Ubuntu Manpage: lvreduce - Reduce the size of a logical volume

Provided by: lvm2_2.02.176-4.1ubuntu3.18.04.3_amd64

NAME

       lvreduce - Reduce the size of a logical volume

SYNOPSIS

       lvreduce option_args position_args
           [ option_args ]

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  lvconvert(8) to change the number of data images in a RAID or
       mirrored LV.

       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 before running lvreduce so that the removed
       extents are not in use by the file system.

       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.

       In  the  usage section below, --size Size can be replaced with --extents Number.  See both
       descriptions the options section.

USAGE

       lvreduce -L|--size [-]Size[m|UNIT] LV
           [ -l|--extents [-]Number[PERCENT] ]
           [ -A|--autobackup y|n ]
           [ -f|--force ]
           [ -n|--nofsck ]
           [ -r|--resizefs ]
           [    --noudevsync ]
           [    --reportformat basic|json ]
           [ COMMON_OPTIONS ]

       Common options for lvm:
           [ -d|--debug ]
           [ -h|--help ]
           [ -q|--quiet ]
           [ -t|--test ]
           [ -v|--verbose ]
           [ -y|--yes ]
           [    --commandprofile String ]
           [    --config String ]
           [    --driverloaded y|n ]
           [    --longhelp ]
           [    --profile String ]
           [    --version ]

OPTIONS

-A|--autobackup y|n
Specifies if metadata should be backed up automatically after a change. Enabling
this is strongly advised! See vgcfgbackup(8) for more information.

--commandprofile String
The command profile to use for command configuration. See lvm.conf(5) for more
information about profiles.

--config String
Config settings for the command. These override lvm.conf settings. The String arg
uses the same format as lvm.conf, or may use section/field syntax. See lvm.conf(5)
for more information about config.

-d|--debug ...
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).

--driverloaded y|n
If set to no, the command will not attempt to use device-mapper. For testing and
debugging.

-l|--extents [-]Number[PERCENT]
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 %VG denotes the total size of
the VG, the suffix %FREE the remaining free space in the VG, and the suffix %PVS
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 %ORIGIN (100%ORIGIN
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 + or minus - prefix is used, the value is not an absolute
size, but is relative and added or subtracted from the current size.

-f|--force ...
Override various checks, confirmations and protections. Use with extreme caution.

-h|--help
Display help text.

--longhelp
Display long help text.

-n|--nofsck
Do not perform fsck before resizing filesystem when filesystem requires it. You may
need to use --force to proceed with this option.

--noudevsync
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.

--profile String
An alias for --commandprofile or --metadataprofile, depending on the command.

-q|--quiet ...
Suppress output and log messages. Overrides --debug and --verbose. Repeat once to
also suppress any prompts with answer 'no'.

--reportformat basic|json
Overrides current output format for reports which is defined globally by the
report/output_format setting in lvm.conf. basic 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. json produces report output in
JSON format. See lvmreport(7) for more information.

-r|--resizefs
Resize underlying filesystem together with the LV using fsadm(8).

-L|--size [-]Size[m|UNIT]
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 + or minus -
prefix is used, the value is not an absolute size, but is relative and added or
subtracted from the current size.

-t|--test
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.

-v|--verbose ...
Set verbose level. Repeat from 1 to 4 times to increase the detail of messages sent
to stdout and stderr.

--version
Display version information.

-y|--yes
Do not prompt for confirmation interactively but always assume the answer yes. Use
with extreme caution. (For automatic no, see -qq.)

VARIABLES

       LV
              Logical Volume name.  See lvm(8) for valid names.  An LV positional  arg  generally
              includes the VG name and LV name, e.g. VG/LV.

       String
              See the option description for information about the string content.

       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: bBsSkKmMgGtTpPeE.  b|B is bytes, s|S is
              sectors  of 512 bytes, k|K is kilobytes, m|M is megabytes, g|G is gigabytes, t|T is
              terabytes, p|P is petabytes, e|E is exabytes.  (This should not  be  confused  with
              the output control --units, where capital letters mean multiple of 1000.)

ENVIRONMENT VARIABLES

       See  lvm(8)  for  information  about  environment  variables  used  by  lvm.  For example,
       LVM_VG_NAME can generally be substituted for a required VG parameter.

EXAMPLES

       Reduce the size of an LV by 3 logical extents:
       lvreduce -l -3 vg00/lvol1