c7996ddf80
The gunion(8) utility is used to track changes to a read-only disk on a writable disk. Logically, a writable disk is placed over a read-only disk. Write requests are intercepted and stored on the writable disk. Read requests are first checked to see if they have been written on the top (writable disk) and if found are returned. If they have not been written on the top disk, then they are read from the lower disk. The gunion(8) utility can be especially useful if you have a large disk with a corrupted filesystem that you are unsure of how to repair. You can use gunion(8) to place another disk over the corrupted disk and then attempt to repair the filesystem. If the repair fails, you can revert all the changes in the upper disk and be back to the unchanged state of the lower disk thus allowing you to try another approach to repairing it. If the repair is successful you can commit all the writes recorded on the top disk to the lower disk. Another use of the gunion(8) utility is to try out upgrades to your system. Place the upper disk over the disk holding your filesystem that is to be upgraded and then run the upgrade on it. If it works, commit it; if it fails, revert the upgrade. Further details can be found in the gunion(8) manual page. Reviewed by: Chuck Silvers, kib (earlier version) tested by: Peter Holm Differential Revision: https://reviews.freebsd.org/D32697
224 lines
5.3 KiB
Groff
224 lines
5.3 KiB
Groff
.\" Copyright (c) 2004-2005 Pawel Jakub Dawidek <pjd@FreeBSD.org>
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd January 19, 2022
|
|
.Dt GEOM 8
|
|
.Os
|
|
.Sh NAME
|
|
.Nm geom
|
|
.Nd "universal control utility for GEOM classes"
|
|
.Sh SYNOPSIS
|
|
.Nm
|
|
.Ar class
|
|
.Cm help
|
|
.Nm
|
|
.Ar class
|
|
.Cm list
|
|
.Op Fl a
|
|
.Op Ar name ...
|
|
.Nm
|
|
.Ar class
|
|
.Cm status
|
|
.Op Fl ags
|
|
.Op Ar name ...
|
|
.Nm
|
|
.Ar class
|
|
.Cm load
|
|
.Op Fl v
|
|
.Nm
|
|
.Ar class
|
|
.Cm unload
|
|
.Op Fl v
|
|
.Nm
|
|
.Fl p
|
|
.Ar provider-name
|
|
.Nm
|
|
.Fl t
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
utility is used to control various GEOM classes.
|
|
A class has to be aware of
|
|
.Xr geom 8
|
|
communication methods, but there are also some standard commands
|
|
which can be used for existing
|
|
.Xr geom 8
|
|
unaware classes.
|
|
Here is the list of standard commands:
|
|
.Bl -tag -width ".Cm status"
|
|
.It Cm help
|
|
List all available commands for the given class.
|
|
.It Cm list
|
|
Print detailed information (within the given class) about all geoms
|
|
(if no additional arguments were specified) or the given geoms.
|
|
This command is only available if the given class exists in the kernel.
|
|
Additional options include:
|
|
.Bl -tag -width ".Fl a"
|
|
.It Fl a
|
|
Print information for geoms without providers.
|
|
.El
|
|
.It Cm status
|
|
Print general information (within the given class) about all geoms
|
|
(if no additional arguments were specified) or the given geoms.
|
|
This command is only available if the given class exists in the kernel.
|
|
.Pp
|
|
Additional options include:
|
|
.Bl -tag -width ".Fl s"
|
|
.It Fl a
|
|
When used with -g, print status for geoms without providers.
|
|
.It Fl g
|
|
Report statuses for geoms instead of providers.
|
|
.It Fl s
|
|
Produce script-friendly output.
|
|
.El
|
|
.It Cm load
|
|
Load the kernel module that implements the given class.
|
|
This command is only available if the class does not yet exist in the kernel and
|
|
the file
|
|
.Pa geom_ Ns Ao Ar class Ac Ns Pa .ko
|
|
can be found in one of the directories specified in
|
|
.Va kern.module_path
|
|
sysctl.
|
|
.It Cm unload
|
|
Unload the kernel module which implements the given class.
