Hello,
The database upgrade itself is not that much different in a cluster environment than in a "classical" set up.
You usually have to stop the SAP application servers ressources, and stop the monitoring of the database ressources in order not to have the database switched during the oracle upgrade.
You then perform the upgrade in a classical way.
That said, due to the cluster, you have to take some extra care as the DB version upgrade can have an impact on the cluster software requirements, and therefore on the OS level ( mainly patches ) requirements. In order for the cluster to work properly with your new DB version, it is somtime required to apply some patches on the cluster software. These may also need some OS patches to be applied. This has to be looked at.
Could you please post your cluster ressources layout and your clustered FS layout also ?
Thx and Best regards,
S.SOUMAH.