Veritas FlashSnap Point-In-Time Copy Solutions 5.0.1 Administrators Guide, HP-UX 11i v3, First Edition, November 2009

Figure 2-1
Examples of disk groups that can and cannot be split
X
Snapshot
plex
Volume
data plexes
Volume
DCO plexes
Snapshot
DCO plex
X
Split
Volume
DCO plex
Snapshot
DCO plex
Volume
DCO plex
Snapshot
plex
Volume 1
data plexes
Volume 1
DCO plexes
Volume data
plexes
Volume DCO
plexes
Split
?
The disk group can be split as the DCO plexes are on
dedicated disks, and can therefore accompany the
disks that contain the volume data.
The disk group cannot be split as the DCO plexes
cannot accompany their volumes. One solution is to
relocate the DCO plexes. In this example, use an
additional disk in the disk group as an intermediary
to swap the misplaced DCO plexes. Alternatively, to
improve DRL performance and resilience, allocate
the DCO plexes to dedicated disks.
The disk group can be split as the DCO
plexes can accompany their volumes.
However, you may not wish the data in
the portions of the disks marked “?” to
be moved as well.
The disk group cannot be split as this
would separate the disks that contain
the data plexes of Volume 2. Possible
solutions are to relocate the
snapshot DCO plex to the disk
containing the snapshot plex, or to
another suitable disk that can be
moved.
?
??
Snapshot
plex
Snapshot
plex
Volume
data plexes
Snapshot
DCO plex
Volume 2
data plexes
Snapshot
DCO plex
Setting up volumes for instant snapshots
Preparing a volume for instant snapshot operations
34