This procedure assumes that one of the control files specified in the CONTROL_FILES parameter is inaccessible due to a permanent media failure, and you have a multiplexed copy of the control file.
With the instance shut down, use an operating system command to copy the current copy of the control file to a new, accessible location:
% cp /u01/oracle/prod/control01.ctl /u04/oracle/prod/control03.ctl
Edit the CONTROL_FILES parameter in the initialization parameter file to replace the bad location with the new location:
CONTROL_FILES = (/u01/oracle/prod/control01.ctl,
/u02/oracle/prod/control02.ctl,
/u04/oracle/prod/control03.ctl)
Start SQL*Plus and open the database:
SQL> STARTUP