Domain Controllers - to P2V or not to P2V
It’s good to see other administrators discussing whether or not to P2V domain controllers, and even better to see that others are recommending the same as I did in my recent post Small business P2V migrations. VMware Communities: VMWare esx 3.5& Windows Server 2003 … is a forum discussion where this topic is discussed in detail. What’s great about this discussion is that it goes beyond the P2V strategy and in to whether or not all DCs in your environment should be VMs.
Some highlights from the forum discussion:
“So it is a bad idea to convert dc’s from physical to virtual correct?
It’s a much better idea to stage a new VM and then run dcpromo. With a new VM you don’t have to worry about old device drivers, management software, etc. If you do clone:
1) You must perform a cold clone. If you do a hot clone, when you bring the VM up it will be out of sync.
2) If you perform a cold clone and then power on the new VM, you must ensure that the old physical server is never powered on again (at least not with network connectivity).”
Also in this discussion is a link to a VMWorld 2006 Presentation titled TAC 9710 - Virtualizing a Windows Active Directory Domain Infrastructure which not only talks about P2V-ing domain controllers but also covers challenges to virtualizing Active Directory such as:
- Clock synchronization
- Network performance
- Multi-master replication model
- Security
- Potential single point of failure
- Disaster recovery
The VMWorld presentation provides the following migration best practices slide (click on it for a larger image):
Other links that are related to Active Directory, Domain Controllers and issues after P2V migrations:
How to detect and recover from a USN rollback in Windows Server 2003
This article describes a condition that occurs when a domain controller that is running Microsoft Windows 2000 or Microsoft Windows Server 2003 starts from an Active Directory database that has been incorrectly restored or copied into place. This condition is known as an update sequence number rollback, or USN rollback.
When a USN rollback occurs, modifications to objects and attributes that occur on one domain controller do not replicate to other domain controllers in the forest. Because replication partners believe that they have an up-to-date copy of the Active Directory database, monitoring and troubleshooting tools such as Repadmin.exe do not report any replication errors.
VMware Communities: P2Ving domain controllers …
All, how do you P2V a w2k3 domain controller? I run though the normal p2v process, but I end up with a vm that doesn’t work right. The system event log shows events on disk signatures, replication failures, etc.
Error message when you try to set an IP address on a network adapter
When you trying to set the IP address on a network adapter, you may receive the following error message:
The IP address XXX.XXX.XXX.XXX you have entered for this network adapter is already assigned to another adapter Name of adapter. Name of adapter is hidden from the network and Dial-up Connections folder because it is not physically in the computer or is a legacy adapter that is not working. If the same address is assigned to both adapters and they become active, only one of them will use this address. This may result in incorrect system configuration. Do you want to enter a different IP address for this adapter in the list of IP addresses in the advanced dialog box?
CAUSE
A network adapter with the same IP address is in the registry but is hidden in Device Manager. This can occur when you move a network card from one PCI slot to another PCI slot.
RESOLUTION
To resolve this problem, uninstall the ghosted network adapter from the registry using one of the following methods:
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Tags: esx, issues, microsoft, P2V, planning, replication, vmware, windows
