Recovery Manager Restore and Recovery Techniques - Oracle 10g/11g Data and Database Management Utilities - page 137

In the following scenario it was not needed to restart the database. It was enough
to simply create a new temporary datafile ( G ) and get rid of the lost datafile
definition ( H ).
Loss of a critical datafile
The critical datafiles must be online in order for the oracle instance to be able to open
the database. If a critical datafile is lost then a recovery operation must be performed
so the database can be opened.
When a critical database file is lost, the procedure to bring the database back to
business is as follows:
1. Try to open the database, the procedure will stop the database at the mount
point and the error message will show the missing datafile or datafiles.
2. Verify at the V$RECOVER_FILE how many other datafiles are missing besides
the one reported in the previous error.
3. Issue the restore command. This will restore the correct datafile from the
backup media.
4. As the database won't allow the datafile to be set offline a recover operation
must take place.