[lmz]

I don't think the diffs are usable that way. They're actually more like an "undo log" in that the snapshot space is taken by "old blocks" when the actual volume is taking writes. It's useful for the same reasons as volume shadow copy: a consistent snapshot of the block device. (Also this can be very bad for write performance as any writes are doubled - to snapshot and to to the real device)

[magicalhippo]

Yeah ok, that makes sense. Write performance is a concern, but usually the backups run when there's little activity.