Thankyou. We use DRS, so it seems when a backup is occuring even if DRS moves the vm to another host, the backup should continue. I assumed that and thank you for the confirmaiton. But a Storage Vmtion could hose the backup, which I guess makes sense too.
I guess then the important issue is whether your VADP enabled backup software can correctly identity the VMs that were moved in a timely manner so as not to miss the next backup cycle.