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       fio - flexible I/O tester


       fio [options] [jobfile]...


       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


              Write output to filename.

              Limit run time to timeout seconds.

              Generate per-job latency logs.

              Generate per-job bandwidth logs.

              Print statistics in a terse, semicolon-delimited format.

              Convert jobfile to a set of command-line options.

              Enable read-only safety checks.

              Specifies when real-time ETA estimate should be  printed.   when
              may be one of ‘always’, ‘never’ or ‘auto’.

              Only run section sec from job file.

              Print  help  information  for  command.   May  be  ‘all’ for all

              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

       --help Display usage information and exit.

              Display version information and exit.


       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

   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.


       Some  parameters may take arguments of a specific type.  The types used

       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).

       bool   Boolean:  a  true or false value. ‘0’ denotes false, ‘1’ denotes

       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:

   Parameter List
              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.

              Human-readable description of the job. It is  printed  when  the
              job is run, but otherwise has no special purpose.

              Prefix  filenames with this directory.  Used to place files in a
              location other than ‘./’.

              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.

              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.

                             Only one thread or process may do IO at the time,
                             excluding all others.

                             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.

                             Random reads.

                             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.

              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.

              Seed the random number generator in a predictable way so results
              are repeatable across runs.  Default: true.

              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

              Disable  use  of  posix_fadvise(2) to advise the kernel what I/O
              patterns are likely to be issued. Default: true.

              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.

              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.

              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  seperately 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 seperately with  a
              comma seperating the values. Example: bsrange=1k-4k,2k-8k.  Also
              (see blocksize).

              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

       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

       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.

              Initialise  buffers  with  all zeros. Default: fill buffers with
              random data.

              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.

              Number of files to use for this job.  Default: 1.

              Number of files  to  keep  open  at  the  same  time.   Default:

              Defines  how files to service are selected.  The following types
              are defined:

                      random Choose a file at random

                             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.

              Defines  how  the  job  issues  I/O.   The  following  types are

                      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

                      libaio Linux native asynchronous I/O.

                             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.

                             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.

                             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  <>.

                             Loads an external I/O engine object file.  Append
                             the engine filename as ‘:enginepath’.

              Number of  I/O  units  to  keep  in  flight  against  the  file.
              Default: 1.

              Number of I/Os to submit at once.  Default: iodepth.

              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.

              Low  watermark indicating when to start filling the queue again.
              Default: iodepth.

              If true, use  non-buffered  I/O  (usually  O_DIRECT).   Default:

              If  true,  use buffered I/O.  This is the opposite of the direct
              parameter.  Default: true.

              Offset in the file to start I/O. Data before the offset will not
              be touched.

              How  many  I/Os  to  perform before issuing an fsync(2) of dirty
              data.  If 0, don’t sync.  Default: 0.

              Like fsync, but uses fdatasync(2) instead to only sync the  data
              parts of the file. Default: 0.

              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:


              write  SYNC_FILE_RANGE_WRITE


              So  if  you  do  sync_file_range=wait_before,write:8, fio
              would use
              writes.  Also see the sync_file_range(2) man page.  This  option
              is Linux specific.

              If  writing,  setup  the file first and do overwrites.  Default:

              Sync file contents when job exits.  Default: false.

              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.

              How many milliseconds before switching between reads and  writes
              for a mixed workload. Default: 500ms.

              Percentage  of  a  mixed workload that should be reads. Default:

              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.

              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.

              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

              Run job with given nice value.  See nice(2).

              Set I/O priority value of this job between  0  (highest)  and  7
              (lowest).  See ionice(1).

              Set I/O priority class.  See ionice(1).

              Stall job for given number of microseconds between issuing I/Os.

              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.

              Number of blocks to issue before waiting thinktime microseconds.
              Default: 1.

              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.

              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

              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.

              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.

              Average bandwidth for rate  and  ratemin  over  this  number  of
              milliseconds.  Default: 1000ms.

