.TH LVREDUCE 8 "LVM TOOLS #VERSION#" "Red Hat, Inc."
.
.SH NAME
.
lvreduce \(em Reduce the size of a logical volume
.
.SH SYNOPSIS
.
\fBlvreduce\fP \fIoption_args\fP \fIposition_args\fP
.br
    [ \fIoption_args\fP ]
.br
.
.SH DESCRIPTION
.
lvreduce reduces the size of an LV. The freed logical extents are returned
to the VG to be used by other LVs. A copy-on-write snapshot LV can also
be reduced if less space is needed to hold COW blocks. Use
\fBlvconvert\fP(8) to change the number of data images in a RAID or
mirrored LV.
.P
Be careful when reducing an LV's size, because data in the reduced area is
lost. Ensure that any file system on the LV is resized \fBbefore\fP
running lvreduce so that the removed extents are not in use by the file
system.
.P
Sizes will be rounded if necessary. For example, the LV size must be an
exact number of extents, and the size of a striped segment must be a
multiple of the number of stripes.
.P
In the usage section below, \fB--size\fP \fISize\fP can be replaced
with \fB--extents\fP \fINumber\fP.  See both descriptions
the options section.
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.SH USAGE
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\fBlvreduce\fP \fB-L\fP|\fB--size\fP [\fB-\fP]\fISize\fP[m|UNIT] \fILV\fP
.br
.RS 4
.ad l
[ \fB-l\fP|\fB--extents\fP [\fB-\fP]\fINumber\fP[PERCENT] ]
.br
[ \fB-A\fP|\fB--autobackup\fP \fBy\fP|\fBn\fP ]
.br
[ \fB-f\fP|\fB--force\fP ]
.br
[ \fB-n\fP|\fB--nofsck\fP ]
.br
[ \fB-r\fP|\fB--resizefs\fP ]
.br
[    \fB--noudevsync\fP ]
.br
[    \fB--reportformat\fP \fBbasic\fP|\fBjson\fP ]
.br
[ COMMON_OPTIONS ]
.ad b
.RE
.P
Common options for lvm:
.
.RS 4
.ad l
[ \fB-d\fP|\fB--debug\fP ]
.br
[ \fB-h\fP|\fB--help\fP ]
.br
[ \fB-q\fP|\fB--quiet\fP ]
.br
[ \fB-t\fP|\fB--test\fP ]
.br
[ \fB-v\fP|\fB--verbose\fP ]
.br
[ \fB-y\fP|\fB--yes\fP ]
.br
[    \fB--commandprofile\fP \fIString\fP ]
.br
[    \fB--config\fP \fIString\fP ]
.br
[    \fB--devices\fP \fIPV\fP ]
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[    \fB--devicesfile\fP \fIString\fP ]
.br
[    \fB--driverloaded\fP \fBy\fP|\fBn\fP ]
.br
[    \fB--lockopt\fP \fIString\fP ]
.br
[    \fB--longhelp\fP ]
.br
[    \fB--nolocking\fP ]
.br
[    \fB--profile\fP \fIString\fP ]
.br
[    \fB--version\fP ]
.ad b
.RE
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.SH OPTIONS
.
.
.HP
\fB-A\fP|\fB--autobackup\fP \fBy\fP|\fBn\fP
.br
Specifies if metadata should be backed up automatically after a change.
Enabling this is strongly advised! See \fBvgcfgbackup\fP(8) for more information.
.
.HP
\fB--commandprofile\fP \fIString\fP
.br
The command profile to use for command configuration.
See \fBlvm.conf\fP(5) for more information about profiles.
.
.HP
\fB--config\fP \fIString\fP
.br
Config settings for the command. These override \fBlvm.conf\fP(5) settings.
The String arg uses the same format as \fBlvm.conf\fP(5),
or may use section/field syntax.
See \fBlvm.conf\fP(5) for more information about config.
.
.HP
\fB-d\fP|\fB--debug\fP ...
.br
Set debug level. Repeat from 1 to 6 times to increase the detail of
messages sent to the log file and/or syslog (if configured).
.
.HP
\fB--devices\fP \fIPV\fP
.br
Devices that the command can use. This option can be repeated
or accepts a comma separated list of devices. This overrides
the devices file.
.
.HP
\fB--devicesfile\fP \fIString\fP
.br
A file listing devices that LVM should use.
The file must exist in \fI#DEFAULT_SYS_DIR#/devices/\fP and is managed
with the \fBlvmdevices\fP(8) command.
This overrides the \fBlvm.conf\fP(5) \fBdevices/devicesfile\fP and
\fBdevices/use_devicesfile\fP settings.
.
.HP
\fB--driverloaded\fP \fBy\fP|\fBn\fP
.br
If set to no, the command will not attempt to use device-mapper.
For testing and debugging.
.
.HP
\fB-l\fP|\fB--extents\fP [\fB-\fP]\fINumber\fP[PERCENT]
.br
Specifies the new size of the LV in logical extents.
The --size and --extents options are alternate methods of specifying size.
