Update (3/13/2013): The versions have been updated due to an issue found in the versions of 5.0 that was previously posted.
Alright, what we've all been waiting for, the ability to clone domain controllers til the cows come home! Not only that but now we can snap, restore, snap, restore, etc! Well, kinda. At least we can clone DCs using a supported process which is well documented on TechNet (links below) and if we do snap, restore we won't break our AD. So what changed to make this possible?
Microsoft introduced the VM-Generation ID specification with Windows Server 2012. This feature allows hypervisor vendors to expose a generation ID for a virtual machine to the guest operation system. Applications that depend on vector-clock synchronization, such as Active Directory, can use this data to understand the state of the virtual machine and react accordingly. In the case of Active Directory, the mechanism triggered is the DC Safegaurd process. With DC Safeguard, if a virtual machine is rolled-back the domain controller reacts by tossing out the RID pool and updating its invocation ID. This means USNs can't be reused (as could be the case in roll back scenario) and the new invocation ID means previous changes on this DC will be replicated back to it. An additional benefit to VM-Generation ID is the ability to support DC cloning. Using this process to deploy new domain controllers will greatly simplify the deployment process and reduce the time to production for new DCs.
The following releases of VMware vSphere have VM-Generation ID functionality:
- VMware vSphere 5.0 Update 2 (both vCenter Server and vSphere hosts must be running 5.0 Update 2)
- VMware vSphere 5.1
It's a good idea to read up on exactly how all this stuff works. A couple of links below should give you all the info you need.
Introduction to Active Directory Domain Services Virtualization (Level 100): https://technet.microsoft.com/en-us/library/hh831734.aspx
Virtualized Domain Controller Technical Reference (Level 300): https://technet.microsoft.com/en-us/library/jj574214.aspx