read from standard input.

Global Section

The global section contains default parameters for jobs specified in the job file. A job is only affected by global sections residing above it, and there may be any number of global sections. Specific job definitions may override any parameter set in global sections.

JOB PARAMETERS

Types

Some parameters may take arguments of a specific type. The types used are:
str
String: a sequence of alphanumeric characters.
int
SI integer: a whole number, possibly containing a suffix denoting the base unit of the value. Accepted suffixes are `k', 'M', 'G', 'T', and 'P', denoting kilo (1024), mega (1024^2), giga (1024^3), tera (1024^4), and peta (1024^5) respectively. The suffix is not case sensitive. If prefixed with '0x', the value is assumed to be base 16 (hexadecimal). A suffix may include a trailing by using 'KiB', 'MiB', 'GiB', etc. This is useful for disk drives where values are often given in base 10 values. Specifying '30GiB' will get you 30*1000^3 bytes.
bool
Boolean: a true or false value. `0' denotes false, `1' denotes true.
irange
Integer range: a range of integers specified in the format lower:upper or lower-upper. lower and upper may contain a suffix as described above. If an option allows two sets of ranges, they are separated with a `,' or `/' character. For example: `8-8k/8M-4G'.

Parameter List

name=str
May be used to override the job name. On the command line, this parameter has the special purpose of signalling the start of a new job.
description=str
Human-readable description of the job. It is printed when the job is run, but otherwise has no special purpose.
directory=str
Prefix filenames with this directory. Used to place files in a location other than `./'.
filename=str
fio normally makes up a file name based on the job name, thread number, and file number. If you want to share files between threads in a job or several jobs, specify a filename for each of them to override the default. If the I/O engine used is `net', filename is the host and port to connect to in the format host/port. If the I/O engine is file-based, you can specify a number of files by separating the names with a `:' character. `-' is a reserved name, meaning stdin or stdout, depending on the read/write direction set.
lockfile=str
Fio defaults to not locking any files before it does IO to them. If a file or file descriptor is shared, fio can serialize IO to that file to make the end result consistent. This is usual for emulating real workloads that share files. The lock modes are:
none
No locking. This is the default.
exclusive
Only one thread or process may do IO at the time, excluding all others.
readwrite
Read-write locking on the file. Many readers may access the file at the same time, but writes get exclusive access.
The option may be post-fixed with a lock batch number. If set, then each thread/process may do that amount of IOs to the file before giving up the lock. Since lock acquisition is expensive, batching the lock/unlocks will speed up IO.
opendir=str Recursively open any files below directory str.
readwrite=str, rw=str
Type of I/O pattern. Accepted values are:
read
Sequential reads.
write
Sequential writes.
randread
Random reads.
randwrite
Random writes.
rw
Mixed sequential reads and writes.
randrw
Mixed random reads and writes.
For mixed I/O, the default split is 50/50. For random I/O, the number of I/Os to perform before getting a new offset can be specified by appending `:int' to the pattern type. The default is 1.
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 ten unit instead, for obvious reasons. Allow values are 1024 or 1000, with 1024 being the default.
randrepeat=bool
Seed the random number generator in a predictable way so results are repeatable across runs. Default: true.
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.
fadvise_hint=bool
Disable use of posix_fadvise(2) to advise the kernel what I/O patterns are likely to be issued. Default: true.
size=int
Total size of I/O for this job. fio will run until this many bytes have been transfered, unless limited by other options (runtime, for instance). Unless nr_files and filesize options are given, this amount will be divided between the available files for 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.
fill_device=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.
filesize=irange
