The deduplication feature is integrated with the SnapVault secondary license. This feature increases the efficiency of data backup and improves the use of secondary storage.
The behavior of deduplication
with SnapVault is similar to the behavior of deduplication
with qtree SnapMirror, with the following exceptions:
- Deduplication is also supported on the SnapVault destination volume.
- The deduplication schedule depends on the SnapVault update schedule on the destination system.
However, the deduplication schedule on the source system does not depend on the SnapVault update schedule, and it can be configured independently on a volume. You can set manual schedules on a SnapVault destination volume.
- Every SnapVault update (baseline or incremental) starts a deduplication process on the destination system after the archival Snapshot copy is taken.
- A new Snapshot copy replaces the archival Snapshot copy after deduplication finishes running on the destination system. (The name of this new Snapshot copy is the same as that of the archival copy, but the Snapshot copy uses a new timestamp, which is the creation time.)
- You cannot configure the deduplication schedule on the destination system manually or run the sis start command. However, you can run the sis start -s command on the destination system.
- The SnapVault update does not depend on the deduplication operation. A subsequent incremental update is allowed to continue while the deduplication operation on the destination volume from the previous backup is still in progress. In this case, the deduplication operation continues; however, the archival Snapshot copy is not replaced after the deduplication operation is complete.
- The SnapVault update recognizes the deduplicated blocks as changed blocks. Thus, when deduplication is run on an existing SnapVault source for the first time, all saved space is transferred to the destination system. The size of the transfer might be several times larger than the regular transfers. Running deduplication on the source system periodically will help prevent this issue for future qtree SnapMirror transfers. You should run deduplication before the SnapVault baseline transfer.
Note: You can run a maximum of eight concurrent deduplication operations on a system. This number includes the deduplication operations linked to SnapVault volumes and those that are not linked to SnapVault volumes.