A full system backup should be performed before all major actions such as a system upgrade. The backup is not required as part of the actual upgrade (as was needed for the R11.0.4.3 to R11.1 GA upgrade process. However is an absolutely necessary provision in order to recover should issues occur in the R11.1 SP2upgrade process.
Process Summary
1.Having fully verified the operation of all services at R11.0.4.5, backup the R11.0.4.5 servers. See Creating a Back Up.