Individual file sizes. May be a range, in which case fio will select sizes for files at random within the given range, limited to size in total (if that is given). If filesize is not specified, each created file is the same size.
blocksize=int[,int], bs=int[,int]
Block size for I/O units. Default: 4k. Values for reads and writes can be specified separately in the format read,write, either of which may be empty to leave that value at its default.
blocksize_range=irange[,irange], bsrange=irange[,irange]
Specify a range of I/O block sizes. The issued I/O unit will always be a multiple of the minimum size, unless blocksize_unaligned is set. Applies to both reads and writes if only one range is given, but can be specified separately with a comma seperating the values. Example: bsrange=1k-4k,2k-8k. Also (see blocksize).
bssplit=str
This option allows even finer grained control of the block sizes issued, not just even splits between them. With this option, you can weight various block sizes for exact control of the issued IO for a job that has mixed block sizes. The format of the option is bssplit=blocksize/percentage, optionally adding as many definitions as needed seperated by a colon. Example: bssplit=4k/10:64k/50:32k/40 would issue 50% 64k blocks, 10% 4k blocks and 40% 32k blocks. bssplit also supports giving separate splits to reads and writes. The format is identical to what the bs option accepts, the read and write parts are separated with a comma.
blocksize_unaligned, bs_unaligned
If set, any size in blocksize_range may be used. This typically won't work with direct I/O, as that normally requires sector alignment.
blockalign=int[,int], ba=int[,int]
At what boundary to align random IO offsets. Defaults to the same as 'blocksize' the minimum blocksize given. Minimum alignment is typically 512b for using direct IO, though it usually depends on the hardware block size. This option is mutually exclusive with using a random map for files, so it will turn off that option.
zero_buffers
Initialise buffers with all zeros. Default: fill buffers with random data.
refill_buffers
If this option is given, fio will refill the IO buffers on every submit. The default is to only fill it at init time and reuse that data. Only makes sense if zero_buffers isn't specified, naturally. If data verification is enabled, refill_buffers is also automatically enabled.
nrfiles=int
Number of files to use for this job. Default: 1.
openfiles=int
Number of files to keep open at the same time. Default: nrfiles.
file_service_type=str
Defines how files to service are selected. The following types are defined:
random
Choose a file at random
roundrobin
Round robin over open files (default). sequential Do each file in the set sequentially.
The number of I/Os to issue before switching a new file can be specified by appending `:int' to the service type.
ioengine=str
Defines how the job issues I/O. The following types are defined:
sync
Basic read(2) or write(2) I/O. fseek(2) is used to position the I/O location.
psync
Basic pread(2) or pwrite(2) I/O.
vsync
Basic readv(2) or writev(2) I/O. Will emulate queuing by coalescing adjacents IOs into a single submission.
libaio
Linux native asynchronous I/O.
posixaio
glibc POSIX asynchronous I/O using aio_read(3) and aio_write(3).
mmap
File is memory mapped with mmap(2) and data copied using memcpy(3).
splice
splice(2) is used to transfer the data and vmsplice(2) to transfer data from user-space to the kernel.
syslet-rw
Use the syslet system calls to make regular read/write asynchronous.
sg
SCSI generic sg v3 I/O. May be either synchronous using the SG_IO ioctl, or if the target is an sg character device, we use read(2) and write(2) for asynchronous I/O.
null
Doesn't transfer any data, just pretends to. Mainly used to exercise fio itself and for debugging and testing purposes.
net
Transfer over the network. filename must be set appropriately to `host/port' regardless of data direction. If receiving, only the port argument is used.
netsplice
Like net, but uses splice(2) and vmsplice(2) to map data and send/receive.
cpuio
Doesn't transfer any data, but burns CPU cycles according to cpuload and cpucycles parameters.
guasi
The GUASI I/O engine is the Generic Userspace Asynchronous Syscall Interface approach to asycnronous I/O.
See <http://www.xmailserver.org/guasi-lib.html>.
external
Loads an external I/O engine object file. Append the engine filename as `:enginepath'.
