NAME
lvreduce — decrease space allocation or the number of mirror copies of logical volumes
SYNOPSIS
/usr/sbin/lvreduce
[-A
autobackup]
[-f]
-l
le_number
lv_path
/usr/sbin/lvreduce
[-A
autobackup]
[-f]
-L
lv_size
lv_path
/usr/sbin/lvreduce
[-A
autobackup]
-m
mirror_copies
lv_path
[pv_path ...]
/usr/sbin/lvreduce
[-A
autobackup]
-k
-m
mirror_copies
lv_path
pv_key ...
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.
lvreduce
cannot be performed if the volume group is activated in shared mode.
DESCRIPTION
The
lvreduce
command reduces the number of logical extents
allocated to a logical 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.
lvreduce
asks for confirmation before deallocating logical extents
if the
-f
option is omitted.
Options and Arguments
The
-m
option and
pv_path
and
pv_key
arguments are only meaningful
if the optional HP MirrorDisk/UX software has been installed on the system.
lvreduce
recognizes the following options and arguments:
- lv_path
The block device path name of a logical volume.
- pv_path
The block device path name of a physical volume.
- -A autobackup
Set automatic backup for invocation of this command.
autobackup
can have one of the following values:
- y
Automatically back up configuration changes made to the logical volume.
This is the default.
After this command executes, the
vgcfgbackup
command (see
vgcfgbackup(1M))
is executed for the volume group to which the logical volume belongs.
- n
Do not back up configuration changes.
- -f
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
-f
option forces the reduction of the logical volume
without reducing the file system.
The file system becomes corrupt and is not mountable.
If the file system is mounted,
lvreduce
fails, preventing a mounted file system from becoming corrupted.
- -l le_number
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,
in the range
1
to
65535
(the implementation limit).
One, and only one,
-l,
-L,
or
-m
option must be supplied.
- -L lv_size
Decrease the space allocated to the logical volume,
specified in megabytes.
lv_size
is a decimal value smaller than the current logical volume size,
in the range
1
to
16777216
(the implementation limit).
lv_size
is rounded up to the nearest multiple of the logical extent size,
equivalent to the physical extent size defined for the volume group by the
vgcreate
command (see
vgcreate(1M)).
One, and only one,
-l,
-L,
or
-m
option must be specified.
- -m mirror_copies
Reduce the number of mirror copies allocated for each logical extent.
A mirror copy contains the same data as the original.
mirror_copies
can have the value
0
or
1.
It 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,
-l,
-L,
or
-m
option must be specified.
- -k
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. This
option will remove a mirrored logical volume from the given
pv_key
list (the Physical Volume Number in the volume group).
In order to obtain the
pv_key,
use the
-k
option in the
lvdisplay
command. See
lvdisplay(1M)
for details.
Use this option with the
-m
option.
EXTERNAL INFLUENCES
Environment Variables
LANG
determines the language in which messages are displayed.
If
LANG
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:
lvreduce -l 100 /dev/vg01/lvol3
Reduce to one mirror (that is, an original and one copy) for each logical extent
of a logical volume:
lvreduce -m 1 /dev/vg01/lvol5
Remove mirror copies of logical extents of a logical volume
from the physical volume
/dev/dsk/c1t0d0:
lvreduce -m 0 /dev/vg01/lvol4 /dev/dsk/c1t0d0
Remove a logical volume from a one-way mirrored set on
the second and third physical volumes in a volume group.
lvreduce -m 0 -k /dev/vg01/lvol1 2 3
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
lvreduce
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.