              Set  CPU affinity for this job. int is a bitmask of allowed CPUs
              the job may run on.  See sched_setaffinity(2).

              Same as cpumask,  but  allows  a  comma-delimited  list  of  CPU

              Delay start of job for the specified number of seconds.

              Terminate processing after the specified number of seconds.

              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.

              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 buffer-cache for the  file  prior  to  starting  I/O.
              Default: true.

              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

                             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’.

                             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.

              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.

              Defines  the size of a huge page.  Must be at least equal to the
              system setting.  Should be a multiple of 1MB. Default: 4MB.

              Terminate all jobs when one finishes.  Default:  wait  for  each
              job to finish.

              Average   bandwidth   calculations   over   the  given  time  in
              milliseconds.  Default: 500ms.

              If true, serialize file creation for the jobs.  Default: true.

              fsync(2) data file after creation.  Default: true.

              If true, the files are not created until they are opened for  IO
              by the job.

              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 job files when done.  Default: false.

              Specifies the number of iterations (runs of the  same  workload)
              of this job.  Default: 1.

              Run  the verify phase after a write phase.  Only valid if verify
              is set.  Default: true.

              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

                      meta   Write   extra   information   about   each    I/O
                             (timestamp, block number, etc.). The block number
                             is verified.

                             Fill I/O buffers with a specific pattern that  is
                             used  to  verify.  If the pattern is < 4bytes, it
                             can either be a decimal or a hexadecimal  number.
                             If  the  pattern  is  > 4bytes, currently, it can
                             only  be  a  hexadecimal  pattern  starting  with
                             either "0x" or "0X".

                      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.

              If true, written verify blocks are sorted if fio deems it to  be
              faster to read them back in a sorted manner.  Default: true.

              Swap  the  verification  header  with data somewhere else in the
              block before writing.  It is swapped back before verifying.

              Write the verification header for this number  of  bytes,  which
              should divide blocksize.  Default: blocksize.

              If  true,  exit  the  job  on  the  first  observed verification
              failure.  Default: false.

              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

              Tell  fio  to  set  the  given  CPU  affinity  on  the  async IO
              verification threads.  See cpus_allowed for the format used.

              Wait for preceeding jobs in the job file to exit before starting
              this one.  stonewall implies 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

              Number   of   clones   (processes/threads  performing  the  same
              workload) of this job.  Default: 1.

              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).

              Divide file into zones of the  specified  size  in  bytes.   See

              Skip  the  specified number of bytes when zonesize bytes of data
              have been read.

              Write the issued I/O patterns to the specified file.

              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

              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_clat =bool
              Disable  measurements of completion 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_slat =bool
              Disable   measurements   of   submission  latency  numbers.  See

       disable_bw_measurement =bool
              Disable  measurements  of  throughput/bandwidth   numbers.   See

              Pin  the  specified amount of memory with mlock(2).  Can be used
              to simulate a smaller amount of memory.

              Before running the  job,  execute  the  specified  command  with

              Same  as  exec_prerun, but the command is executed after the job

              Attempt to switch the device hosting the file to  the  specified
              I/O scheduler.

              If  the  job  is a CPU cycle-eater, attempt to use the specified
              percentage of CPU cycles.

              If the job is a CPU cycle-eater, split the load into  cycles  of
              the given time in milliseconds.

              Generate  disk  utilization  statistics if the platform supports
              it. Default: true.

              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.

              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.

              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

              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.

              Instead of running as the invoking user, set the user ID to this
              value before the thread/process does any work.

              Set group ID, see uid.


       While  running,  fio  will display the status of the created jobs.  For

              Threads:  1:  [_r]  [24.8%  done]  [  13509/   8334  kb/s]  [eta

       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

              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.
                     Total time spent in the disk queue.
              util   Disk utilization.


       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
                             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
                             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

              text description


       fio was written by Jens Axboe <>.
       This  man  page  was  written by Aaron Carroll <>
       based on documentation by Jens Axboe.


       Report bugs to the fio mailing list <>.  See README.


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