You can also schedule a snapshot prior to the backup. The backup would look like this:
1. Install backup agent on the COS (Console) -- be it Netbackup, Legato, CommVault, etc
2. Run a pre-command script that would snapshot the running VM
3. Backup all files except *.vmsn, *-000001.vmdk and *.vswp
4. Run a psot-command script that deletes (applies) the snapshot
Do this for all runnng VM's