11G R2 RAC ORA-12514 error

Problem

Gettting OA-12514 from client after fresh installation of 11gR2 RAC on OEL5.

Cause

Service name mismatch between listener and tnsnames.ora.

Solution

After investigation lsnrctl services output for listeners. Understood that while the the listener contains fully qualified domain name as service name, tnsnames.ora does not. Changing the client's tnsnames entry as follows solved the problem.

from:

MYTESTDB=(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)
(HOST=mytestdb-scan.mycompany.com)(PORT=1521))
(CONNECT_DATA=(SERVICE_NAME=mytestdb)))

to:

MYTESTDB=(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)
(HOST=mytestdb-scan.mycompany.com)(PORT=1521))
(CONNECT_DATA=(SERVICE_NAME=mytestdb.mycompany.com)))