Before starting DBCA to configure an Oracle RAC database, you must have installed Oracle Grid Infrastructure for a cluster, and you must have configured shared storage areas for Oracle RAC files.
Storage administration tasks require the
SYSASM system privileges, which are granted to members of the
OSASM operating system group. This group may not be the same as the
OSDBA group, whose members are granted the
SYSDBA system privileges.
See Oracle Grid Infrastructure Installation Guide for your platform for more information about shared storage configuration requirements.