Database and Listener startup checks
From Oracle FAQ
The following procedure explains the process to check if your databases and listeners are up and running. It is important to have a procedure as DBA's frequently start the environment, just to later found that users were unable to work.
- Find the databases that are supposed to be up and running from the /etc/oratab or /var/opt/oracle/oratab file. Look for entries that are suffixed by a "Y".
- Check if the database background processes are up and running
$ ps -ef | grep smon
- Change the environment and connect to each of these databases to ensure they are open
. oraenv sqlplus username/password
- Find all the listeners in the listener.ora file. This file is located in either /etc, /var/opt/oracle or $ORACLE HOME/network/admin directories
- Make sure each of them is running (lsnrctl status LISTENER_NAME)
- Connect to all databases via their listeners to ensure that the listeners are functioning (sqlplus username/passwprd@dbdescriptor). Connecting to the db via their listeners should be done from a node different than the one on which the listener is running to make 100% sure that there is remote connectivity.
- Check the database alert log files: sometimes a database may be up and running, but the alert log reports critical errors.
- Call users and get them to test the application.
- Most machines only has one listener BUT, please do not accept that they all have only one listener. When in doubt please read the manuals or ask somebody.
- It is also helpful to write some scripts to help you check that everything is up and running. Example scripts could be obtained from the scripts section of this web site.