This section describes in details each parameter associated with a job.
Some parameters take an option of a given type, such as an integer or
-a string. The following types are used:
+a string. Anywhere a numeric value is required, an arithmetic expression
+may be used, provided it is surrounded by parentheses. Supported operators
+are:
+
+ addition (+)
+ subtraction (-)
+ multiplication (*)
+ division (/)
+ modulus (%)
+ exponentiation (^)
+
+For time values in expressions, units are microseconds by default. This is
+different than for time values not in expressions (not enclosed in
+parentheses). The following types are used:
str String. This is a sequence of alpha characters.
time Integer with possible time suffix. In seconds unless otherwise
randread Random reads
rw,readwrite Sequential mixed reads and writes
randrw Random mixed reads and writes
+ trimwrite Mixed trims and writes. Blocks will be
+ trimmed first, then written to.
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,
randrepeat=bool For random IO workloads, seed the generator in a predictable
way so that results are repeatable across repetitions.
+ Defaults to true.
randseed=int Seed the random number generators based on this seed value, to
be able to control what sequence of output is being generated.
If not set, the random sequence depends on the randrepeat
setting.
-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:
If set, fio will use POSIX_FADV_SEQUENTIAL for sequential
IO and POSIX_FADV_RANDOM for random IO.
+fadvise_stream=int Notify the kernel what write stream ID to place these
+ writes under. Only supported on Linux. Note, this option
+ may change going forward.
+
size=int The total size of file io for this job. Fio will run until
this many bytes has been transferred, unless runtime is
- 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. If not set, fio will use the full
- size of the given files or devices. If 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.
-
+ limited by other options (such as 'runtime', for instance,
+ or increased/decreased by 'io_size'). Unless specific nrfiles
+ and filesize options are given, fio will divide this size
+ between the available files specified by the job. If not set,
+ fio will use the full size of the given files or devices.
+ If 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.
+
+io_size=int
io_limit=int Normally fio operates within the region set by 'size', which
means that the 'size' option sets both the region and size of
IO to be performed. Sometimes that is not what you want. With
this option, it is possible to define just the amount of IO
that fio should do. For instance, if 'size' is set to 20G and
- 'io_limit' is set to 5G, fio will perform IO within the first
- 20G but exit when 5G have been done.
+ 'io_size' is set to 5G, fio will perform IO within the first
+ 20G but exit when 5G have been done. The opposite is also
+ possible - if 'size' is set to 20G, and 'io_size' is set to
+ 40G, then fio will do 40G of IO within the 0..20G region.
filesize=int Individual file sizes. May be a range, in which case fio
will select sizes for files at random within the given range
zero_buffers If this option is given, fio will init the IO buffers to
all zeroes. The default is to fill them with random data.
- The resulting IO buffers will not be completely zeroed,
- unless scramble_buffers is also turned off.
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
buffer_compress_percentage=int If this is set, then fio will attempt to
provide IO buffer content (on WRITEs) that compress to
the specified level. Fio does this by providing a mix of
- random data and zeroes. Note that this is per block size
- unit, for file/disk wide compression level that matches
- this setting, you'll also want to set refill_buffers.
+ random data and a fixed pattern. The fixed pattern is either
+ zeroes, or the pattern specified by buffer_pattern. If the
+ pattern option is used, it might skew the compression ratio
+ slightly. Note that this is per block size unit, for file/disk
+ wide compression level that matches this setting, you'll also
+ want to set refill_buffers.
buffer_compress_chunk=int See buffer_compress_percentage. This
setting allows fio to manage how big the ranges of random
necessary environment variables to work with
hdfs/libhdfs properly.
+ mtd Read, write and erase an MTD character device
+ (e.g., /dev/mtd0). Discards are treated as
+ erases. Depending on the underlying device
+ type, the I/O may have to go in a certain
+ pattern, e.g., on NAND, writing sequentially
+ to erase blocks and discarding before
+ overwriting. The writetrim mode works well
+ for this constraint.
+
external Prefix to specify loading an external
IO engine object file. Append the engine
filename, eg ioengine=external:/tmp/foo.o
after fio has filled the queue of 16 requests, it will let
the depth drain down to 4 before starting to fill it again.
