Hopefully, you have taken the time to practice several different types of recovery scenarios before having to do this for real in a production situation. This can be extremely nerve wracking. So take some time to settle down before starting, as you will need to think clearly. Don't leave the scene of the crime until things are normal, even if it turns out badly. Here are some generalized steps on how to proceed when the database goes down:
Determine what is actually wrong before continuing
Error messages don't always point to exactly what is wrong. They can be vague or general unless some sort of tracing is enabled. First, start with the database alert log and check for the existence of core dumps. Oracle has designed an RMAN-directed Failure Adviser that can be used in conjunction with manual procedures, but the adviser won't replace any of the steps in this list.
Run the
recovery_status.sqlscript provided for this chapter. That might help...