iodepth=int
Number of I/O units to keep in flight against the file. Default: 1.
iodepth_batch=int
Number of I/Os to submit at once. Default: iodepth.
iodepth_batch_complete=int
This defines how many pieces of IO to retrieve at once. It defaults to 1 which
 means that we'll ask for a minimum of 1 IO in the retrieval process from the kernel. The IO retrieval will go on until we hit the limit set by iodepth_low. If this variable is set to 0, then fio will always check for completed events before queuing more IO. This helps reduce IO latency, at the cost of more retrieval system calls.
iodepth_low=int
Low watermark indicating when to start filling the queue again. Default: iodepth.
direct=bool
If true, use non-buffered I/O (usually O_DIRECT). Default: false.
buffered=bool
If true, use buffered I/O. This is the opposite of the direct parameter. Default: true.
offset=int
Offset in the file to start I/O. Data before the offset will not be touched.
fsync=int
How many I/Os to perform before issuing an fsync(2) of dirty data. If 0, don't sync. Default: 0.
fdatasync=int
Like fsync, but uses fdatasync(2) instead to only sync the data parts of the file. Default: 0.
sync_file_range=str:int
Use sync_file_range() for every val number of write operations. Fio will track range of writes that have happened since the last sync_file_range() call. str can currently be one or more of:
wait_before
SYNC_FILE_RANGE_WAIT_BEFORE
write
SYNC_FILE_RANGE_WRITE
wait_after
SYNC_FILE_RANGE_WRITE
So if you do sync_file_range=wait_before,write:8, fio would use SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE for every 8 writes. Also see the sync_file_range(2) man page. This option is Linux specific.
overwrite=bool
If writing, setup the file first and do overwrites. Default: false.
end_fsync=bool
Sync file contents when job exits. Default: false.
fsync_on_close=bool
If true, sync file contents on close. This differs from end_fsync in that it will happen on every close, not just at the end of the job. Default: false.
rwmixcycle=int
How many milliseconds before switching between reads and writes for a mixed workload. Default: 500ms.
rwmixread=int
Percentage of a mixed workload that should be reads. Default: 50.
rwmixwrite=int
Percentage of a mixed workload that should be writes. If rwmixread and rwmixwrite are given and do not sum to 100%, the latter of the two overrides the first. This may interfere with a given rate setting, if fio is asked to limit reads or writes to a certain rate. If that is the case, then the distribution may be skewed. Default: 50.
norandommap
Normally fio will cover every block of the file when doing random I/O. If this parameter is given, a new offset will be chosen without looking at past I/O history. This parameter is mutually exclusive with verify.
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 disabled by default.
nice=int
Run job with given nice value. See nice(2).
prio=int
Set I/O priority value of this job between 0 (highest) and 7 (lowest). See ionice(1).
prioclass=int
Set I/O priority class. See ionice(1).
thinktime=int
Stall job for given number of microseconds between issuing I/Os.
thinktime_spin=int
Pretend to spend CPU time for given number of microseconds, sleeping the rest of the time specified by thinktime. Only valid if thinktime is set.
thinktime_blocks=int
Number of blocks to issue before waiting thinktime microseconds. Default: 1.
rate=int
Cap bandwidth used by this job. The number is in bytes/sec, the normal postfix rules apply. You can use rate=500k to limit reads and writes to 500k each, or you can specify read and writes separately. Using rate=1m,500k would limit reads to 1MB/sec and writes to 500KB/sec. Capping only reads or writes can be done with rate=,500k or rate=500k,. The former will only limit writes (to 500KB/sec), the latter will only limit reads.
ratemin=int
Tell fio to do whatever it can to maintain at least the given bandwidth. Failing to meet this requirement will cause the job to exit. The same format as rate is used for read vs write separation.
rate_iops=int
Cap the bandwidth to this number of IOPS. Basically the same as rate, just specified independently of bandwidth. The same format as rate is used for read vs write seperation. If blocksize is a range, the smallest block size is used as the metric.
rate_iops_min=int
