In this case, control02.ctl was deleted intentionally in order to demonstrate below oracle error.

SQL> shutdown immediate;
ORA-00210: cannot open the specified control file
ORA-00202: control file: '/u01/app/oracle/oradata/RTS/control02.ctl'
ORA-27041: unable to open file
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3

Solution:

Change control_files parameter to existing/available control file, i.e. control01.ctl:

SQL> alter system set control_files='/u01/app/oracle/oradata/RTS/control01.ctl' scope=spfile;
System altered.

Shutdown abort your database, because oracle won’t allow database to be shutdown with normal or immediate option.

SQL> shut abort;
ORACLE instance shut down.

SQL> startup
ORACLE instance started.
Total System Global Area 755769344 bytes
Fixed Size 2217184 bytes
Variable Size 478153504 bytes
Database Buffers 272629760 bytes
Redo Buffers 2768896 bytes
Database mounted.
Database opened.

Now your database is opened with existing control file, and It is highly recommended to run your Oracle database with multiple control files(called control file multiplexing) in order to reduce the risk of losing control file due to corruption, accidental removal or any possible worst. How to multiplex Oracle control file?

Thanks, Stay Tune. 🙂