Best Practices for Virtualization of Domain Controllers
I am frequently asked what my stance on virtualizing domain controllers is and my response is YES!
Having your DCs virtualized allows you to take full advantage of your virtual infrastructure and allows your DCs to benefit from the flexibility and reliability that virtualization offers.
The management hurdles and configuration steps are far worth the added benefits in this case.
In the past it was often difficult and sometimes not viable to virtualize all domain controllers in an environment. Potential login issues could occur if the host system was on a domain where the only reachable DC is a VM on the same host. USN rollback issues were likely to occur when utilizing snapshots involving any length of time. Cloning a DC was outright unthinkable due to the underlying complexities and unique identifiers for each DC in the environment.
Hyper-V has come a long way in resolving several of these concerns.
I won’t run a play-by-play recap on this issue as there is already some excellent documentation on this subject via TechNet.
This link is a great one to get you started on the basic concepts and practices. It’s written with Hyper-V 2008 R2 in mind, but most everything still applies.
Another page has been created citing the new added features regarding DC virtualization in Server 2012. Relevant page can be found here.
Together these two documents will provided all the information you need to successfully and safely virtualize your DCs.