lvreduce(1M)															      lvreduce(1M)

NAME

       lvreduce - 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 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.

       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 volume.

	      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 command (see vgcfgbackup(1M)) is executed 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 corrupt and is not mountable.  If  the
				  file system 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 maximum; use the command to
				  determine the maximum number of logical extents for the volume group version.

				  One, and only one, or option must be supplied.

	      Decrease the space allocated to the logical volume,
				  specified in megabytes.  lv_size is a decimal value smaller than the current logical volume size.

				  lv_size must be at least 1 and no greater than a volume group version-dependent  maximum;  use  the  command	to
				  determine the maximum size for the volume group version.

				  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 command (see vgcreate(1M)).

				  One, and only one, or option must be specified.

	      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 determine 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  vol-
				  umes.

				  One, and only one, or option must be specified.

	      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 logical 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 ALSO

       lvcreate(1M), lvdisplay(1M), lvextend(1M), lvmadm(1M), lvmpud(1M), pvchange(1M), pvdisplay(1M), intro(7), lvm(7).

																      lvreduce(1M)