I am a little bit worried, as there is no easy way of testing the change (obviously, nobody can afford a lab environment completely identical to production). The migration is a one-way road; once we do this, there is now easy way of reverting the change (other than AD recovery on all DCs for the domain). The two questions I have:
- What are typical problems people run into when they switch from mixed mode domain to native mode?
- Do any alternative back-out procedures exist (other than AD recovery on all DCs.)?
- Power off all DCs except the primary.
- Perform a full backup of the system to tape.
- Perform a system state only backup to disk (this will make recovery faster).
- Switch to native mode.
- Test your applications.
If something goes wickedly wrong:
- Restart the DC and perform an authoritative restore of the system state.
- Check that the system is correctly in mixed mode -- if not, restore the entire system from tape. (The system should be in mixed mode; this is just a fall back step.)
- Bring the other DCs back online.
If everything looks good (like I think it will):
- Power on the other DCs.
Of course this could be quite a task if your DCs are plentiful and spread across geographical regions. But, it offers you a way to perform a last minute check while having a way to backout of the process with the least amount of effort.
Editor's Note: Additional information and resources can be found in our Migration Best Web Links.
This was first published in August 2002