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.\"
.\" CDDL HEADER START
.\"
.\" The contents of this file are subject to the terms of the
.\" Common Development and Distribution License (the "License").
.\" You may not use this file except in compliance with the License.
.\"
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
.\" or http://www.opensolaris.org/os/licensing.
.\" See the License for the specific language governing permissions
.\" and limitations under the License.
.\"
.\" When distributing Covered Code, include this CDDL HEADER in each
.\" file and include the License file at usr/src/OPENSOLARIS.LICENSE.
.\" If applicable, add the following below this CDDL HEADER, with the
.\" fields enclosed by brackets "[]" replaced with your own identifying
.\" information: Portions Copyright [yyyy] [name of copyright owner]
.\"
.\" CDDL HEADER END
.\"
.\" Copyright 2013 Darik Horn <dajhorn@vanadac.com>. All rights reserved.
.\"
.\" lint-ok: WARNING: sections out of conventional order: Sh SYNOPSIS
.\"
.Dd May 26, 2021
.Dt ZHACK 1
.Os
.
.Sh NAME
.Nm zhack
.Nd libzpool debugging tool
.Sh DESCRIPTION
This utility pokes configuration changes directly into a ZFS pool,
which is dangerous and can cause data corruption.
.Sh SYNOPSIS
.Bl -tag -width Ds
.It Xo
.Nm zhack
.Cm feature stat
.Ar pool
.Xc
List feature flags.
.
.It Xo
.Nm zhack
.Cm feature enable
.Op Fl d Ar description
.Op Fl r
.Ar pool
.Ar guid
.Xc
Add a new feature to
.Ar pool
that is uniquely identified by
.Ar guid ,
which is specified in the same form as a
.Xr zfs 8
user property.
.Pp
The
.Ar description
is a short human readable explanation of the new feature.
.Pp
The
.Fl r
flag indicates that
.Ar pool
can be safely opened in read-only mode by a system that does not understand the
.Ar guid
feature.
.
.It Xo
.Nm zhack
.Cm feature ref
.Op Fl d Ns | Ns Fl m
.Ar pool
.Ar guid
.Xc
Increment the reference count of the
.Ar guid
feature in
.Ar pool .
.Pp
The
.Fl d
flag decrements the reference count of the
.Ar guid
feature in
.Ar pool
instead.
.Pp
The
.Fl m
flag indicates that the
.Ar guid
feature is now required to read the pool MOS.
.El
.
.Sh GLOBAL OPTIONS
The following can be passed to all
.Nm
invocations before any subcommand:
.Bl -tag -width "-d dir"
.It Fl c Ar cachefile
Read
.Ar pool
configuration from the
.Ar cachefile ,
which is
.Pa /etc/zfs/zpool.cache
by default.
.It Fl d Ar dir
Search for
.Ar pool
members in
.Ar dir .
Can be specified more than once.
.El
.
.Sh EXAMPLES
.Bd -literal
# 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
.Ed
.
.Sh SEE ALSO
.Xr ztest 1 ,
.Xr zpool-features 7 ,
.Xr zfs 8
|
