If you used DBCA to create a preconfigured image of your single-instance database as described in "Use DBCA to Create an Image of the Single-Instance Database" then perform the following steps to complete the conversion to an Oracle RAC database:
Start DBCA from the initial node. Select the names of the nodes to include as part of your cluster database. On the Template Selection page, select the preconfigured template that you created. Enter the database name and respond to the remaining DBCA prompts.
Specify the shared storage ___location for the Oracle Database data files. To use raw devices for the data files, you cannot use DBCA. Instead, follow the steps documented in "Manual Conversion Procedure"
After creating the Oracle RAC database, DBCA displays the Password Management page on which you must change the passwords for the database users who have SYSDBA and SYSOPER privileges. When DBCA exits, the conversion process is complete.