+io_submit_mode=str This option controls how fio submits the IO to
+ the IO engine. The default is 'inline', which means that the
+ fio job threads submit and reap IO directly. If set to
+ 'offload', the job threads will offload IO submission to a
+ dedicated pool of IO threads. This requires some coordination
+ and thus has a bit of extra overhead, especially for lower
+ queue depth IO where it can increase latencies. The benefit
+ is that fio can manage submission rates independently of
+ the device completion rates. This avoids skewed latency
+ reporting if IO gets back up on the device side (the
+ coordinated omission problem).
+
direct=bool If value is true, use non-buffered io. This is usually
O_DIRECT. Note that ZFS on Solaris doesn't support direct io.
On Windows the synchronous ioengines don't support direct io.
random IO. If this option is given, fio will just get a
new random offset without looking at past io history. This
means that some blocks may not be read or written, and that
- some blocks may be read/written more than once. This option
- is mutually exclusive with verify= if and only if multiple
- blocksizes (via bsrange=) are used, since fio only tracks
- complete rewrites of blocks.
+ some blocks may be read/written more than once. If this option
+ is used with verify= and multiple blocksizes (via bsrange=),
+ only intact blocks are verified, i.e., partially-overwritten
+ blocks are ignored.
softrandommap=bool See norandommap. If fio runs with the random block map
enabled and it fails to allocate the map, if this option is
if verify_backlog_batch is larger than verify_backlog, some
blocks will be verified more than once.
+verify_state_save=bool When a job exits during the write phase of a verify
+ workload, save its current state. This allows fio to replay
+ up until that point, if the verify state is loaded for the
+ verify read phase. The format of the filename is, roughly,
+ <type>-<jobname>-<jobindex>-verify.state. <type> is "local"
+ for a local run, "sock" for a client/server socket connection,
+ and "ip" (192.168.0.1, for instance) for a networked
+ client/server connection.
+
+verify_state_load=bool If a verify termination trigger was used, fio stores
+ the current write state of each thread. This can be used at
+ verification time so that fio knows how far it should verify.
+ Without this information, fio will run a full verification
+ pass, according to the settings in the job file used.
+
stonewall
wait_for_previous Wait for preceding jobs in the job file to exit, before
starting this one. Can be used to insert serialization
independent fio invocations. Unfortuantely this also breaks
the strict time ordering between multiple device accesses.
+replay_align=int Force alignment of IO offsets and lengths in a trace
+ to this power of 2 value.
+
+replay_scale=int Scale sector offsets down by this factor when
+ replaying traces.
+
+per_job_logs=bool If set, this generates bw/clat/iops log with per
+ file private filenames. If not set, jobs with identical names
+ will share the log filename. Default: true.
+
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
graphs. See write_lat_log for behaviour of given
filename. For this option, the suffix is _bw.x.log, where
x is the index of the job (1..N, where N is the number of
- jobs).
+ jobs). If 'per_job_logs' is false, then the filename will not
+ include the job index.
write_lat_log=str Same as write_bw_log, except that this option stores io
submission, completion, and total latencies instead. If no
The actual log names will be foo_slat.x.log, foo_clat.x.log,
and foo_lat.x.log, where x is the index of the job (1..N,
where N is the number of jobs). This helps fio_generate_plot
- fine the logs automatically.
+ fine the logs automatically. If 'per_job_logs' is false, then
+ the filename will not include the job index.
+
write_iops_log=str Same as write_bw_log, but writes IOPS. If no filename is
given with this option, the default filename of
"jobname_type.x.log" is used,where x is the index of the job
(1..N, where N is the number of jobs). Even if the filename
- is given, fio will still append the type of log.
+ is given, fio will still append the type of log. If
+ 'per_job_logs' is false, then the filename will not include
+ the job index.
log_avg_msec=int By default, fio will log an entry in the iops, latency,
or bw log for every IO that completes. When writing to the
command line parameter. The files will be stored with a
.fz suffix.
+block_error_percentiles=bool If set, record errors in trim block-sized
+ units from writes and trims and output a histogram of
+ how many trims it took to get to errors, and what kind
+ of error was encountered.
+
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.
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.
+ for completion latencies and the block error histogram.
+ 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.
clocksource=str Use the given clocksource as the base of timing. The
supported options are:
address.
[netsplice] port=int
-[net] port=int The TCP or UDP port to bind to or connect to.
+[net] port=int The TCP or UDP port to bind to or connect to. If this is used
+with numjobs to spawn multiple instances of the same job type, then this will
+be the starting port number since fio will use a range of ports.
