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DC on Hyper-V Cluster

  I have two physical servers that are running 2012r2 and I want to create a hyperv cluster using these two physical servers and one physical NAS.  I have done this previously without issue but I had an external domain controller in those situations.  

  In this situation I want the DC to reside on the hyperv cluster, for example on vmhost1 and an exchange server to run on vmhost2.  I want them in a virtual environment so that they can fail over if one of the physical hosts fail.

  I have read many docs for and against this scenario and can't find a conclusive answer.  I am sometimes told that I need to make the nodes of the cluster DC's themselves so that a domain structure exists when they start.  Others say that you can create the one and only DC on the vmhost and that if everything needs to reboot the vmhosts will startup up and start the DC vm even though the DC needs to be on first.

  I was also told that exchange will not function on a vm is the host is a DC and that if I do virtualize my DC that it cannot be part of the failover cluster and must be manually failed over.

  I am looking for general guidence on this type of setup and tips on how to implement it if you have done so already.  How do I build the hyperv cluster without a DC to start with?

Thanks in advance.
3 Solutions
Brad BouchardInformation Systems Security OfficerCommented:
I can tell you've already done a lot of research so I'll save you some time.  I've had experience with both environments and it all comes down to how you take care of your servers.  If you are careless then your servers will probably be set up in a careless manner and will fail and cause you trouble.  If you are careful though then you have nothing to worry about.  The failover cluster is a great idea, and you're already on the right track.

As far as the DC being virtual, there have been arguements against this since the inception of virtualization.  Let me tell you what counts to me:  real world experience.  And my real world experience as an IT consultant with a firm that managed over 60 clients and nearly 2000 computers (several hundred of which were servers, and several dozen of these were DCs) and literally never had a single problem with a domain controller aside from usual Windows errors; nothing directly related to AD Directory Services though.  So take that or leave it, but that's 7 years of experience virtualizing DCs with no problems.

Also my recommendation is that you don't make the physical hosts DCs.  Sure if they go down you have to wait for the VMs to come back up, but you don't have to wait that long and your host will try to reconnect to the domain every so often in this event.

I am not sure about Exchange not working on a host that is also a DC, but I've not heard of that.
Cliff GaliherCommented:
1) *NEVER* install the ADDS role and the hyper-v role in the same OS. so your physical nodes should not be DCs. Hyper-V should always be the only role.

Now you can run a separate non-hyper-v single DC, or you can virtualize your DC. 2012 virtualizes ADDS much better than previous versions so no worries there. But don't try to make hyper-v coexist with ADDS. There is pain there.

2) ADDS cannot be on a clustered node (even without hyper-v.) Failing over ADDS is also not supported. Since ADDS is multi-master, there is no need (and therefore no supporting code for) an ADDS cluster. Redundancy is provided by multiple discreet DCs.

3) Exchange has limited mobility rights in its licensing. Putting it in a cluster is also a bad idea both legally and technologically. The appropriate redundancy for exchange is DAG.

So if those are your only services, a cluster may not be a good fit anyways. But if you have other roles or software that can benefit from a cluster, the above should still be avoided.
1st off all Exchange on DC is supported but not recommended, its true. U can check Microsoft documentation

2nd thing, do not put any role on Hyper-V physical server hosts other than Hyper-V

Its not good from performance and also you break free Vm licenses in case of windows 2102 standard edition
I always prefer plain Hyper-V servers \ Hyper-V clusters

Active directory is multi master replication model and  in reality it works better out of cluster with Two DCs (physical \ virtual) which provides you redundancy \ failover \ stable environment and that's how Domain controller HA suppose to.
Clustered DC is not the best method to deploy HA for Domain controllers, I haven't seen in yet with any of my clients even it is possible to do.

However if your environment is small, you can build single virtual DC with always start with physical OS option in Hyper-V settings of that DC VM, but this is best suite for Lab setup because in lab most of the time the only physical server is hyper-v host, unfortunately this is not the case in case of production environment

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compcreateAuthor Commented:
Thank you all for your comments.  I think this is what I am leaning towards welcome your replies:

two physical hosts, vmhost1 and vmhost2.  I will create a DC on BOTH hyperv hosts that is outside of the cluster.  This way it doesnt try to fail over, and I simply have a second DC to handle requests.

Exchange on the other hand, I still want to create a cluster with shared storage that exchange will run off of and attempt to allow that to fail over.  If this is really going to break exchange then I could fall back to a non-auto failover and just fire the vm up on the other host manually in case of an issue.

The other big question is... the two physical hosts need to be domain joined to form the cluster so if the DC is virtual how do I form the cluster before the vm is created?

You can configure DC 1st on both standalone Hyper-V servers, then you can configure cluster by adding both Hyper-V servers in domain
Remember, DC VMs must be set to start with Hyper-V host server at startup and this setting can be found in VM settings in Hyper-V

For Exchange I'd create Exchange VMs outside Cluster and create DAG for which shared storage is not required, because Exchange 2010 onwards required DAG to maintain Mailbox server HA and normal active -passive cluster is not required and its not the method for exchange to build HA
Also you need to create NLB for Exchange CAS servers and hence active - passive cluster is not required for CAS servers as well
Also when you have 2 or more Hub transport servers, HA \ failover \ redundancy is automatically maintained by TWO Hub servers and hence active passive cluster is not required in this case also

In short Exchange 2010 the way it works you did not required active passive failover cluster, however you do required to install Failover cluster feature on Exchange Mailbox servers to build DAG

two physical hosts, vmhost1 and vmhost2.  I will create a DC on BOTH hyperv hosts that is outside of the cluster

I believe above plan will work.

Please check the below blog posts


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