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 vgchange(1M)							vgchange(1M)




 NAME
      vgchange - set LVM volume group availability

 SYNOPSIS
    Activate volume group
      /usr/sbin/vgchange -a availability [-l] [-p] [-q quorum] [-s] [-P
      resync_daemon_count] [vg_name...]

    Assign to high availability cluster and mark volume group sharable
      /usr/sbin/vgchange -c cluster -S sharable vg_name

    Remarks
      MC/ServiceGuard cluster operations require the installation of the
      optional MC/ServiceGuard software, which is not included in the
      standard HP-UX operating system.

      Lock Manager cluster operations require the installation MC/LockManager
      software which is not included with the standard HP-UX operating
      system.

      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 vgchange command with the -a option activates or deactivates one
      or more volume groups.

      The vgchange command with the -c option controls the membership of one
      or more volume groups in a high availability cluster.  The vgchange
      command with the -c and -S options control the membership of a volume
      group and mark it sharable.

      The vgchange command without the -P resync_daemon_count option
      (default) will spawn one nomwcsyncd process for each NOMWC/NONE volume
      group being activated. This may create a lot of nomwcsyncd processes
      running concurrently when it activates a large number of NOMWC/NONE
      volume groups and overload.

      The -P resync_daemon_count option provides a way to control the number
      of concurrent nomwcsyncd processes.  The count is an advisory number
      and a different count might be chosen internally if load balance or
      other reason is needed. When specified, there are up to
      resync_daemon_count + 1 nomwcsyncd processes; one of them is the
      controlling processing to spawn others.  -P 0 will use the system
      default (currently defined to be 4).

      vg_name must be defined as a volume group in the file /etc/lvmtab.  If
      vg_name is omitted, all volume groups defined in /etc/lvmtab are
      affected.




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 vgchange(1M)							vgchange(1M)




    High Availability Cluster Overview
      Volume groups can be defined on disk volumes that are connected to two
      or more systems in a high availability cluster.  This situation has a
      high potential for data corruption unless special software is used to
      coordinate shared access to the same volume group by all systems. This
      coordination is provided by MC/ServiceGuard or MC/LockManager.

      A volume group can be marked as part of a MC/ServiceGuard cluster.
      When such a group is activated in exclusive mode, it can be accessed
      for exclusive read-write activity by only one of the systems at a
      time; the other systems can have read-only access to the data.

      A volume group can be marked as a part of an MC/LockManager cluster.
      In this case, the volume group can be marked as sharable, and may be
      activated in shared mode for read-write access by all the nodes in the
      cluster. Shared read-write access by multiple cluster nodes is
      coordinated by MC/LockManager's distributed lock manager (DLM).

    Options and Arguments
      vgchange recognizes the following options and arguments:

	   vg_name	       The path name of a volume group.

	   -a availability     Set volume group availability.  availability
			       can have one of the following values:

				    y	 Activate each specified volume
					 group and all associated physical
					 and logical volumes for read-write
					 access.  If a volume group is
					 marked as part of a high
					 availability cluster, it is
					 activated in exclusive read-write
					 mode, as for the -a e option.

				    e	 Activate each specified volume
					 group and all associated physical
					 and logical volumes for exclusive
					 read-write access.  The volume
					 group must be marked as part of a
					 high availability cluster, and the
					 availability  software must be
					 running on the system; otherwise,
					 the volume group is not activated.

				    s	 Activate each specified volume
					 group and all associated physical
					 and logical volume for shared
					 read-write access.  The volume
					 group must be marked as part of a
					 high availability cluster and



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					 marked sharable; otherwise, the
					 volume group is not activated.

					 If any of the logical volumes in
					 the volume group are mirrored, and
					 if there are more than two systems
					 in the high availability cluster,
					 this volume group will not be
					 activated because HP MirrorDisk/UX
					 software is only supported in a
					 clustered environment with a
					 maximum of two nodes configured.

				    If the -a y or -a e option is executed
				    on a currently active volume group,
				    vgchange attempts to include any
				    physical volumes that were previously
				    listed as missing.	This is useful if a
				    physical volume has come back online.
				    However, no automatic synchronization of
				    any mirrored logical volumes is done.
				    If synchronization is required, execute
				    the vgsync command (see vgsync(1M)).

				    r	 Activate each specified volume
					 group and all associated physical
					 and logical volumes for read-only
					 access.  This option is ignored for
					 a volume group that is already
					 activated.

					 If a volume group is marked as part
					 of a high availability cluster, the
					 high availability software must be
					 running on the system; otherwise,
					 the volume group is not activated.

				    n	 Deactivate each specified volume
					 group and its associated logical
					 volumes.  You must close the
					 logical volumes prior to executing
					 this option.  For example, if the
					 logical volume contains a file
					 system, the file system must be
					 unmounted.

	   -c cluster	       Control the membership of volume groups in a
			       high availability  cluster.  cluster can have
			       one of the following values:





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 vgchange(1M)							vgchange(1M)




				    y	 Mark each specified volume group as
					 a member of the high availability
					 cluster.  The high availability
					 software must be running;
					 otherwise, the volume group is not
					 marked.  Needs to be done on one
					 node only.

				    n	 Remove each specified volume group
					 from membership in the high
					 availability cluster.	The high
					 availability software does not need
					 to be running.

			       The volume group must be deactivated with the
			       -a n option before a -c y|n option can be
			       executed.

