Controlfiles - Multiplexing

When the instance is running use the following command for changing the controlfiles and then bounce. Before copying one control file to another location (for multiplexing) the database should be Shutdown

SQL> alter system set control_files='/oracle/data02/SDW/ora_control02.ctl' scope=spfile;
System altered.
SQL> startup force
ORACLE instance started.

When more than one file is mentioned, error encountered

SQL> alter system set control_files='/oracle/data02/SDW/ora_control02.ctl,/oracle/data01/SDW/ora_control01.ctl' scope=spfile;
ORA-00205: error in identifying control file, check alert log for more info

The cause was wrong statement - notice the comma outside the single quotes.

SQL> alter system set
control_files='/oracle/data02/SDW/ora_control02.ctl','/oracle/data01/SDW/ora_control01.ctl' scope=spfile;

If at all, a recreation of lost control file is required, the following details are essential.

SELECT NAME FROM V$DATAFILE
UNION ALL
SELECT MEMBER FROM V$LOGFILE
UNION ALL
SELECT NAME FROM V$CONTROLFILE;