NAME

     ztest — was written by the ZFS Developers as a ZFS unit test

SYNOPSIS

     ztest [-VEG] [-v vdevs] [-s size_of_each_vdev] [-a alignment_shift] [-m mirror_copies]
           [-r raidz_disks/draid_disks] [-R raid_parity] [-K raid_kind] [-D draid_data]
           [-S draid_spares] [-C vdev_class_state] [-d datasets] [-t threads]
           [-g gang_block_threshold] [-i initialize_pool_i_times] [-k kill_percentage]
           [-p pool_name] [-T time] [-z zil_failure_rate]

DESCRIPTION

     ztest was written by the ZFS Developers as a ZFS unit test.  The tool was developed in
     tandem with the ZFS functionality and was executed nightly as one of the many regression
     test against the daily build.  As features were added to ZFS, unit tests were also added to
     ztest.  In addition, a separate test development team wrote and executed more functional and
     stress tests.

     By default ztest runs for ten minutes and uses block files (stored in /tmp) to create pools
     rather than using physical disks.  Block files afford ztest its flexibility to play around
     with zpool components without requiring large hardware configurations.  However, storing the
     block files in /tmp may not work for you if you have a small tmp directory.

     By default is non-verbose.  This is why entering the command above will result in ztest
     quietly executing for 5 minutes.  The -V option can be used to increase the verbosity of the
     tool.  Adding multiple -V options is allowed and the more you add the more chatty ztest
     becomes.

     After the ztest run completes, you should notice many ztest.* files lying around.  Once the
     run completes you can safely remove these files.  Note that you shouldn't remove these files
     during a run.  You can re-use these files in your next ztest run by using the -E option.

OPTIONS

     -h, -?, --help
           Print a help summary.

     -v, --vdevs= (default: 5)
           Number of vdevs.

     -s, --vdev-size= (default: 64M)
           Size of each vdev.

     -a, --alignment-shift= (default: 9) (use 0 for random)
           Alignment shift used in test.

     -m, --mirror-copies= (default: 2)
           Number of mirror copies.

     -r, --raid-disks= (default: 4 for raidz/16 for draid)
           Number of raidz/draid disks.

     -R, --raid-parity= (default: 1)
           Raid parity (raidz & draid).

     -K, --raid-kind=raidz|draid|random (default: random)
           The kind of RAID config to use.  With random the kind alternates between raidz and
           draid.

     -D, --draid-data= (default: 4)
           Number of data disks in a dRAID redundancy group.

     -S, --draid-spares= (default: 1)
           Number of dRAID distributed spare disks.

     -d, --datasets= (default: 7)
           Number of datasets.

     -t, --threads= (default: 23)
           Number of threads.

     -g, --gang-block-threshold= (default: 32K)
           Gang block threshold.

     -i, --init-count= (default: 1)
           Number of pool initializations.

     -k, --kill-percentage= (default: 70%)
           Kill percentage.

     -p, --pool-name= (default: ztest)
           Pool name.

     -f, --vdev-file-directory= (default: /tmp)
           File directory for vdev files.

     -M, --multi-host
           Multi-host; simulate pool imported on remote host.

     -E, --use-existing-pool
           Use existing pool (use existing pool instead of creating new one).

     -T, --run-time= (default: 300s)
           Total test run time.

     -P, --pass-time= (default: 60s)
           Time per pass.

     -F, --freeze-loops= (default: 50)
           Max loops in spa_freeze().

     -B, --alt-ztest=
           Alternate ztest path.

     -C, --vdev-class-state=on|off|random (default: random)
           The vdev allocation class state.

     -o, --option=variable=value
           Set global variable to an unsigned 32-bit integer value (little-endian only).

     -G, --dump-debug
           Dump zfs_dbgmsg buffer before exiting due to an error.

     -V, --verbose
           Verbose (use multiple times for ever more verbosity).

EXAMPLES

     To override /tmp as your location for block files, you can use the -f option:
           # ztest -f /

     To get an idea of what ztest is actually testing try this:
           # ztest -f / -VVV

     Maybe you'd like to run ztest for longer? To do so simply use the -T option and specify the
     runlength in seconds like so:
           # ztest -f / -V -T 120

ENVIRONMENT VARIABLES

     ZFS_HOSTID=id
         Use id instead of the SPL hostid to identify this host.  Intended for use with ztest,
         but this environment variable will affect any utility which uses libzpool, including
         zpool(8).  Since the kernel is unaware of this setting, results with utilities other
         than ztest are undefined.

     ZFS_STACK_SIZE=stacksize
         Limit the default stack size to stacksize bytes for the purpose of detecting and
         debugging kernel stack overflows.  This value defaults to 32K which is double the
         default 16K Linux kernel stack size.

         In practice, setting the stack size slightly higher is needed because differences in
         stack usage between kernel and user space can lead to spurious stack overflows
         (especially when debugging is enabled).  The specified value will be rounded up to a
         floor of PTHREAD_STACK_MIN which is the minimum stack required for a NULL procedure in
         user space.

         By default the stack size is limited to 256K.

SEE ALSO

     zdb(1), zfs(1), zpool(1), spl(4)