A lot has been said about problems with using snapshots with Domain Controllers and most of what has been said simply translates to
"DO NOT DO IT!"
However, based on how things work and why the problems happen I am not sure that this statement applies to all cases.
USN rollback is caused when you revert a single DC back and the USN number of the local copy is lets say 10 but on its replica partner has the reverted DCs USN of 20. Some people ask the question "well how is it that when i restore a DC from a backup i bring it to same state reverting USN and this is not an issue" for one the database invocation ID is changed on restore and the system marks the server and database as restored and thus knows how to proceed with proper replication. This is obviously not the case with snapshot revert.
Now for questions I have to confirm my theory:
CASE 1
so what happens when you have a single DC environment or SBS system? I would this that in the single DC system the snapshots should be perfectly ok for Domain Controller as it has no replication partner....Can anyone at VMware confirm this??
CASE 2
Also what if you have 2 DC's and you want to use snapshot prior to an upgrade and do the following:
1. shutdown replication between servers using "repadmin /options +DISABLE_OUTBOUND_REPL"
2. Take a snapshot of both servers and enable replication back.
and then if something goes wrong you should be able to safely revert backup IF and ONLY IF you revert BOTH DC's back to the same state and enable replication back as it was disabled during snapshot.
Above 2 cases i would think should be ok and would not cause any USN rollback issues or cause any problems on the domain. Can anyone confirm this as i have not had the chance to test it and even if i do you never really know 100% if any damage occurs in database level even if all checks come back good.