We have a number of clients who are keen to go virtual when buying new servers, but are at the lower end of the scale when it comes to need. Basic setup for these guys is:
2 ESX hosts, 1 SAN, 1 Physical Server for AD, DNS, DHCP, etc.
The question I've been trying to answer is, how to not have to go to a second physical server. This has come about as vCentre wont run on an AD server. DNS is the main issue as an AD integrated DNS is the easiest to manage (for me anyway). What really needs to be in DNS to make vMotion work? Do we need just a forward lookup zone with the ESX host names to keep vCentre happy? Or does it need to know about the whole network? These networks, once set up, will typically not change. Can we just put entries into host files?
In reality, you can run AD, DNS,etc virtual. Since you have multiple hosts, for the most part you will probably not have any real DNS issues ever since you can have 2 DNS servers and use DRS rules to set them so they are never on the same host. This way you can patch hosts without having to worry (as you manually move the vm's together when needed.
In order for your servers to come up nice and clean they need to find the storage and the vcenter server needs to find everything. For such a small environment i would suggest just using host files for the couple of real critical startup systems and ensure your AD controllers are set to start before anything else and leave a good 240second delay before starting anything else to make sure AD services kick in before the other services startup.
The host entries will help you out when the hopefully rare occurance that your storage goes down or you need to shut everything down.
Thanks for the reply Rumple. Just about every tech paper goes on about having a physical DNS, hence my concerns. And of course we have one physical server we can configure. As long as a non-AD integrated DNS will do the job, I'm fine with AD on a VM (well, 2 as you suggested). Part of the reason for the post was that I had attempted VC on a VM but kept on having disconnections. I have the whole weekend to reconfigure the setup again and will test if it is stable enough with VC and DNS on the physical. Cheers
I've run both virtual and physical vCenter servers with no problems...ok, no problems when there were more then 1 ESX host 🐵
I still like having a physical management server (if nothing else I can plug a USB drive in and do some backups or data moves,etc) but I've worked around the problem every time.
Ps - I still take snapshots for image level backups of DC's...but I always make sure I have a weekly or more system state so I can restore the vm, boot into AD recovery move and run the system state restore prior to bringing the box online.