Hi Richard, some very long time ago, we hit the need to use two policy sets in environments with two physical tape robots (old 3583, remember them?), small disk pools and large backups. Backups would run up to 24 hours to two tape devices, not enough drives to allocate for synchronous writes for these slow clients. Backup storage pool would again sit waiting for the tape currently in use for the backup. So - switch primary pool every day by policy set and switching backup storage pool dedicating one drive to do the job was a neat workaround that could very easily be automated to get it done every day. Second use-case was a branch office with (that was LTO1) two tape sites of which in the end one was almost always offline for repair. So having one policy set for "site1" and one for "site2" made life much easier for the local TSM operators to handle the outages and kept last level out of the picture. Currently I could only come up with the idea to temporarily bypass some part of the storage infrastructure for maintainance by switching destinations without disruption of backup operations.
Cheers, Markus
