Well, we’ve been trying to come up with a decent way to backup NetApp snapshots to tape (SnapMirror To Tape), so we evaluated all the available methods of using NDMP backups.
- There’s Image Backup in two different variants – FULL and DIFFerntial
- There’s SnapMirror To Tape
So the Image Backup is one of the ways. However the DIFFerntial backup only works for CIFS and NFS shares (which we don’t use). We only have FC luns (or rather FCoE luns), so there’s only a single (or in case of the boot luns more than one) file in each volume. With that however, each run of the Image Backup with the DIFFerential option, it’s gonna backup the full size of the volume (plus the deduplicated amount).
The SnapMirror To Tape option presents another problem: We intend to use SnapManager for SQL/Oracle, which creates “consistent” snapshots of the database luns. However the SnapMirror To Tape backup doesn’t have an option to use an already existing snapshot, but creates another one. Which puts the whole SnapManager business down the curb. So we either do use a SnapMirror To Disk from one database lun to another controller and then run the SnapMirror To Tape from the second controller or come up with another way to back them up to TSM.