VVR enables you to create snapshots that are images of the online data volumes at a given point in time. The data in the original volume may change; however, the snapshot can still be used as a stable and independent copy for various purposes. VVR provides two methods of creating snapshots: instant snapshots and traditional snapshots.
Note If the Secondary RVG is inconsistent, then VVR does not allow you to create snapshots of the volumes under this RVG.
The instant snapshot feature is a separately licensed feature of VVR. The advantages of this method over the traditional snapshot method are that the snapshots are available immediately, and they may be space-optimized, thus requiring less space than the traditional snapshots. For more information on instant snapshots, see Using the instant snapshot feature.
With the traditional snapshot method, depending on the size of the volume, the time required for initial synchronization of the plexes can be very large. For more information on traditional snapshots, see Using the traditional snapshot feature.
After a volume has been prepared for the instant snapshot feature, you cannot use it to take a snapshot using the traditional snapshot method. To use the traditional snapshot method, you must first unprepare the volume. Thus, you cannot use the same volume for both the traditional method and the instant snapshot method at the same time.
If an RVG contains a volume set, the
snapshot command can be used to take snapshots of its data volumes.
If an RVG consists of VxVM ISP volumes, then you can create only instant full or space-optimized snapshots of the volumes in the RVG. When creating instant space-optimized snapshots, make sure you create the cache object beforehand because the
cachesize parameter is not supported for an RVG with VxVM ISP volumes.