@Randy

That's fine, until you have over a certain ammount of storage. I only really know EMC's DMX arrays, but you are looking at 3phase power, tens of amps at a time, you _really_ notice turning off a %age of a couple of hundred disks.

Where I work we have something like 18DMXs, that's a whole lodda power, and cooling. We mainly don't bother with disk based backups, because a tape library doesn't use a fraction of the power/heat footprint. We do however, keep two snapshots of each server, one on two different arrays. Now the trouble with DMX here is that each disk is chopped up into virtual devices, these are then presented to the different machines, this means that you have to make sure that all of the devices on each disk are presented to machines which won't be useing them at the same time. All you have to do is accidentally stick a database onto a disk containing snapshots and it'll never power down.