Windows Server 2012 has a built-in tool for migrating VMs between clusters that, by all accounts, works very well. But it has its foibles when it comes to moving Highly Available VMs (and honestly, why run a cluster if you're not going to run HAVMs?) and is a bit of a faff if you're moving to entirely new equipment, storage and all. You have to migrate from the old cluster to the new cluster on the same storage, and once that migration is complete, then migrate the storage. Which is lots of cross cabling and temporary set up and scope for things to go wrong when you're an idiot (*cough*).

But all the articles on the subject, including that authoritative MSDN blog post linked above, mention SCVMM 2012R2 as another method. Yet if you try to Google up instructions for that, all you come up with is the same reference to "you can do it with VMM... but this is a guide on using the built in tool".

It turns out that's because the VMM method is laughably simple. But still--it's nice to see that written down, hence this blog post. This is how to migrate highly available virtual machines (HAVMs) to a new cluster on new storage using Virtual Machine Manager 2012R2.

First up--set your new cluster up in the usual fashion. Configure the witness disk in quorum if you need, the new cluster shared volume, the network settings. Easy. Then set up your Virtual Machine Manager installation after installing the prequisites and the database (a separate download from VLSC; SQL has to be installed before VMM). Straightforward stuff, especially if this isn't your first cluster (as presumably it isn't, in this guide on migration ).

Once VMM is up and running and updated, open the same setup.exe on your new hosts and install the local agent from the splash screen. You can then add the cluster in the VMM console.

On your existing hosts, in the old cluster, remove the existing VMM agent if you have one and then install the new agent as you just did. You don't need any restarts here. Once the hosts are on the new agent, you can add them into the new VMM instance as well. In doing this, VMM will create all the logical networks etc. that the existing VMs use.

Now we have the one bit of configuration needed--the networking. In the properties of each of your new virtual hosts, go to virtual switches and recreate what you have on your old hosts. I've kept it simple in my environment and use a single network, so I've created a new virtual switch with the same name, as an External adapter, and tied it to the relevant network adapter. I've also allowed the management OS to share the connection because I want to go over my teamed 10GbE connection for everything, but you can tweak as suits your needs. Make sure these connections are set up the same on all your hosts.

Then, in the Hardware section of the same properties window, find the network adapter(s) you selected above, go to Logical network underneath, and tick the box for the network that your existing VMs use.

At that point... you're good to go, more or less. I had one final error to resolve before I could migrate VMs though (that only flashed up halfway through moving my first VM):

Error (2912): "An internal error has occurred trying to contact the <HOST_NAME> server: NO_PARAM: NO_PARAM

"Oh bugger," quoth I. But it turned out to be easy to resolve: check a couple of certificates' thumbprints, and run a PowerShell command if they don't match. I also installed BITS on my virtual hosts (along with everything that feature required) as part of troubleshooting this, which didn't fix the error, but is probably required anyway--it was certainly installed on my old hosts.

Once you've checked the above and resolved it if necessary, the process of migration goes thus:

• Select the virtual machine on your old cluster. Shut it down (no live migrations here, I'm afraid).
  
• Once it's powered off, select Migrate Virtual Machine at the top, as if you were live migrating within the cluster.
  
• Select one of your new hosts.
  
• Click next until it migrates.
  

That's it. That's literally it. That's why there's no article online about how to do this, because it's so blindingly obvious even I could work it out. At the end of the above, your VM will be sat on your new host, awaiting startup, unless you ticked the box to start it after migration anyway. It will have installed the new VM components. It will be connected to the network. It will, in summary, just be ready. It's a marvellous thing.

It gives me a warning about this being a one-way process due to the host OS difference (2008R2 to 2012R2), but that's fine. I'm now migrating my VMs one at a time without having to do any weird cabling or set up. All my equipment and software is configured as it needs to be anyway--I've not had to do anything temporary that might cause me grief in the future.

The workload for my next week just got a lot lighter