NAME

     zhack — libzpool debugging tool

DESCRIPTION

     This utility pokes configuration changes directly into a ZFS pool, which is dangerous and
     can cause data corruption.

SYNOPSIS

      zhack       feature stat       pool
             List feature flags.

      zhack feature enable [-d description] [-r] pool guid
             Add a new feature to pool that is uniquely identified by guid, which is specified in
             the same form as a zfs(8) user property.

             The description is a short human readable explanation of the new feature.

             The -r flag indicates that pool can be safely opened in read-only mode by a system
             that does not understand the guid feature.

      zhack feature ref [-d|-m] pool guid
             Increment the reference count of the guid feature in pool.

             The -d flag decrements the reference count of the guid feature in pool instead.

             The -m flag indicates that the guid feature is now required to read the pool MOS.

GLOBAL OPTIONS

     The following can be passed to all zhack invocations before any subcommand:

     -c cachefile
             Read pool configuration from the cachefile, which is /etc/zfs/zpool.cache by
             default.

     -d dir  Search for pool members in dir.  Can be specified more than once.

EXAMPLES

     # zhack feature stat tank
     for_read_obj:
             org.illumos:lz4_compress = 0
     for_write_obj:
             com.delphix:async_destroy = 0
             com.delphix:empty_bpobj = 0
     descriptions_obj:
             com.delphix:async_destroy = Destroy filesystems asynchronously.
             com.delphix:empty_bpobj = Snapshots use less space.
             org.illumos:lz4_compress = LZ4 compression algorithm support.

     # zhack feature enable -d 'Predict future disk failures.' tank com.example:clairvoyance
     # zhack feature ref tank com.example:clairvoyance

SEE ALSO

     ztest(1), zpool-features(7), zfs(8)