patching an MSCS SQL cluster
We've been having issues patching Microsoft SQL clusters (SQL 2008/2008R2) using patch management. What I have been doing is to make sure the patches are downloaded to the machines. I don't have the machines setup to automatically patch. I've scripted out the failover of the cluster and the patching of the machine with aexpatchutil.exe and use jobs and tasks to launch the script. When it runs the script works appropriately and the resources failover to the passive node and then patching begins. The problem we are having is that the SQL service packs are not installing on the machines. Other Operating System based patches are installing fine. Our dba's looked at SQL and the SQL tools are being patched but SQL itself is not. There are no errors messages indicating why it's failing to install. The account that is used to launch the script is a administrator of the box and has administrative access to SQL. Additionally, we've added the system accounts of the machines to have administrative access.
How do other people patch SQL clusters with this tool?