If this rate of I/O is not met, the job will exit. The same format as rate is used for read vs write seperation.
ratecycle=int
Average bandwidth for rate and ratemin over this number of milliseconds. Default: 1000ms.
cpumask=int
Set CPU affinity for this job. int is a bitmask of allowed CPUs the job may run on. See sched_setaffinity(2).
cpus_allowed=str
Same as cpumask, but allows a comma-delimited list of CPU numbers.
startdelay=int
Delay start of job for the specified number of seconds.
runtime=int
Terminate processing after the specified number of seconds.
time_based
If given, run for the specified runtime duration even if the files are completely read or written. The same workload will be repeated as many times as runtime allows.
ramp_time=int
If set, fio will run the specified workload for this amount of time before logging any performance numbers. Useful for letting performance settle before logging results, thus minimizing the runtime required for stable results. Note that the ramp_time is considered lead in time for a job, thus it will increase the total runtime if a special timeout or runtime is specified.
invalidate=bool
Invalidate buffer-cache for the file prior to starting I/O. Default: true.
sync=bool
Use synchronous I/O for buffered writes. For the majority of I/O engines, this means using O_SYNC. Default: false.
iomem=str, mem=str
Allocation method for I/O unit buffer. Allowed values are:
malloc
Allocate memory with malloc(3).
shm
Use shared memory buffers allocated through shmget(2).
shmhuge
Same as shm, but use huge pages as backing.
mmap
Use mmap(2) for allocation. Uses anonymous memory unless a filename is given after the option in the format `:file'.
mmaphuge
Same as mmap, but use huge files as backing.
The amount of memory allocated is the maximum allowed blocksize for the job multiplied by iodepth. For shmhuge or mmaphuge to work, the system must have free huge pages allocated. mmaphuge also needs to have hugetlbfs mounted, and file must point there. At least on Linux, huge pages must be manually allocated. See /proc/sys/vm/nr_hugehages and the documentation for that. Normally you just need to echo an appropriate number, eg echoing 8 will ensure that the OS has 8 huge pages ready for use.
iomem_align=int
This indiciates the memory alignment of the IO memory buffers. Note that the given alignment is applied to the first IO unit buffer, if using iodepth the alignment of the following buffers are given by the bs used. In other words, if using a bs that is a multiple of the page sized in the system, all buffers will be aligned to this value. If using a bs that is not page aligned, the alignment of subsequent IO memory buffers is the sum of the iomem_align and bs used.
hugepage-size=int
Defines the size of a huge page. Must be at least equal to the system setting. Should be a multiple of 1MB. Default: 4MB.
exitall
Terminate all jobs when one finishes. Default: wait for each job to finish.
bwavgtime=int
Average bandwidth calculations over the given time in milliseconds. Default: 500ms.
create_serialize=bool
If true, serialize file creation for the jobs. Default: true.
create_fsync=bool
fsync(2) data file after creation. Default: true.
create_on_open=bool
If true, the files are not created until they are opened for IO by the job.
pre_read=bool
If this is given, files will be pre-read into memory before starting the given IO operation. This will also clear the invalidate flag, since it is pointless to pre-read and then drop the cache. This will only work for IO engines that are seekable, since they allow you to read the same data multiple times. Thus it will not work on eg network or splice IO.
unlink=bool
Unlink job files when done. Default: false.
loops=int
Specifies the number of iterations (runs of the same workload) of this job. Default: 1.
do_verify=bool
Run the verify phase after a write phase. Only valid if verify is set. Default: true.
verify=str
Method of verifying file contents after each iteration of the job. Allowed values are:
md5 crc16 crc32 crc32c crc32c-intel crc64 crc7 sha256 sha512 sha1
Store appropriate checksum in the header of each block. crc32c-intel is hardware accelerated SSE4.2 driven, falls back to regular crc32c if not supported by the system.
meta
Write extra information about each I/O (timestamp, block number, etc.). The block number is verified. See verify_pattern as well.
null
Pretend to verify. Used for testing internals.

