I am running Oracle 11 on Linux Ubuntu 12.10. The database has been running well for a long time. Now, suddenly, when I or one of my applications tries to connect to the database, the database replies with ORA-01034 and ORA-27101. I've tried most of the available suggestions, and either they don't work (run DBstart which doesn't exist on my machine) or I lack sufficient permissions (SQLplus / as SYSDBA). Can you help? Thanks very much!