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
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
snapback command with the
-f (force) option to perform the snapback.
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.
vxassist (1M) manual page.
vxplex (1M) manual page.
vxvol (1M) manual page.