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

the commands vxsnap reattach, vxsnap restore, or vxassist snapback.
Growing the two volumes separately can lead to a snapshot that shares physical
disks with another mirror in the volume. To prevent this, grow the volume after
the snapback command is complete.
FastResync limitations
The following limitations apply to FastResync:
■ Persistent FastResync is supported for RAID-5 volumes, but this prevents the
use of the relayout or resize operations on the volume while a DCO is associated
with it.
■ Neither non-persistent nor persistent FastResync can be used to resynchronize
mirrors after a system crash. Dirty region logging (DRL), which can coexist
with FastResync, should be used for this purpose. In VxVM 4.0 and later
releases, DRL logs may be stored in a version 20 DCO volume.
■ When a subdisk is relocated, the entire plex is marked “dirty” and a full
resynchronization becomes necessary.
■ If a snapshot volume is split off into another disk group, non-persistent
FastResync cannot be used to resynchronize the snapshot plexes with the
original volume when the disk group is rejoined with the original volume’s
disk group. Persistent FastResync must be used for this purpose.
■ If you move or split an original volume (on which persistent FastResync is
enabled) into another disk group, and then move or join it to a snapshot
volume’s disk group, you cannot use vxassist snapback to resynchronize
traditional snapshot plexes with the original volume. This restriction arises
because a snapshot volume references the original volume by its record ID at
the time that the snapshot volume was created. Moving the original volume
to a different disk group changes the volume’s record ID, and so breaks the
association. However, in such a case, you can use the vxplex snapback
command with the -f (force) option to perform the snapback.
Note: This restriction only applies to traditional snapshots. It does not apply
to instant snapshots.
■ Any operation that changes the layout of a replica volume can mark the
FastResync change map for that snapshot “dirty” and require a full
resynchronization during snapback. Operations that cause this include subdisk
split, subdisk move, and online relayout of the replica. It is safe to perform
these operations after the snapshot is completed.
73Understanding Veritas Volume Manager
FastResync