Restore controlfile from autobackup on oracle database

Lost or corrupted controlfile can be restored from autobackup provided that controlfile autobackup is configured using RMAN ‘CONFIGURE’ command:

RMAN>  CONFIGURE CONTROLFILE AUTOBACKUP ON

Once autobackup is configured, the assumption is that  backup of controlfile is taken after configuration.

Here are the steps to restore the control file:

---Try to connect to the database with the missing controlfile
SQL> conn sys/orcl@to_primary as sysdba;
Connected to an idle instance.
SQL> startup;
ORACLE instance started.
 Total System Global Area 2499805184 bytes
Fixed Size                  8749920 bytes
Variable Size             687869088 bytes
Database Buffers         1795162112 bytes
Redo Buffers                8024064 bytes
ORA-00205: error in identifying control file, check alert log for more info

---Connect to RMAN and perform the restore and recover tasks
SQL> $ rman target "'/ as sysbackup '"
 Recovery Manager: Release 12.2.0.1.0 - Production on Sat Feb 12 23:18:31 2022
 Copyright (c) 1982, 2017, Oracle and/or its affiliates.  All rights reserved.
 connected to target database: ORCL (not mounted)
    
---Start in no mount state because there is no controlfile.
RMAN> startup nomount;  ---- Starts the background processes and allocates memory, doesn't read control files
 database is already started

---Restore the controlfile from autobackup
RMAN> restore controlfile from autobackup;
 Starting restore at 12-FEB-22
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=379 device type=DISK
 recovery area destination: D:\app\Admin\virtual\fast_recovery_area\orcl
database name (or database unique name) used for search: PRIMARY
channel ORA_DISK_1: AUTOBACKUP D:\APP\ADMIN\VIRTUAL\FAST_RECOVERY_AREA\ORCL\PRIMARY\AUTOBACKUP\2022_02_12\O1_MF_S_1096499657_K0J58W84_.BKP found in the recovery area
AUTOBACKUP search with format "%F" not attempted because DBID was not set
channel ORA_DISK_1: restoring control file from AUTOBACKUP D:\APP\ADMIN\VIRTUAL\FAST_RECOVERY_AREA\ORCL\PRIMARY\AUTOBACKUP\2022_02_12\O1_MF_S_1096499657_K0J58W84_.BKP
channel ORA_DISK_1: control file restore from AUTOBACKUP complete
output file name=D:\APP\ADMIN\VIRTUAL\ORADATA\ORCL\CONTROL01.CTL
output file name=D:\APP\ADMIN\VIRTUAL\FAST_RECOVERY_AREA\ORCL\CONTROL02.CTL
Finished restore at 12-FEB-22

---Now the controlfile is available and lets start the database in mount state--
RMAN> alter database mount;
 Statement processed
released channel: ORA_DISK_1

---Recover the database
RMAN> recover database;
 Starting recover at 12-FEB-22
Starting implicit crosscheck backup at 12-FEB-22
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=379 device type=DISK
Crosschecked 12 objects
Finished implicit crosscheck backup at 12-FEB-22
 Starting implicit crosscheck copy at 12-FEB-22
using channel ORA_DISK_1
Crosschecked 2 objects
Finished implicit crosscheck copy at 12-FEB-22
 searching for all files in the recovery area
cataloging files...
cataloging done
 List of Cataloged Files
=======================
File Name: D:\APP\ADMIN\VIRTUAL\FAST_RECOVERY_AREA\ORCL\PRIMARY\AUTOBACKUP\2022_02_12\O1_MF_S_1096499657_K0J58W84_.BKP
 using channel ORA_DISK_1
 starting media recovery
 archived log for thread 1 with sequence 2 is already on disk as file D:\APP\ADMIN\VIRTUAL\ORADATA\ORCL\REDO02.LOG
archived log file name=D:\APP\ADMIN\VIRTUAL\ORADATA\ORCL\REDO02.LOG thread=1 sequence=2
media recovery complete, elapsed time: 00:00:01
Finished recover at 12-FEB-22

---Open the database --
RMAN> alter database open resetlogs;
 Statement processed
RMAN> exit
 Recovery Manager complete.

 ---Finally, you will be connected to your database without an error--
SQL> conn sys/orcl@to_primary as sysdba;
Connected.
SQL>