Yesterday I was patching a cluster, currently running SQL Server 2008 R2 SP1 on a Windows 2008 R2 cluster having three nodes running three SQL server instances. I have to upgrade them to SQL Server 2008 R2 SP2 CU4.
I start with the passive node which was 06 in this case. I start the SP2 installer, run it as administrator, run rule check, agree to terms and conditions and come to the page where we select instances to patch/upgrade/service. What I find is blank. No instance shows up to patch.
I see the same on 05 too but all shows up fine on 07.
Surprisingly, entire cluster is working fine and I am able failover from one Node to another with no issues. I guess its due to some corruption in registry keys.
Solution, I run add node to cluster, from SQL installer on 06, three times to add all three instances. Run SP2 install to upgrade all three instances at one go. Run CU4 installer and upgrade all instances to CU4 on 06. Failover all instances to 06. Run SP2, CU4 upgrade on 07. Move couple of instances to 07. So now I have three instances spread over 06 and 07. Then start working on 05. Start with add node to cluster, thrice, then SP2 and then CU4. It remains a passive node.