Decide on a Naming Convention to Use for Your Oracle RAC Database
Review this information for naming conventions for Oracle RAC database.
The global database name can be up to 30 characters in length, and must begin with an alphabetic character. The domain portion of the global database name can be no more than 128 characters and can contain only alphabetic and numeric characters, and the period (.) character.
The maximum number of characters you can use for the SID prefix is 8 characters. DBCA uses the SID prefix to generate a unique value for the variable ORACLE_SID
for each instance. The SID prefix must begin with an alphabetic character.