Before you convert a single-instance database to an Oracle RAC database, ensure that the following conditions are met for each cluster node that you intend to make an Oracle RAC database node:
Oracle Clusterware 12c is installed, configured, and running.
Oracle RAC 12c software is installed.
The Oracle software has the Oracle RAC option enabled.
Shared storage, either Oracle Cluster File System or Oracle ASM, is available and accessible from all nodes.
User equivalence exists for the oracle account, or the user account used to install the Oracle software.
If you intend to use Oracle Enterprise Manager, then the Oracle Management Agent on each node is configured and running, and is configured with cluster and host information.
You have backed up your existing database.
Note:
You must use clustered Oracle ASM instances for Oracle RAC databases.