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 lvreduce(1M)							lvreduce(1M)




 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

    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 argument 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:



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 lvreduce(1M)							lvreduce(1M)




			       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.





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 lvreduce(1M)							lvreduce(1M)




	   -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.

			       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 specified
      pv_path.

	   lvreduce -m 0 -k /dev/vg01/lvol1 /dev/dsk/c1t0d0





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 lvreduce(1M)							lvreduce(1M)




 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.

 SEE ALSO
      lvcreate(1M), lvdisplay(1M), lvextend(1M), pvchange(1M),
      pvdisplay(1M).








































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