Integrating Cloned LUNs
Certain disk arrays can create clones of their
LUNs. For example, the HP XP product enables you to split off a set
of LUNs, called Business Copies (BCs), which are copies of existing
Cloned disks have the same information in their
LVM headers as the original disks, which violates LVM's requirement
that each disk have a unique identifier. To make the cloned disks
usable with LVM, use the vgchgid command to change
their volume group identifier (VGID).
All of the physical volumes to be changed must
belong to the same volume group. Therefore, if you are changing multiple
physical volumes, specify all of them in a single invocation of vgchgid. Otherwise, they are assigned different VGIDs.
For example, you have a volume group containing
four physical volumes and need to create a BC for each physical volume.
If you run vgchgid on only two BCs, vgchgid modifies the VGID on those two BCs. If you then run vgchgid again with all four BCs, vgchgid reports that
they belong to different volume groups. To correct this, you can either
run vgchgid on the two unmodified BCs and then
use the four BCs in two separate volume groups, or you can merge back
the two modified BCs and split them off again before finally running vgchgid with all four BCs.
After running vgchgid on a
set of physical volumes, use vgimport to import
them into a new volume group. For example:
Make BC copies and create
new device files using the instructions for the array.
Change the VGID on the cloned
disks as follows:
# vgchgid /dev/rdisk/disk49 /dev/rdisk/disk50
If you are using an HP-UX
release before March 2008, create the volume group group file using the procedure in “Creating the Volume Group Device File”.
Import the physical volumes
# vgimport /dev/vg04 /dev/rdisk/disk49 /dev/rdisk/disk50
Back up the volume group configuration
information as follows:
Activate the volume group
# vgchange -a y /dev/vg04