This option can be used for repeated burn-in tests of a system to make sure that the written data is also correctly read back. If the data direction given is a read or random read, fio will assume that it should verify a previously written file. If the data direction includes any form of write, the verify will be of the newly written data.

verify_sort=bool
If true, written verify blocks are sorted if fio deems it to be faster to read them back in a sorted manner. Default: true.
verify_offset=int
Swap the verification header with data somewhere else in the block before writing. It is swapped back before verifying.
verify_interval=int
Write the verification header for this number of bytes, which should divide blocksize. Default: blocksize.
verify_pattern=str
If set, fio will fill the io buffers with this pattern. Fio defaults to filling with totally random bytes, but sometimes it's interesting to fill with a known pattern for io verification purposes. Depending on the width of the pattern, fio will fill 1/2/3/4 bytes of the buffer at the time(it can be either a decimal or a hex number). The verify_pattern if larger than a 32-bit quantity has to be a hex number that starts with either "0x" or "0X". Use with verify=meta.
verify_fatal=bool
If true, exit the job on the first observed verification failure. Default: false.
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, causing fio to offload the duty of verifying IO contents to one or more separate threads. If using this offload option, even sync IO engines can benefit from using an iodepth setting higher than 1, as it allows them to have IO in flight while verifies are running.
verify_async_cpus=str
Tell fio to set the given CPU affinity on the async IO verification threads. See cpus_allowed for the format used.
verify_backlog=int
Fio will normally verify the written contents of a job that utilizes verify once that job has completed. In other words, everything is written then everything is read back and verified. You may want to verify continually instead for a variety of reasons. Fio stores the meta data 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 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).
stonewall
Wait for preceeding jobs in the job file to exit before starting this one. stonewall implies new_group.
new_group
Start a new reporting group. If not given, all jobs in a file will be part of the same reporting group, unless separated by a stonewall.
numjobs=int
Number of clones (processes/threads performing the same workload) of this job. Default: 1.
group_reporting
If set, display per-group reports instead of per-job when numjobs is specified.
thread
Use threads created with pthread_create(3) instead of processes created with fork(2).
zonesize=int
Divide file into zones of the specified size in bytes. See zoneskip.
zoneskip=int
Skip the specified number of bytes when zonesize bytes of data have been read.
write_iolog=str
Write the issued I/O patterns to the specified file.
read_iolog=str
Replay the I/O patterns contained in the specified file generated by write_iolog, or may be a blktrace binary file.
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 jobs in their lifetime. The included fio_generate_plots script uses gnuplot to turn these text files into nice graphs. See write_log_log for behaviour of given filename. For this option, the postfix is _bw.log.
write_lat_log
Same as write_bw_log, but writes I/O completion latencies. If no filename is given with this option, the default filename of "jobname_type.log" is used. Even if the filename is given, fio will still append the type of log.
disable_lat =bool
Disable measurements of total latency numbers. Useful only for cutting back the number of calls to gettimeofday, as that does impact performance at really high IOPS rates. Note that to really get rid of a large amount of these calls, this option must be used with disable_slat and disable_bw as well.
disable_clat =bool
Disable measurements of submission latency numbers. See disable_lat.
disable_slat =bool
Disable measurements of submission latency numbers. See disable_lat.
disable_bw_measurement =bool
Disable measurements of throughput/bandwidth numbers. See disable_lat.
lockmem=int
Pin the specified amount of memory with mlock(2). Can be used to simulate a smaller amount of memory.
exec_prerun=str
Before running the job, execute the specified command with system(3).
exec_postrun=str
Same as exec_prerun, but the command is executed after the job completes.
ioscheduler=str
Attempt to switch the device hosting the file to the specified I/O scheduler.
cpuload=int
If the job is a CPU cycle-eater, attempt to use the specified percentage of CPU cycles.
cpuchunks=int
If the job is a CPU cycle-eater, split the load into cycles of the given time in milliseconds.
disk_util=bool
Generate disk utilization statistics if the platform supports it. Default: true.
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 the gettimeofday() call count. With this option enabled, we only do about 0.4% of the gtod() calls we would have done if all time keeping was enabled.
gtod_cpu=int
Sometimes it's cheaper to dedicate a single thread of execution to just getting the current time. Fio (and databases, for instance) are very intensive on gettimeofday() calls. With this option, you can set one CPU aside for doing nothing but logging current time to a shared memory location. Then the other threads/processes that run IO workloads need only copy that segment, instead of entering the kernel with a gettimeofday() call. The CPU set aside for doing these time calls will be excluded from other uses. Fio will manually clear it from the CPU mask of other jobs.
cgroup=str
Add job to this control group. If it doesn't exist, it will be created. The system must have a mounted cgroup blkio mount point for this to work. If your system doesn't have it mounted, you can do so with:

# mount -t cgroup -o blkio none /cgroup

cgroup_weight=int
Set the weight of the cgroup to this value. See the documentation that comes with the kernel, allowed values are in the range of 100..1000.
cgroup_nodelete=bool
Normally fio will delete the cgroups it has created after the job completion. To override this behavior and to leave cgroups around after the job completion, set cgroup_nodelete=1. This can be useful if one wants to inspect various cgroup files after job completion. Default: false
uid=int
Instead of running as the invoking user, set the user ID to this value before the thread/process does any work.
gid=int
Set group ID, see uid.

