- ONTAP 9
- When a SnapMirror relationship is created and updated (either manually or via a schedule) a new snapshot is created on the Source volume.
- This snapshot is the most recent snapshot in the volume and will be used as a base snapshot for the transfer.
- The SnapMirror engine will then identify the differences between the new base snapshot and the last replication snapshot that was created for the previous transfer (referred to as the "common base snapshot").
- These differences are then transferred over to the Destination volume.
- This data can include data blocks, user files, snapshot copies, LUNs, and other data within the volume.
- When the transfer is complete, the latest snapshot in the volume is now the "common base snapshot" until the next update is triggered.
- SnapMirror requires the common base snapshot to exist on both the Source and Destination volumes for updates. If not, the operation will fail with a
No common snapshoterror.
cluster2::> snapmirror resync -source-path svm1:vol1 -destination-path svm2:vol2
Error: command failed: No common Snapshot copy found between svm1:vol1 and svm2:vol2.
cluster2::> snapmirror initialize -destination-path svm2:vol2
cluster2::> snapmirror show svm2:vol2
Source Path: svm1:vol1
Destination Path: svm2:vol2
Unhealthy Reason: Transfer failed.
Last Transfer Type: initialize
Last Transfer Error: Destination volume "svm2:vol2" must be an empty data-protection volume.
(show output has been shortened)