|
|
This command is only available if the given class is loaded as a
|
|
kernel module.
|
|
.El
|
|
.Pp
|
|
Additional options include:
|
|
.Bl -tag -width ".Cm status"
|
|
.It Fl p Ar provider-name
|
|
Print detailed information about the geom which provides
|
|
.Ar provider-name .
|
|
.It Fl t
|
|
Display geoms hierarchy as a tree.
|
|
.El
|
|
.Pp
|
|
Class-specific commands are implemented as shared libraries which
|
|
are stored in
|
|
.Pa /lib/geom/
|
|
directory and are loaded via
|
|
.Xr dlopen 3
|
|
function when the class name is known.
|
|
When a class-specific shared library exists, a direct utility should also be
|
|
available under the name of
|
|
.Nm g Ns Ar class .
|
|
.Pp
|
|
Currently available classes which are aware of
|
|
.Xr geom 8 :
|
|
.Pp
|
|
.Bl -bullet -offset indent -compact
|
|
.It
|
|
CACHE
|
|
.It
|
|
CONCAT
|
|
.It
|
|
ELI
|
|
.It
|
|
JOURNAL
|
|
.It
|
|
LABEL
|
|
.It
|
|
MIRROR
|
|
.It
|
|
MOUNTVER
|
|
.It
|
|
MULTIPATH
|
|
.It
|
|
NOP
|
|
.It
|
|
PART
|
|
.It
|
|
RAID
|
|
.It
|
|
RAID3
|
|
.It
|
|
SCHED
|
|
.It
|
|
SHSEC
|
|
.It
|
|
STRIPE
|
|
.It
|
|
UNION
|
|
.It
|
|
VIRSTOR
|
|
.El
|
|
.Sh ENVIRONMENT
|
|
The following environment variables affect the execution of
|
|
.Nm :
|
|
.Bl -tag -width ".Ev GEOM_LIBRARY_PATH"
|
|
.It Ev GEOM_LIBRARY_PATH
|
|
Specifies the path where shared libraries are stored instead of
|
|
.Pa /lib/geom/ .
|
|
Multiple paths can be specified with a colon-separated list of paths.
|
|
.El
|
|
.Sh EXIT STATUS
|
|
Exit status is 0 on success, and 1 if the command fails.
|
|
.Sh EXAMPLES
|
|
The following example shows how to set up a stripe on three disks for automatic
|
|
configuration:
|
|
.Bd -literal -offset indent
|
|
geom stripe label -v -s 65536 data /dev/da0 /dev/da1 /dev/da2
|
|
or:
|
|
gstripe label -v -s 65536 data /dev/da0 /dev/da1 /dev/da2
|
|
.Ed
|
|
.Pp
|
|
Print the list of all providers from the DISK class:
|
|
.Bd -literal -offset indent
|
|
geom disk list
|
|
.Ed
|
|
.Pp
|
|
Unload a kernel module which implements the MD class:
|
|
.Bd -literal -offset indent
|
|
geom md unload
|
|
.Ed
|
|
.Sh SEE ALSO
|
|
.Xr libgeom 3 ,
|
|
.Xr geom 4 ,
|
|
.Xr gcache 8 ,
|
|
.Xr gconcat 8 ,
|
|
.Xr geli 8 ,
|
|
.Xr gjournal 8 ,
|
|
.Xr glabel 8 ,
|
|
.Xr gmirror 8 ,
|
|
.Xr gmountver 8 ,
|
|
.Xr gmultipath 8 ,
|
|
.Xr gnop 8 ,
|
|
.Xr gpart 8 ,
|
|
.Xr graid3 8 ,
|
|
.Xr gsched 8 ,
|
|
.Xr gshsec 8 ,
|
|
.Xr gstripe 8 ,
|
|
.Xr gunion 8 ,
|
|
.Xr gvirstor 8
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
utility appeared in
|
|
.Fx 5.3 .
|
|
.Sh AUTHORS
|
|
.An Pawel Jakub Dawidek Aq Mt pjd@FreeBSD.org
|