Comment Re:gotta have a night light server (Score 1) 464
Speaking from VMWare land here, YMMV if you're Hyper-V (more on that later)
What we do is a soft lock on our first AD server, SQL box behind VirtualCenter* and vCenter* server so that they are always on host #1. If there's some maintenance going on, we have to disable that rule just to take down host #1. It will move if that box fails, but not before. In the case of a dark datacenter we know to turn that box on, connect to it directly and fire those three boxes up in order. Beyond that it's back to business as usual.
There's a doc from VMWare about why to keep one physical AD server, but I can't remember why.
Now if you're on Hyper-V you get to deal with one of the stupidest architectures, in my opinion. If you're using the clustered filesystem, you need AD to mount it. If your AD server is on the clustered filesystem, you can't mount the shared FS. I guess you *really* need a physical AD server in that case. Why exactly do you need something so high level as AD to get to something as low-level as a filesystem that's behind something as low-level as the hypervisor is beyond me. I could see for high level, tightly integrated services, but at this level it's just bad design.
* we don't do that any more because we've had a run on bad HBAs that cause SAN issues, and there are problems managing your hosts on the san when your san is having problems. They're still virtual, just not on the cluster, on a standalone box on the side built for 'special' cases.