NOARCHIVELOG DATABASE – WITHOUT BACKUP – REDO MEMBERS ARE NOT MULTIPLEXED and somehow one day the DISK WHICH HAS CURRENT REDO CRASHES..
Yesterday one of my best friends called me because of the above situation. Since he is a developer minded expert it was ok for me to help him, if he had a little dba profile I would never answer his calls :)
This one is of the worst situations you may experience, it is similar to making sex with someone you already know having hiv virus without protection, but with Oracle there is always hope! Below is the support message of Oracle, it is like a doctor bringing someone back to life after some minutes of death on the operation table;
So please forget tuning, development etc. and immediately check this post for the basic backup and recovery needs like ARCIVELOG MODE-MULTIPLEXING REDO and CONTROL FILES-RMAN BACKUP, even it may be your local XE test database!