Review some of the best practices for using multiple Oracle instances in a VCS environment:

• For each SID to be configured, create Linux accounts with DBA privileges.

• Make sure that each Oracle instance has a separate disk group and is configured as a separate service group.

• Define the system parameters such that the allocation of semaphore and shared memory is appropriate on all systems.

• Use a dedicated set of binaries for each Oracle instance, even if each instance uses the same Oracle version.

• If your configuration uses the same Oracle version for all instances, install a version on the root disk or preferably on a secondary disk. Locate the pfiles in the default location and define several listener processes to ensure clean failover.

• If your configuration has different versions of Oracle, create a separate $ORACLE_HOME for each Oracle version.

• Follow the Optimal Flexible Architecture (OFA) standard (/uxx/<SID>). In cluster configurations, you could adapt the standard to make it more application-specific. For example, /app/uxx/<SID>.

• Listeners accompanying different versions of Oracle may not be backward-compatible. So, if you want to create a single listener.ora file, you must verify that the listener supports the other versions of Oracle in the cluster. You must also create a separate Envfile for each version of Oracle.

• Make sure that each listener listens to a different virtual address. Also, assign different names to listeners and make sure that they do not listen to the same port.

• The pfiles must be coordinated between systems. For the same instance of a database, ensure that the pfiles referenced are identical across the nodes.