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 vgchgid(1M)							 vgchgid(1M)




 NAME
      vgchgid - modify the Volume Group ID (VGID) on a given set of physical
      devices

 SYNOPSIS
      /usr/sbin/vgchgid PhysicalVolumePath [PhysicalVolumePath] ...

 DESCRIPTION
      The vgchgid command is designed to change the LVM Volume Group ID
      (VGID) on a supplied set of disks.  It is primarily targeted for disk
      arrays which have capability of creating mirrored Business Copy (BC),
      such as EMC Symmetrix disks, and the XP disk array family, such as
      XP256 and XP512.	vgchgid command accepts a set of raw physical
      devices and checks the following criteria before it alters the VGID:

      +	 All raw physical volume devices in the command line have the same
	 disk type, such as:

	 1) EMC Symmetrix disks with the BCV attributes.  (See EMC
	    documentation.)
	 2) The XP disk array family with BC_SVOL or CA_SVOL attributes.
	    (See XP256/XP512 related documentation.)

      +	 All raw physical volume devices in the command line belong to the
	 same VG.  (See WARNINGS section.)

      Once the checks are successful, the same VGID is set on all the disks.
      It should be noted that for multi-PV volume groups all the physical
      volumes should be split-off and supplied in a single invocation of the
      vgchgid command.

    Options
      vgchgid recognizes the following options and arguments:

	   PhysicalVolumePath  The raw devices path name of a physical
			       volume.

    Background
      Both the EMC and XP disk arrays have a feature which allows a user to
      split-off a set of mirrored copies of physical volumes (termed BCVs or
      BCs) just as LVM split-off logical volumes with lvsplit command.	As
      the result of the "split," the split-off devices will have the same
      VGID as the original disks.  The vgchgid command is needed to modify
      the VGID on the BCV devices.  Once the VGID has been altered, the BCV
      disks can be imported into a new volume group by using the vgimport
      command.

 WARNINGS
      Once the VGID has been changed, the original VGID is lost until a BCV
      device is re-mirrored with the original devices.	If the vgchgid
      command is used on a subset of BCV devices (e.g., two out of four BCV



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 vgchgid(1M)							 vgchgid(1M)




      devices), the two groups of BCV devices would not be able to be
      imported into the same VG since they have different VGID on them.	 The
      solution is to re-mirror all four of the BCV devices and re-run the
      vgchgid command on all four BCV devices at the same time, and then use
      the vgimport command to import them into the same new VG.

      If a disk is newly added to an existing volume group and no subsequent
      LVM operations has been performed to alter the structures (i.e.,
      operations which perform an automated vgcfgbackup(1M)); then it is
      possible a subsequent vgchgid will fail. It will report that the disk
      does not belong to the volume group. This may be overcome by
      performing a structure changing operation on the volume group (for
      example, using lvcreate).

 RETURN VALUE
      vgchgid command returns the following values:

	   0  VGID was modified with no error
	   1  VGID was not modified

 EXAMPLES
      An example showing how vgchgid command might be used.

      1. The system administrator uses the following commands to create the
	 Business Continuity (BCV or BC) copy:

	 1)   For EMC Symmetrix disks, the commands are BCV establish and
	      BCV split.

	 2)   For XP disk array, the commands are paircreate and pairsplit.

	 Three BCV disks are created.

      2. Change the VGID on the BCV disks.

	 vgchgid /dev/rdsk/c0t0d0 /dev/rdsk/c0t0d1 /dev/rdsk/c0t0d2

      3. Make a new volume group using the BCV disks.

	 mkdir /dev/vgbcv
	 mknod /dev/vgbcv/group c 64 0x040000

      4. Import the BCV disks into the new volume group.

	 vgimport /dev/vgbcv /dev/dsk/c0t0d0 /dev/dsk/c0t0d1 /dev/dsk/c0t0d2

      5. Activate the new volume group.

	 vgchange -a y /dev/vgbcv





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 vgchgid(1M)							 vgchgid(1M)




      6. Backup the new volume group's LVM data structure.

	 vgcfgbackup /dev/vgbcv

      7. Mount the associated logical volumes.

	 mkdir /bcv/lvol1 /bcv/lvol2
	 mount /dev/vgbcv/lvol1 /bcv/lvol1
	 mount /dev/vgbcv/lvol2 /bcv/lvol2

 SEE ALSO
      vgimport(1M), vgscan(1M), vgcfgbackup(1M).










































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