I think that moving rc scripts etc. is really complicating things for no reason.
Pre-patching highly recommended, but not required, steps:
1. Evacuate the first system in the cluster. This will temporarily freeze it and fail all of its service groups over to the second system. This is to confirm that all of the groups will still fail over to/run on the second system.
2. Reboot, and then unfreeze the first system (since second system never loses cluster state, the freeze remains in effect). Evacuate the second system in the cluster. Again, you are confirming that your service groups will run on either system in the cluster.
3. Reboot, and then unfreeze the second system. Evacuate the first system in the cluster.
This is just best practice - you want to find out BEFORE you do any patching etc. that your applications are not capable of failover (technically an hagrp -switch in this case), have undergone some type of configuration drift, etc.
Required steps:
1. Persistently freeze at least the first system in the cluster (or both).
2. Dump/close the cluster configuration.
3. Offline whichever service groups (all?) that you want. A system freeze will not affect this.
4. Patch/reboot/etc. as desired. I recommend doing all of this on one node, unfreezing and confirming applications come up on that node, then doing the other node - but you can do both at once if your confidence is high or your application requires it.
Good luck.
C