ZHACK(1) General Commands Manual ZHACK(1)
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.
zhack label repair [−cu] device
Repair labels of a specified device according to options.
Flags may be combined to do their functions simultaneously.
The −c flag repairs corrupted label checksums
The −u flag restores the label on a detached device
Example:
zhack label repair −cu device
Fix checksums and undetach a device
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) OpenZFS May 26, 2021 ZHACK(1)