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 vgreduce(1M)							vgreduce(1M)




 NAME
      vgreduce - remove physical volumes from an LVM volume group

 SYNOPSIS
      /usr/sbin/vgreduce [-A autobackup] vg_name pv_path ...

      /usr/sbin/vgreduce [-A autobackup] [-l] vg_name pv_path

      /usr/sbin/vgreduce [-A autobackup] [-f] vg_name

    Remarks
      vgreduce cannot be performed if the volume group is activated in shared
      mode.

 DESCRIPTION
      The vgreduce command removes each physical volume specified by a
      pv_path argument from volume group vg_name.

      The vgreduce command with -f option removes all missing physical
      volume from the volume group.

      All but one physical volume can be removed.  The last physical volume
      must remain in the volume group so that the logical volume driver can
      continue to operate.  The last physical volume in the volume group can
      be removed with the vgremove command (see vgremove(1M)).

      Before executing vgreduce, remove all logical volumes residing on each
      physical volume represented by a pv_path by executing lvremove (see
      lvremove(1M)).

      Any physical volume in the pv_path list that is also a member of a
      physical volume group (as defined in /etc/lvmpvg) is also removed from
      the physical volume group.  If the physical volume happens to be the
      last one in the physical volume group, the physical volume group is
      also removed from the volume group.

      When a physical volume in the pv_path list has multiple PV-links, the
      physical volume is not removed from the volume group, until all the
      links to the volume are removed.	When a physical volume in the
      pv_path list is the primary link (in use) to a physical volume,
      removing the link forces LVM to switch to the alternate link to access
      the physical volume.  When the pv_path removed is an alternate link to
      the device, only the link is removed; the volume group and physical
      volume are otherwise unchanged.

    Options and Arguments
      vgreduce recognizes the following options and arguments:

	   -A autobackup  Set automatic backup for this invocation of this
			  command.  autobackup can have one of the following
			  values:



 Hewlett-Packard Company	    - 1 -   HP-UX Release 11i: November 2000






 vgreduce(1M)							vgreduce(1M)




			  y    Automatically back up configuration changes
			       made to the volume group.  This is the
			       default.

			       After this command executes, the vgcfgbackup
			       command (see vgcfgbackup(1M)) is executed for
			       the volume group.

			  n    Do not back up configuration changes this
			       time.

	   -f vg_name	  force reduction of missing physical volume(s) in a
			  given volume group.  This option does not require
			  a physical volume (PV) to be supplied on the
			  command line.	 vgreduce obtains the name of each
			  physical volume (PV) belonging to the volume group
			  from the file /etc/lvmtab.  It then reads the LVM
			  structures from each PV and compares these with
			  that held by the kernel to work out which PVs are
			  missing. PVs which are missing will be candidates
			  for removal. If all the physical extents on the
			  missing PV are free then it will be removed from
			  the volume group. Otherwise vgreduce will report
			  the physical to logical extent mapping.  For
			  missing PVs, which have extents in use, you must
			  free up all the extents by using lvreduce(1M) or
			  lvremove(1M) and re-run vgreduce with the -f
			  option.  This option is most commonly used when
			  the vgdisplay(1M) command shows "Cur PV" higher
			  than "Act PV" and all of the PVs belonging to the
			  volume group are attached.  This option only works
			  on PVs and not on links.

	   -l pv_path	  This option removes the specified pv_path/s from
			  the lvmtab file.  This task will only be performed
			  if the pv_path is currently marked as missing from
			  the volume group.  This option was mainly designed
			  for the problem where the vgscan or the vgimport
			  command place too many links beyond the max limit
			  allowed in the lvmtab file.  Currently the max
			  limit is 8 paths to a PV (7 alternates and one
			  primary).  In this situation invoking the command
			  without the -f option will not resolve the
			  condition because the path is not attached to the
			  volume group.	 Similarly the condition would not
			  be overcome by invoking with the -f option as this
			  works on PVs rather than links.

	   pv_path	  The block device path name of a physical volume.





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 vgreduce(1M)							vgreduce(1M)




	   vg_name	  The path name of the volume group.

 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
      Remove physical volume /dev/dsk/c0t1d0 from volume group /dev/vg01:

	   vgreduce /dev/vg01 /dev/dsk/c0t1d0

      Force reduction of missing PVs from volume group: vg01

	   vgreduce -f /dev/vg01

      Removes the physical volume from the volume group when it is still in
      the lvmtab file, but it is currently marked as missing from the volume
      group: vg01

	   vgreduce -l /dev/vg01

      The following messages will appear after missing PVS has been removed
      successfully:

		PV with key 0 successfully deleted from vg /dev/vg01

		Repair done, please do the following steps.....:

		1.  Save /etc/lvmtab to another file.

		2.  Remove /etc/lvmtab.

		3.  Use vgscan -v to recreate /etc/lvmtab.

		4.  NOW use vgcfgbackup(1M) to save the LVM setup.

 SEE ALSO
      vgchange(1M), vgcreate(1M), vgdisplay(1M), vgextend(1M).











 Hewlett-Packard Company	    - 3 -   HP-UX Release 11i: November 2000