Since the database cannot be opened before the damaged online redo log is recreated, the DBA starts the database in the mount mode. The DBA issues the startup open command to mount the database(1) and gets the error message indicating what is wrong with the database. From the error message, the DBA knows that the online log #3 is corrupted (2)
The DBA queries the data dictionary view V$LOGFILE to find the location to create the damaged redo log file(3). The result shows the location (4).
Since there are more than two online redo logs, the DBA drops the corrupted online redo log (5) and recreates it (6) Now the database is ready to be opened (7).