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ZTEST(1)                    General Commands Manual                   ZTEST(1)

NAME
     ztest - ZFS stress test utility

SYNOPSIS
     ztest [-EhV] [-a shift] [-B path] [-d datasets] [-F loops] [-f path]
           [-g threshold] [-i count] [-k percent] [-m copies] [-P passtime]
           [-p name] [-R parity] [-r disks] [-s size] [-T time] [-t threads]
           [-v vdevs]

DESCRIPTION
     The ztest utility stress tests the DMU, ZAP, SPA components of ZFS from
     user space.

     ztest provides a simple routine to test the functionality of a component
     task.  These simple routines can then be used to stress test through
     parallel execution.  Tests are run as child processes of the main
     process.

     The checksum and compression functions are changed each time a dataset is
     opened to introduce varying combinations of checksum and compression from
     block to block among objects.

     While tests are running, faults are injected into the pool to verify
     self-healing ability.

     To verify that the on-disk consistency is never lost after a crash, child
     processes are killed at random with a SIGKILL signal, after which the
     parent process invokes a new child to run the test again on the same
     storage pool.

     Many of the tests record the transaction group number as part of their
     data.  When reading old data, tests verify that the transaction group
     number is less than the current, open state, transaction group to ensure
     the consistency of tests and detect unaccounted changes.  It is advised
     that any new tests added to ztest should also perform the same check with
     transaction group numbers, if applicable.

     The main ztest process uses an mmap(2) temporary file to pass information
     to child processes which allows shared memory to survive exec(3) syscall.
     A copy of the ztest_shared_hdr_t struct containing information on the
     size and number of shared structures in the file is always stored at
     offset 0 of the file.

     For backwards compatibility testing ztest can invoke an alternative
     version of ztest after a SIGKILL signal using the -B flag.

     The following options are available:

     -a shift
            alignment shift (default: 9) use 0 for random

     -B path
            alt ztest (default: <none>) alternate ztest path

     -d datasets
            datasets (default: 7)

     -E     use existing pool instead of creating new one

     -F loops
            freezeloops (default: 50) max loops in spa_freeze()

     -f path
            dir (default: /tmp) file directory for vdev files

     -g threshold
            gang block threshold (default: 32K)

     -h     print help

     -i count
            init count (default: 1) initialize pool count times

     -k percent
            kill percentage (default: 70%)

     -m copies
            mirror copies (default: 2)

     -P passtime
            passtime (default: 60 sec) time per pass

     -p name
            pool name (default: ztest)

     -R parity
            raidz parity (default: 1)

     -r disks
            raidz disks (default: 4)

     -s size
            size of each vdev (default: 256M)

     -T time
            time (default: 300 sec) total run time

     -t threads
            threads (default: 23)

     -V     verbose (use multiple times to increase verbosity)

     -v vdevs
            number of vdevs (default: 5)

AUTHORS
     This man page was written by Sevan Janiyan <sevan@NetBSD.org>.

CAVEATS
     To allow for backward compatibility testing using older versions of ztest
     the information stored in the mmap(2) temporary file passed from parent
     process to child must remain compatible with older versions of ztest.

NetBSD 8.99.34                 December 10, 2018                NetBSD 8.99.34