Troubleshooting the RCU

If the RCU fails to connect to the Oracle database, follow the steps below.
  1. Stop the listener.
    /app/oracle/product/11.2.0/db_home1/bin/lsnrctl stop LISTENER
  2. As root, edit the /etc/hosts file and remove your <server name> in the 127.0.0.1 and ::1 line.
    127.0.0.1   localhost.localdomain  localhost.localdomain  localhost4  localhost4.localdomain4  localhost  centosTemplate  <server_name>
    ::1         localhost.localdomain  localhost.localdomain  localhost6  localhost6.localdomain6  localhost  centosTemplate  <server_name>
  3. Restart the listener.
    /app/oracle/product/11.2.0/db_home1/bin/lsnrctl start LISTENER
  4. Double check the status.
    /app/oracle/product/11.2.0/db_home1/bin/lsnrctl status LISTENER
    Look for the server name after the HOST parameter.
    Listening Endpoints Summary...
       (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521)))  
       (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=<server_name>)(PORT=1521)))
  5. Try to connect to the Oracle database again.