The total number of physical extents used will be
greater when redundant data is needed for RAID levels.
An alternate syntax allows the size to be determined indirectly
as a percentage of the size of a related VG, LV, or set of PVs. The
suffix \fB%VG\fP denotes the total size of the VG, the suffix \fB%FREE\fP
the remaining free space in the VG, and the suffix \fB%PVS\fP the free
space in the specified PVs.  For a snapshot, the size
can be expressed as a percentage of the total size of the origin LV
with the suffix \fB%ORIGIN\fP (\fB100%ORIGIN\fP provides space for
the whole origin).
When expressed as a percentage, the size defines an upper limit for the
number of logical extents in the new LV. The precise number of logical
extents in the new LV is not determined until the command has completed.
When the plus \fB+\fP or minus \fB-\fP prefix is used,
the value is not an absolute size, but is relative and added or subtracted
from the current size.
.
.HP
\fB-f\fP|\fB--force\fP ...
.br
Override various checks, confirmations and protections.
Use with extreme caution.
.
.HP
\fB-h\fP|\fB--help\fP
.br
Display help text.
.
.HP
\fB--lockopt\fP \fIString\fP
.br
Used to pass options for special cases to lvmlockd.
See \fBlvmlockd\fP(8) for more information.
.
.HP
\fB--longhelp\fP
.br
Display long help text.
.
.HP
\fB-n\fP|\fB--nofsck\fP
.br
Do not perform fsck before resizing filesystem when filesystem
requires it. You may need to use --force to proceed with
this option.
.
.HP
\fB--nolocking\fP
.br
Disable locking.
.
.HP
\fB--noudevsync\fP
.br
Disables udev synchronisation. The process will not wait for notification
from udev. It will continue irrespective of any possible udev processing
in the background. Only use this if udev is not running or has rules that
ignore the devices LVM creates.
.
.HP
\fB--profile\fP \fIString\fP
.br
An alias for --commandprofile or --metadataprofile, depending
on the command.
.
.HP
\fB-q\fP|\fB--quiet\fP ...
.br
Suppress output and log messages. Overrides --debug and --verbose.
Repeat once to also suppress any prompts with answer 'no'.
.
.HP
\fB--reportformat\fP \fBbasic\fP|\fBjson\fP
.br
Overrides current output format for reports which is defined globally by
the report/output_format setting in \fBlvm.conf\fP(5).
\fBbasic\fP is the original format with columns and rows.
If there is more than one report per command, each report is prefixed
with the report name for identification. \fBjson\fP produces report
output in JSON format. See \fBlvmreport\fP(7) for more information.
.
.HP
\fB-r\fP|\fB--resizefs\fP
.br
Resize underlying filesystem together with the LV using fsadm(8).
.
.HP
\fB-L\fP|\fB--size\fP [\fB-\fP]\fISize\fP[m|UNIT]
.br
Specifies the new size of the LV.
The --size and --extents options are alternate methods of specifying size.
The total number of physical extents used will be
greater when redundant data is needed for RAID levels.
When the plus \fB+\fP or minus \fB-\fP prefix is used,
the value is not an absolute size, but is relative and added or subtracted
from the current size.
.
.HP
\fB-t\fP|\fB--test\fP
.br
Run in test mode. Commands will not update metadata.
This is implemented by disabling all metadata writing but nevertheless
returning success to the calling function. This may lead to unusual
error messages in multi-stage operations if a tool relies on reading
back metadata it believes has changed but hasn't.
.
.HP
\fB-v\fP|\fB--verbose\fP ...
.br
Set verbose level. Repeat from 1 to 4 times to increase the detail
of messages sent to stdout and stderr.
.
.HP
\fB--version\fP
.br
Display version information.
.
.HP
\fB-y\fP|\fB--yes\fP
.br
Do not prompt for confirmation interactively but always assume the
answer yes. Use with extreme caution.
(For automatic no, see -qq.)
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.SH VARIABLES
.
.TP
.I LV
Logical Volume name.  See \fBlvm\fP(8) for valid names.
An LV positional arg generally includes the VG name and LV name, e.g. VG/LV.
.TP
.I String
See the option description for information about the string content.
.TP
.IR Size [UNIT]
Size is an input number that accepts an optional unit.
Input units are always treated as base two values, regardless of
capitalization, e.g. 'k' and 'K' both refer to 1024.
The default input unit is specified by letter, followed by |UNIT.
UNIT represents other possible input units:
.BR b | B
is bytes,
.BR s | S
is sectors of 512 bytes,
.BR k | K
is KiB,
.BR m | M
is MiB,
.BR g | G
is GiB,
.BR t | T
is TiB,
.BR p | P
is PiB,
.BR e | E
is EiB.
(This should not be confused with the output control --units, where
capital letters mean multiple of 1000.)
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.SH ENVIRONMENT VARIABLES
.
See \fBlvm\fP(8) for information about environment variables used by lvm.
For example, LVM_VG_NAME can generally be substituted for a required VG parameter.