Suppose you have some virtual machines (running in eg. ESXi) that are stored on an iSCSI storage array (eg. EqualLogic PS4110). Now suppose you want to set up a backup and restore regime that looks something like this:
- VMs are quiesced
- snapshots are taken
- snapshots are copied to tape
- snapshots are deleted
- tapes are taken offsite
- disaster occurs
- tapes are retrieved from offsite
- snapshots are copied from tape
- VMs recovered from tape are re-started
There seems to be two obvious ways to snapshot the VMs:
- hypervisor creates snapshot (à la the way vSphere Data Protection gets its snapshots)
- SAN creates snapshot (à la the way EqualLogic Auto Snapshot Manager/VMWare Edition seems to work)
What are the tradeoffs I should consider between these two methods of achieving snapshots for the above backup regime?
Are there some fundamental benefits of each of these snapshot methods that apply regardless of the purpose of the snapshot?