	   -S sharable	       Control the sharability of volume groups in a
			       high availability cluster.  sharable can have
			       one of the following values:

				    y	 Mark each specified volume group as
					 sharable.  The high availability
					 software must be running;
					 otherwise, the volume group is not
					 marked.  Needs to be done on one
					 node only.

				    n	 Remove the shared attribute from
					 the volume group.  The high
					 availability software does not need
					 to be running.

			       The volume group must be deactivated with the
			       -a n option before a -S y|n option can be
			       executed.

	   -l		       Disable the opening of logical volumes that
			       belong to each specified volume group.  If
			       the -l option is set, later attempts to open
			       the logical volumes will fail.  To allow an
			       opening of these logical volumes to succeed,
			       execute lvchange -a y.

	   -p		       Activate each specified volume group only if
			       all of the physical volumes that belong to it
			       are available.

	   -q quorum	       Set the quorum enforcement for each specified
			       volume group.  quorum can have one of the



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			       following values:

				    y	 Enforce the quorum requirement.
					 This is the default.

				    n	 Ignore the quorum requirement.

			       The -q n option can be used to activate the
			       volume group when the disk quorum is not
			       maintained because too many disks were lost.
			       Since it ensures the integrity of the LVM
			       configuration information, it is normally not
			       advisable to override the quorum.

	   -s		       Disable the synchronization of stale physical
			       extents within the volume group specified by
			       vg_name.	 This option is only effective when
			       used with the -a y or -a e option.

	   -P resync_daemon_count
			       gives the advisory count to control the
			       number of nomwcsyncd processes on volume
			       group activation.

    Mirrored Disk Activation
      When the optional HP MirrorDisk/UX software is running and a volume
      group is activated, LVM performs the necessary mirror consistency
      recovery for each logical volume in the volume group based on the
      state of Mirror Write Cache and Mirror Consistency Recovery (see the
      Consistency Recovery section of lvdisplay(1M)).  In a non-shared
      environment, LVM supports MWC, NOMWC and the NONE recovery.  But in
      shared environment, LVM only supports NOMWC and the NONE recovery.

	   MWC	     Recover mirror consistency by using the Mirror Write
		     Cache and Mirror Consistency Record.  This mode implies
		     that the Mirror Write Cache is on.

	   NOMWC     Recover mirror consistency by searching all logical
		     extents and copying data from a non-stale copy to the
		     other mirror copies.  This mode implies that the Mirror
		     Write Cache is off.

	   NONE	     Do not recover mirror consistency during volume group
		     activation on this logical volume.	 This mode implies
		     that the Mirror Write Cache is off.

      Next, mirror synchronization refreshes stale mirror copies by copying
      data from a nonstale copy.  If the -s option is specified on the
      command line, mirror synchronization does not occur.  However, for
      those logical volumes that have Mirror Write Cache turned off, mirror
      synchronization is done independently of whether the -s option appears



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 vgchange(1M)							vgchange(1M)




      on the command line.

    General Activation
      If vgchange cannot access a physical volume, it lists the volume's
      status as missing.  If too many physical volumes in the volume group
      are missing, vgchange reports that the group does not have a quorum
      and cannot be activated.	The lack of a quorum can be overridden with
      the -q n 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
      Activate volume group /dev/vg03:

	   vgchange -a y /dev/vg03

      Deactivate volume group /dev/vg03:

	   vgchange -a n /dev/vg03

      Activate volume group /dev/vg03 without synchronizing extents that are
      not current on logical volumes that have Mirror Write Cache turned on:

	   vgchange -a y -s /dev/vg03

    Exclusive Activation
      Set up volume group /dev/vg03 for use in a high availability cluster:

	   vgchange -a n /dev/vg03   # Deactivate volume group
	   vgchange -c y /dev/vg03   # Enable volume group for HA cluster
	   vgchange -c y -S y /dev/vg03 # Enable volume group for HA cluster
					  and mark as sharable
	   vgchange -a e /dev/vg03   # Activate volume group in exclusive mode
	   vgchange -a s /dev/vg03   # Activate volume group in shared mode

      Activate all volume groups;  activate those that are marked for
      membership in a high availability cluster in exclusive mode:

	   vgchange -a y

      Activate all volumes that are marked for membership in a high
      availability cluster in exclusive mode:





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	   vgchange -a e

 WARNINGS
    Ordinary Operation
      In ordinary operation (i.e., without the optional high availability
      software), it is possible to activate a volume group for read-write
      access from more than one physically connected system, leading to a
      high potential for data corruption.  Therefore, if access is desired
      from more than one system to a single volume group, it is important
      that only one system activate the volume group for read-write access;
      the other systems can use read-only access.  There is no problem if
      all systems activate the volume group for read-only access.

      Furthermore, volume group information is only read from the disks
      during volume group activation.  Dynamic changes to the volume group
      such as the following are not propagated to other systems sharing the
      volume group:

	   Logical volume configuration changes.

	   Changes to the status of the mirrored extents.

	   Bad-block relocation that occurs during write operations.

      Because of these limitations, when sharing volume groups between
      systems it is recommended that logical volumes be accessed only by one
      system at a time.	 If logical volumes need to be accessed
      simultaneously, the logical volumes should not be mirrored and should
      not have bad-block relocation turned on, or all systems should use
      read-only access to the logical volumes.

 SEE ALSO
      mount(1M), vgcreate(1M), vgextend(1M), vgreduce(1M), vgdisplay(1M).

      If MC/ServiceGuard is installed: cmcheckconf(1M), cmquerycl(1M), and
      Managing MC/ServiceGuard.


















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