Cluster-Aware Updating is a neat little feature added by Microsoft - it easens the burden of system administration by giving the administrator some extra-comfort. Namely, it can speed maintenance up by quite a bit by automatically applying a sequence of system updates to every node in a row (i.e. a cluster).

This feature is also quite easy to add to your existing cluster - just pick the Cluster-Aware Updating link sitting inside your Failover Cluster Manager and follow the wizard.

However, should you encounter any problems with the creation of the AD account, please try prestaging the CAU AD account so that users other than Domain Admins can add the account ("Everyone" should work):

That should do it - your cluster should be ready for self-updating procedure...