OUTPUT

While running, fio will display the status of the created jobs. For example:
Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s]
The characters in the first set of brackets denote the current status of each threads. The possible values are:
P
Setup but not started.
C
Thread created.
I
Initialized, waiting.
R
Running, doing sequential reads.
r
Running, doing random reads.
W
Running, doing sequential writes.
w
Running, doing random writes.
M
Running, doing mixed sequential reads/writes.
m
Running, doing mixed random reads/writes.
F
Running, currently waiting for fsync(2).
V
Running, verifying written data.
E
Exited, not reaped by main thread.
-
Exited, thread reaped.
The second set of brackets shows the estimated completion percentage of the current group. The third set shows the read and write I/O rate, respectively. Finally, the estimated run time of the job is displayed. When fio completes (or is interrupted by Ctrl-C), it will show data for each thread, each group of threads, and each disk, in that order. Per-thread statistics first show the threads client number, group-id, and error code. The remaining figures are as follows:
io
Number of megabytes of I/O performed.
bw
Average data rate (bandwidth).
runt
Threads run time.
slat
Submission latency minimum, maximum, average and standard deviation. This is the time it took to submit the I/O.
clat
Completion latency minimum, maximum, average and standard deviation. This is the time between submission and completion.
bw
Bandwidth minimum, maximum, percentage of aggregate bandwidth received, average and standard deviation.
cpu
CPU usage statistics. Includes user and system time, number of context switches this thread went through and number of major and minor page faults.
IO depths
Distribution of I/O depths. Each depth includes everything less than (or equal) to it, but greater than the previous depth.
IO issued
Number of read/write requests issued, and number of short read/write requests.
IO latencies
Distribution of I/O completion latencies. The numbers follow the same pattern as IO depths.
The group statistics show:
io
Number of megabytes I/O performed.
aggrb
Aggregate bandwidth of threads in the group.
minb
Minimum average bandwidth a thread saw.
maxb
Maximum average bandwidth a thread saw.
mint
Shortest runtime of threads in the group.
maxt
Longest runtime of threads in the group.
Finally, disk statistics are printed with reads first:
ios
Number of I/Os performed by all groups.
merge
Number of merges in the I/O scheduler.
ticks
Number of ticks we kept the disk busy.
io_queue
Total time spent in the disk queue.
util
Disk utilization.

TERSE OUTPUT

If the --minimal option is given, the results will be printed in a semicolon-delimited format suitable for scripted use. The fields are:
jobname, groupid, error Read status:
KB I/O, bandwidth (KB/s), runtime (ms) Submission latency:
min, max, mean, standard deviation
Completion latency:
min, max, mean, standard deviation
Bandwidth:
min, max, aggregate percentage of total, mean, standard deviation
Write status:
KB I/O, bandwidth (KB/s), runtime (ms) Submission latency:
min, max, mean, standard deviation
Completion latency:
min, max, mean, standard deviation
Bandwidth:
min, max, aggregate percentage of total, mean, standard deviation
CPU usage:
user, system, context switches, major page faults, minor page faults
IO depth distribution:
<=1, 2, 4, 8, 16, 32, >=64
IO latency distribution (ms):
<=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, >=2000
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AUTHORS

fio was written by Jens Axboe <jens.axboe@oracle.com>, now Jens Axboe <jaxboe@fusionio.com>.
This man page was written by Aaron Carroll <aaronc@cse.unsw.edu.au> based on documentation by Jens Axboe.

REPORTING BUGS

Report bugs to the fio mailing list <fio@vger.kernel.org>. See README.

SEE ALSO

For further documentation see HOWTO and README.
Sample jobfiles are available in the examples directory.