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

Provided by: lvm2_2.03.07-1ubuntu1_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 ]
           [    --lockopt String ]
           [    --longhelp ]
           [    --nolocking ]
           [    --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.

--lockopt String
Used to pass options for special cases to lvmlockd. See lvmlockd(8) for more information.

--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.

--nolocking
Disable locking.

--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