The premise of the question seemed to be “how to reduce the size of the snapshot?” and the answer is – Take another snapshot. I agree this is a crappy question…If a DBA came up to this scenario and was asked to reduce the size of the snapshop file by doing a backup and he replied “you can’t backup a Snapshot” and walked away, I would fire them. I would expect the DBA to say “I’ll take care of it” and do another snapshot to reduce the size.