In my continued efforts over the past few weeks putting together a Windows Server 2012 Hyper-V Cluster, I recently discovered a nifty new feature to Windows Server 2012’s Failover Clustering – Cluster Aware Updating.

This feature is going to save a lot of SysAdmin time when it comes to patching your Failover Cluster nodes, the only real interaction required is simply to setup the schedule. Cluster Aware Updating will fully automate patching your cluster nodes one-by-one without impact to your cluster applications or roles.

Initial setup of CAU requires that you select a “Co-ordinator”, and this basically does what it says on the tin. The Co-ordinator manages and monitors the patching tasks across the nodes in the cluster. This role can be enabled within the cluster or outside.

The CAU Co-ordinator will perform the following steps -:

• Download Updates to each node
• Selects the node with the fewest applications/roles first (although you can specify a specific order during setup)
• Initiates a Node Drain, i.e. moves the applications/roles off the node to other nodes in the cluster
• Sets the node into Maintenance Mode
• Installs the downloaded updates
• Restarts the node if required
• Verifies the installed updates
• Brings the node out of Maintenance Mode
• Moves the applications/roles that were previously moved off the node back again
• Repeat the above steps for the next node in the cluster

As you can see performing those steps manually is a very time consuming task, especially for large clusters with many applications/roles. The most time consuming and tedious part being the application/role migrations and ensuring you move the same roles back again afterwards.

CAU can install updates from a number of sources including:

• Windows/Microsoft Update
• Windows Server Update Services (WSUS)
• Hotfixes or Cumulative Updates not released via Windows/MS Update (setup a file share)
• 3rd Party Driver and Firmware updates (setup file share)

So not only does CAU save you time but it ensures that your cluster nodes are all at the same update levels too which of course is desirable at all times.

One thing I did notice was the SCOM agent on the cluster nodes got stuck in Maintenance Mode. I had to fix this by putting the nodes into Maintenance Mode via the SCOM console for 10 minutes, after which the nodes were successfully monitored again.

This is certainly one of my favourite additions to the Server 2012 feature set so far. If you have a Server 2012 cluster then enable this feature!

 

James