Resolving Problems in Mixed-Database Environments in a 11gR2 Clusterware
Oracle 11.2 fully supports continuing to use non-11.2 databases on a cluster that has been upgraded to 11.2. However, you should be aware that the Oracle 11.2.0.1 base release contained a number of problems that could affect users with a 10.2 database. Known problem with brand new installations of Grid Infrastructure 11.2 and pre-11.2 RDBMS instances is related to node pinning. During the upgrade, the nodes containing 10.2 RDBMS software will be pinned, allowing pre-11.2 databases to run on them. Important aspect is with Non-upgraded clusters are not automatically pinned, which causes problems with emca and dbca when executed from the pre-11.2 Oracle homes. You should use the utilities from the $GRID_HOME to manage resources provided by the same Oracle home. Similarly, when managing pre-11.2 resources, you can use the commands from their respective homes. This is a golden rule to remember You can find more information about problems with 10.2 databases and 11.2 Grid Infras...
