I attempted to install Windows Server 2012 on a Dell PowerEdge 2850 and found out that the server may not support Server 2012. Is there any downside to running a Windows Server 2012 domain controller from a virtual machine on a Windows Server 2008 R2 server? I know this is possible but I am looking at best practices. I also want to note that this is an additional domain controller as I already have another Windows Server 2012 domain controller on a physical machine (non-virtualized)
The bug I seen in the past was if the DC die, my hyper-v console refused to open. So, like they told try to not create a single point of failure.
Physical hardware is best if possible.
I have seen a lot of chicken and egg type scenarios where people are having problems getting their virtual machines to boot up. They can't log into their virtual machine hosts to fix the problems because the domain controllers aren't running to authenticate them (because they are on the VM hosts having issues). How can you fix the problem if you can't log in? That's not a fun situation to be in.
Virtualized domain controllers are only supported in very specific configurations.
Some of the General rules are to:
1) Never use checkpoints (they can corrupt the active directory database)
2) Use server 2012 only. It resolved virtualization issues(2008 and older had problems)
3) You need more than one VM on multiple hosts that replicate to each other
4) The Domain controllers need to be left on all the time
5) Domain controllers should stand solo (Don't put a DC on a VM Host)
Thus you need to be very careful and put thought into it if you go down this road.
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