HP-UX 11i v3 - LVM Volume Group Version Migration (September 2010)

HP recommends using vgversion to take advantage of:

The new features in the newer volume group versions.

The extended limits supported by the newer volume group versions.

For more information on the new features and the limits supported by various volume group versions,

see the LVM Version 2.0 volume groups in HP-UX 11i v3 white paper.

Prerequisites

To migrate a volume group from one version to another, you must meet the following prerequisites:

The volume group must be deactivated during migration.

The volume group must be cluster unaware (vgchange –c n) before changes are made. After the

volume group migration, you can then make the volume group cluster aware (vgchange –c y).

No physical volume in the volume group is configured as a cluster lock disk for a high

availability cluster.

All physical volumes belonging to the volume group must be accessible.

For more information, see the individual volume group migration sections.

Metadata space requirements for Version 2.x volume groups

When compared to a Version 1.0 volume group, a 2.x volume group can have more physical

volumes and logical volumes. The maximum size supported for logical volumes and physical volumes

is increased in Version 2.x volume groups. As a result, a Version 2.x volume group needs more space

for metadata than a 1.0 volume group. The metadata of a Version 1.0 volume group is stored at the

beginning of the physical volume. The major portion of the Version 2.x volume group metadata is

stored at the bottom of the physical volume, providing the flexibility of dynamically expanding the

physical volume to accommodate more space for the metadata.

The additional space required for the Version 2.x volume group can be provided by using either or

both of the following approaches:

Dynamically extend the physical volume from the storage end and run the vgversion command

later. The vgversion command automatically considers the additional space at the end of the disk

to keep the metadata.

Let the vgversion command automatically convert the unused free extents from the end of the

physical volume into metadata space.

The free space at the end of the disk is given preference over the unused free extents towards the end

of the physical volume.

If the disk capacity increased from the storage side is more than what is required to keep the

metadata, the extra space is left unused. To convert the extra space into user extents, use the

vgmodify command. Alternatively, you can reduce this extra space from storage end by using

dynamic LUN contraction.