Using snapshots can cause USN Rollback and other problems. Mark Ramey from the Microsoft AD team has an excellent blog entry that you can read for more info.
I added the word Warning to the title of this blog because I've seen a few blogs, posts, and articles that may lead people to believe that this can all be done with a few mouse clicks. This is not the case, it is not hard but there are some major prerequisites and steps that people have to be aware of.
A few screenshots from my lab using VMware workstation. These options exist in most hypervisor products.
|Cloning in VMware Workstation 8|
|Snapshot in VMWare Workstation 8|
***WARNING*** You can't just use the GUI and start cloning and taking snapshots without causing issues in a domain/forest with multiple DCs. You can't manually copy the virtual machine files. VMWare workstation 8 and the current VMWare products don't support these features.
To take advantage of these features the virtualization host must support VM Generation ID. I'm guessing by the time Windows 8 is released all major vendors will support this but that means most folks will have to upgrade their hypervisor.
Microsoft currently has two really good documents that are a must read for anyone interested in these new features
Test Lab Guide: Demonstrate Virtualized Domain Controller (VDC) in Windows Server "8" Beta
Understand and Troubleshoot Virtualized Domain Controller (VDC) in Windows Server "8" Beta - written by Ned Pyle - Outstanding document!!
I won't repeat the documents but some important sections
Steps to deploy a cloned virtualized domain controller
1. Create the customized DcCloneConfig.xml file on a source domain controller
2. Detect incompatible programs on the source domain controller
3. Ensure the PDC emulator runs Windows Server "8" Beta, is not the clone source, and is available
4. Authorize the source domain controller for cloning
5. Shutdown the source domain controller and copy its disk
6. Create a new clone virtual machine using the copied disks
7. Start the source and cloned domain controller, then allow cloning to occur
For those that are fans of the GUI
There is no task-oriented graphical management program for VDC cloning in Windows Server "8" Beta; the provisioning steps are performed manually or using Windows PowerShell
Steps to restore a DC snapshot
1. Take snapshot of DC
2. Create a new Group Policy
3. Validate GP replication (SYSVOL replication)
4. Restore DC Snapshot
You can read the the documents to get a lot more info. Ned's document is 162 pages...Ned is the king of documentation and writing :)
As I start using this feature more and eventually use this in production in the future I hope to write more on these features. I won't try to replicate Ned's excellent document but there is going to be more to come.