Veritas Volume Manager 5.0.1 Administrator's Guide, HP-UX 11i v3, First Edition, November 2009

allows VxVM to track the relationship between volumes and their snapshots even

if they are moved into different disk groups.

The snap objects in the original volume and snapshot volume are automatically

deleted in the following circumstances:

■ For traditional snapshots, the vxassist snapback operation is run to return

all of the plexes of the snapshot volume to the original volume.

■ For traditional snapshots, the vxassist snapclear operation is run on a

volume to break the association between the original volume and the snapshot

volume. If the volumes are in different disk groups, the command must be run

separately on each volume.

■ For full-sized instant snapshots, the vxsnap reattach operation is run to

return all of the plexes of the snapshot volume to the original volume.

■ For full-sized instant snapshots, the vxsnap dis or vxsnap split operations

are run on a volume to break the association between the original volume and

the snapshot volume. If the volumes are in different disk groups, the command

must be run separately on each volume.

Note: The vxsnap reattach, dis and split operations are not supported for

space-optimized instant snapshots.

See “Space-optimized instant snapshots” on page 356.

See the vxassist(1M) manual page.

See the vxsnap(1M) manual page.

Effect of growing a volume on the FastResync map

It is possible to grow the replica volume, or the original volume, and still use

FastResync. According to the DCO volume layout, growing the volume has the

following different effects on the map that FastResync uses to track changes to

the original volume:

■ For a version 20 DCO volume, the size of the map is increased and the size of

the region that is tracked by each bit in the map stays the same.

■ For a version 0 DCO volume, the size of the map remains the same and the

region size is increased.

In either case, the part of the map that corresponds to the grown area of the

volume is marked as “dirty” so that this area is resynchronized. The snapback

operation fails if it attempts to create an incomplete snapshot plex. In such cases,

you must grow the replica volume, or the original volume, before invoking any of

Understanding Veritas Volume Manager

FastResync