[netsplice] interface=str
[net] interface=str The IP address of the network interface used to send or
[net] listen For TCP network connections, tell fio to listen for incoming
connections rather than initiating an outgoing connection. The
hostname must be omitted if this option is used.
+
[net] pingpong Normaly a network writer will just continue writing data, and
a network reader will just consume packages. If pingpong=1
is set, a writer will send its normal payload to the reader,
single reader when multiple readers are listening to the same
address.
+[net] window_size Set the desired socket buffer size for the connection.
+
+[net] mss Set the TCP maximum segment size (TCP_MAXSEG).
+
[e4defrag] donorname=str
File will be used as a block donor(swap extents between files)
[e4defrag] inplace=int
1 : allocate space immidietly inside defragment event,
and free right after event
+[mtd] skip_bad=bool Skip operations against known bad blocks.
6.0 Interpreting the output
bytes. The action can be one of these:
wait Wait for 'offset' microseconds. Everything below 100 is discarded.
+ The time is relative to the previous wait statement.
read Read 'length' bytes beginning from 'offset'
write Write 'length' bytes beginning from 'offset'
sync fsync() the file
and standard deviation of time to complete an unit work is reported in "unit
work" section. Options can be chosen to report detailed percpu idleness or
overall system idleness by aggregating percpu stats.
+
+
+10.0 Verification and triggers
+------------------------------
+Fio is usually run in one of two ways, when data verification is done. The
+first is a normal write job of some sort with verify enabled. When the
+write phase has completed, fio switches to reads and verifies everything
+it wrote. The second model is running just the write phase, and then later
+on running the same job (but with reads instead of writes) to repeat the
+same IO patterns and verify the contents. Both of these methods depend
+on the write phase being completed, as fio otherwise has no idea how much
+data was written.
+
+With verification triggers, fio supports dumping the current write state
+to local files. Then a subsequent read verify workload can load this state
+and know exactly where to stop. This is useful for testing cases where
+power is cut to a server in a managed fashion, for instance.
+
+A verification trigger consists of two things:
+
+1) Storing the write state of each job
+2) Executing a trigger command
+
+The write state is relatively small, on the order of hundreds of bytes
+to single kilobytes. It contains information on the number of completions
+done, the last X completions, etc.
+
+A trigger is invoked either through creation ('touch') of a specified
+file in the system, or through a timeout setting. If fio is run with
+--trigger-file=/tmp/trigger-file, then it will continually check for
+the existence of /tmp/trigger-file. When it sees this file, it will
+fire off the trigger (thus saving state, and executing the trigger
+command).
+
+For client/server runs, there's both a local and remote trigger. If
+fio is running as a server backend, it will send the job states back
+to the client for safe storage, then execute the remote trigger, if
+specified. If a local trigger is specified, the server will still send
+back the write state, but the client will then execute the trigger.
+
+10.1 Verification trigger example
+---------------------------------
+Lets say we want to run a powercut test on the remote machine 'server'.
+Our write workload is in write-test.fio. We want to cut power to 'server'
+at some point during the run, and we'll run this test from the safety
+or our local machine, 'localbox'. On the server, we'll start the fio
+backend normally:
+
+server# fio --server
+
+and on the client, we'll fire off the workload:
+
+localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger-remote="bash -c \"echo b > /proc/sysrq-triger\""
+
+We set /tmp/my-trigger as the trigger file, and we tell fio to execute
+
+echo b > /proc/sysrq-trigger
+
+on the server once it has received the trigger and sent us the write
+state. This will work, but it's not _really_ cutting power to the server,
+it's merely abruptly rebooting it. If we have a remote way of cutting
+power to the server through IPMI or similar, we could do that through
+a local trigger command instead. Lets assume we have a script that does
+IPMI reboot of a given hostname, ipmi-reboot. On localbox, we could
+then have run fio with a local trigger instead:
+
+localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger="ipmi-reboot server"
+
+For this case, fio would wait for the server to send us the write state,
+then execute 'ipmi-reboot server' when that happened.
+
+10.1 Loading verify state
+-------------------------
+To load store write state, read verification job file must contain
+the verify_state_load option. If that is set, fio will load the previously
+stored state. For a local fio run this is done by loading the files directly,
+and on a client/server run, the server backend will ask the client to send
+the files over and load them from there.
projects / fio.git / blobdiff