lvreduce(1M)lvreduce(1M)NAMElvreduce - decrease space allocation or the number of mirror copies of
logical volumes
SYNOPSIS
autobackup] le_number lv_path
autobackup] lv_size lv_path
autobackup] mirror_copies lv_path [pv_path ...]
autobackup] mirror_copies lv_path pvkey ...
Remarks
Mirrored disk operations require the installation of the optional HP
MirrorDisk/UX software, which is not included in the standard HP-UX
operating system.
DESCRIPTION
The command reduces the number of logical extents allocated to a logi‐
cal volume specified by lv_path. The excess physical extents in the
logical volume and any mirror copies are deallocated.
Alternatively, it reduces the number of mirror copies in the logical
volume. The physical extents that comprise the deleted mirror copy or
copies are deallocated. If pv_path ... is specified, the mirror or
mirrors to be removed will be deallocated from those specific physical
volumes.
asks for confirmation before deallocating logical extents if the option
is omitted.
Options and Arguments
The option and pv_path argument are only meaningful if the optional HP
MirrorDisk/UX software has been installed on the system.
recognizes the following options and arguments:
lv_path The block device path name of a logical vol‐
ume.
pv_path The block device path name of a physical
volume.
Set automatic backup for invocation of this command.
autobackup can have one of the following
values:
Automatically back up configuration changes
made to the logical volume.
This is the default.
After this command executes, the com‐
mand (see vgcfgbackup(1M)) is exe‐
cuted for the volume group to which
the logical volume belongs.
Do not back up configuration changes.
Force reduction of the number of logical extents
without first requesting confirmation.
This option can be dangerous when there is a
file system on the lv_path that is larger
than the size that the logical volume is
being reduced to. If the file system is
unmounted, the option forces the reduction
of the logical volume without reducing the
file system. The file system becomes cor‐
rupt and is not mountable. If the file sys‐
tem is mounted, fails, preventing a mounted
file system from becoming corrupted.
Decrease the space allocated to the logical volume,
specified in logical extents. le_number is
a decimal value smaller than the current
number of logical extents.
le_number must be at least 1 and no greater
than a volume group version-dependent maxi‐
mum; use the command to determine the maxi‐
mum number of logical extents for the volume
group version.
One, and only one, or option must be sup‐
plied.
Decrease the space allocated to the logical volume,
specified in megabytes. lv_size is a deci‐
mal value smaller than the current logical
volume size.
lv_size must be at least 1 and no greater
than a volume group version-dependent maxi‐
mum; use the command to determine the maxi‐
mum size for the volume group version.
lv_size is rounded up to the nearest multi‐
ple of the logical extent size, equivalent
to the physical extent size defined for the
volume group by the command (see vgcre‐
ate(1M)).
One, and only one, or option must be speci‐
fied.
Reduce the number of mirror copies allocated for each logical
extent.
A mirror copy contains the same data as the
original. mirror_copies must be at least 0
and smaller than the volume group version-
dependent maximum; use the command to deter‐
mine the maximum number of mirror copies for
the volume group version. mirror_copies
must be smaller than the current value.
If optional pv_path arguments are specified,
the mirror copies are deallocated from the
specified physical volumes.
One, and only one, or option must be speci‐
fied.
This option should be used only in the special instance when you
want to reduce a mirrored logical volume on
a physical volume that is missing or has
failed. Use to obtain the pvkey (Physical
Volume Number in VG).
Use this option with the option.
Shared Volume Group Considerations
For volume group version 1.0 and 2.0, cannot be used if the volume
group is activated in shared mode. For volume groups version 2.1 (or
higher), can be performed when activated in either shared, exclusive,
or standalone mode.
Note that the daemon must be running on all the nodes sharing a volume
group activated in shared mode. See lvmpud(1M).
LVM shared mode is currently only available in Serviceguard clusters.
EXTERNAL INFLUENCES
Environment Variables
determines the language in which messages are displayed.
If is not specified or is null, it defaults to "C" (see lang(5)).
If any internationalization variable contains an invalid setting, all
internationalization variables default to "C" (see environ(5)).
EXAMPLES
Decrease the number of the logical extents of a logical volume to one
hundred:
Reduce to one mirror (that is, an original and one copy) for each logi‐
cal extent of a logical volume:
Remove mirror copies of logical extents of a logical volume from the
physical volume
Remove a logical volume from a one-way mirrored set on the specified
pvkeys:
WARNINGS
LVM does not store any information about which physical extents within
a logical volume contain useful data; therefore, reducing the space
allocated to a logical volume without doing a prior backup of the data
could lead to the loss of useful data. The command on a logical volume
containing a file system of greater length than the size being reduced
to will cause data corruption.
To reduce a logical volume being used for swap, that swap area must not
be currently in use.
SEE ALSOlvcreate(1M), lvdisplay(1M), lvextend(1M), lvmadm(1M), lvmpud(1M),
pvchange(1M), pvdisplay(1M), intro(7), lvm(7).
lvreduce(1M)
