FastResync (FR) enables you to split off a plex from a mirrored volume, manipulate it, and then reattach it to the original volume without doing a complete resynchronization of the volume. FastResync is a separately licensed feature of VxVM.
FR maintains a bitmap of changes to the volume while the plex was split off, and also of changes to the split-off mirror. When the plex is attached, only the blocks represented in the map are resynchronized.
You can use FR to perform the snapback operation after the off-host processing operation is complete.
The operations performed by the
vxrvg snapback commands are based on one of the following conditions:
snapshotcommand creates a simple snapshot without any FR bitmaps. A
vxrvg snapbackoperation then results in a full resynchronization of the plexes.
snapshotcommand creates a snapshot with a non-persistent FR bitmap. A
vxrvg snapbackoperation performs a FastResync, but if the system reboots at any time after the snapshot operation, the information in the FR bitmap is lost and a full resynchronization takes place.
vxrvg snapshotcommand creates a snapshot with persistent FR bitmap. A
vxrvg snapbackoperation performs a FastResync even if the system reboots at any point in time after the snapshot operation.
For more information on Persistent and Non-Persistent FR, see the Veritas Volume Manager Administrator's Guide.
To enable FR on a data volume, type:
Do this for all the data volumes in the RVG that you want to access.
Refer to the Veritas Volume Manager Administrator's Guide for more information.