I'm going to upgrade our NetWare 6.0 SP5 cluster to NW6.5SP6 next week.
Anything I should be extra careful about? Any caveats?

The cluster has two nodes that are connected to a HP MSA1000 SAN.

I'm supposed to start the upgrade using the server GUI, am I correct?

I'm thinking to first rem out the backup agent and antivirus from the
autoexec.ncf, then reboot, then run the upgrade.