Windows Server Technical Preview – Cluster Rolling Upgrade

If you are using Hyper-V some time you could have asked yourself:

How can i upgrade my Hyper-V cluster from one version to another

until Windows Server 2012

In earlier versions of Hyper-V it was quiet difficult to upgrade a cluster. If ou had no new hardware, you had to evict a node from the cluster. This node had to be reinstalled with the new version. After this you had to create a new cluster with this new node. Now you had to schedule a downtime for your VMs and you can import them into the new cluster.

since Windows Server 2012 R2

With the release of Windows Server 2012 R2 there was a new feature called Cross-Version Live Migration. With this new feature it is possible to change a node from the cluster like described earlier. But with Cross-Version Live Migration you are able to live migrate VMs between clusters and hosts wit different versions.

BUT:

• the migration is one-way! it is not possible to migrate a VM from 2012 R2 back to 2012
• You need a downtime to installed the new integration services

what to expect from vNEXT

With the next Version of Windows Server, our dreams come true. In Windows Server Technical Preview we have a new feature called:

Cluster Rolling Upgrade

With Cluster Rolling Upgrade you can reinstall a node of the cluster with the new OS and then rejoin the node to the old cluster. After the node is rejoined to the cluster you can migrate VMs from and to the cluster. The cluster is running in mixed mode until all nodes have been upgraded.

To bring up the cluster out of mixed mode you have to raise cluster functional level. More on this in the follow up article…

Cluster Rolling Upgrade

In Microsoft TechNet there is a good description for the upgarade states:

the upgrade process for a single node is shown here:

The whole upgrade process is described in TechNet.

Conclusion

This new way to upgrade a cluster is really cool. You can upgrade a cluster with no downtime for your VMs.
While you are upgrading your cluster you have the full functionality of your cluster.
Now you just need to update the integration services in your VMs. And here is another cool feature upgrading integration services with windows update so there is now separate downtime for this too.

In an article of Aidan Finn he describes that Microsoft will support the mixed mode for 4 weeks. So you have to proceed your upgrade quick. But this time limit is not hard coded…it is just a support limit.

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