I’ve been asked over and over and over how to upgrade from a Windows Server 2008 R2 Hyper-V cluster to a Windows Server 2012 Hyper-V cluster. You cannot do an in-place upgrade of a cluster. What I’ve said in the past, and it still holds true, is that you can:
- Buy new host hardware, if your old hardware is out of support, build a new cluster, and migrate VMs across (note that W2008 R2 does not support Shared-Nothing Live Migration), maybe using export/import or VMM.
- Drain a host in your W2008R2 cluster of VMs, rebuild it with WS2012, and start a new cluster. Again, you have to migrate VMs over.
The clustering folks have another way of completing the migration in a structured way. I have not talked about it yet because I didn’t see MSFT talk about it publicly, but that changes as of this morning. The Clustering blog has details on how you can use the Cluster Migration Wizard to migrate VMs from one cluster to another.
There is still some downtime to this migration. But that is limited by migrating the LUNs instead of the VHDs using unmask/mask – in other words, there is no time consuming data copy.
Features of the Cluster Migration Wizard include:
- A pre-migration report
- The ability to pre-stage the migration and cut-over during a maintenance window to minimize risk/impact of downtime. The disk and VM configurations are imported in an off state on the new cluster
- A post-migration report
- Power down the VMs on the old cluster
- You de-zone the CSV from the old cluster – to prevent data corruption by the LUN/VM storage being accessed by 2 clusters at once
- Then you zone the CSV for the new cluster
- You power up the VMs on the new cluster
Read the post by the clustering group (lots more detail and screenshots), and then check out a step-by-step guide.
Things might change when we migrate from Windows Server 2012 Hyper-V to Windows Server vNext Hyper-V, thanks to Shared-Nothing Live Migration 
EDIT#1:
Fellow Virtual Machine MVP, Didier Van Hoye, beat me to the punch by 1 minute on this post He also has a series of posts on the topic of cluster migration.
Hi Aidan.
Can you explain what you mean by de-zone the CSV and zone the CSV ? How would this be done with iSCSI storage?
Consult your SAN documentation/manufacturer. It’s the process where you permit machines to connect to a LUN or virtual disk in your SAN, possibly done using IQN or IP addresses of the hosts in question.
Hey Aidan,
Big question on this. All I’ve read previously suggested that CSV 2.0 requires new volumes to be created. However, the guide for using the Cluster Migration Wizard does not create a new volume, it just transfers ownership of it from the 2008 R2 Cluster to the 2012 Cluster. So my question is, do you in fact need to create a new volume and migrate the VMs across between clusters to take advantage of CSV 2.0?
Thanks,
– Will
CSV does not create a new volume. Using the cluster migration wizard, you simply re-zone the CSV LUN.