Snapshots are NOT backup solution in any case. If you use snapshots as backup replacement then
1) you're wasting expensive storage space
2) you have lower reliability
3) you generate high disk load when commit snapshots
What is correct use of snasphots:
1) you have to install some patch on your VM
2) take snapshot
3) install patch
4) monitor system behavior in case of patch have broken something for some time
5) commit snapshot if everything is ok, or revert to snapshot if something bad happened.
---
MCSA, MCTS, VCP, VMware vExpert '2009