ORA-00205: error in identifying control file, check alert log for more info

 In Oracle when you see ORA-00205: error in identifying control file, check alert log for more info

# It means your control file is missing either 1 or all as per control_files initialization parameter.

In this case we need to restore and recover the database using control file backup, lets see how we can do it via RMAN utility :

[oracle@node2 ~]$ rman target/

Recovery Manager: Release 21.0.0.0.0 - Production on Mon May 22 23:20:11 2023

Version 21.3.0.0.0

Copyright (c) 1982, 2021, Oracle and/or its affiliates.  All rights reserved.

connected to target database: ORCL (not mounted)

RMAN> restore controlfile from '/u01/app/oracle/fast_recovery_area/ORCL/autobackup/2023_05_22/o1_mf_s_1137539677_l6qbj5wn_.bkp';

Starting restore at 22-MAY-23

using target database control file instead of recovery catalog

allocated channel: ORA_DISK_1

channel ORA_DISK_1: SID=422 device type=DISK

channel ORA_DISK_1: restoring control file

channel ORA_DISK_1: restore complete, elapsed time: 00:00:01

output file name=/u01/app/oracle/oradata/ORCL/control01.ctl

output file name=/u01/app/oracle/fast_recovery_area/ORCL/control02.ctl

Finished restore at 22-MAY-23

RMAN> alter database mount;

released channel: ORA_DISK_1

Statement processed

RMAN> recover database ;

Starting recover at 22-MAY-23

Starting implicit crosscheck backup at 22-MAY-23

allocated channel: ORA_DISK_1

channel ORA_DISK_1: SID=430 device type=DISK

Crosschecked 8 objects

Finished implicit crosscheck backup at 22-MAY-23

Starting implicit crosscheck copy at 22-MAY-23

using channel ORA_DISK_1

Finished implicit crosscheck copy at 22-MAY-23

searching for all files in the recovery area

cataloging files...

cataloging done

List of Cataloged Files

=======================

File Name: /u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_5_l6qbqvoj_.arc

File Name: /u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_6_l6qbqz3l_.arc

File Name: /u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_7_l6qbr0py_.arc

File Name: /u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_8_l6qbr3po_.arc

File Name: /u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_9_l6qbr6qv_.arc

File Name: /u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_10_l6qbr9qt_.arc

File Name: /u01/app/oracle/fast_recovery_area/ORCL/autobackup/2023_05_22/o1_mf_s_1137539677_l6qbj5wn_.bkp

using channel ORA_DISK_1

starting media recovery

archived log for thread 1 with sequence 5 is already on disk as file /u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_5_l6qbqvoj_.arc

archived log for thread 1 with sequence 6 is already on disk as file /u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_6_l6qbqz3l_.arc

archived log for thread 1 with sequence 7 is already on disk as file /u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_7_l6qbr0py_.arc

archived log for thread 1 with sequence 8 is already on disk as file /u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_8_l6qbr3po_.arc

archived log for thread 1 with sequence 9 is already on disk as file /u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_9_l6qbr6qv_.arc

archived log for thread 1 with sequence 10 is already on disk as file /u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_10_l6qbr9qt_.arc

archived log for thread 1 with sequence 11 is already on disk as file /u01/app/oracle/oradata/ORCL/redo02.log

archived log file name=/u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_5_l6qbqvoj_.arc thread=1 sequence=5

archived log file name=/u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_6_l6qbqz3l_.arc thread=1 sequence=6

archived log file name=/u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_7_l6qbr0py_.arc thread=1 sequence=7

archived log file name=/u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_8_l6qbr3po_.arc thread=1 sequence=8

archived log file name=/u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_9_l6qbr6qv_.arc thread=1 sequence=9

archived log file name=/u01/app/oracle/fast_recovery_area/ORCL/archivelog/2023_05_22/o1_mf_1_10_l6qbr9qt_.arc thread=1 sequence=10

archived log file name=/u01/app/oracle/oradata/ORCL/redo02.log thread=1 sequence=11

media recovery complete, elapsed time: 00:00:01

Finished recover at 22-MAY-23

RMAN> exit

Recovery Manager complete.

[oracle@node2 ~]$ sqlplus / as sysdba

SQL*Plus: Release 21.0.0.0.0 - Production on Mon May 22 23:20:51 2023

Version 21.3.0.0.0

Copyright (c) 1982, 2021, Oracle.  All rights reserved.

Connected to:

Oracle Database 21c Enterprise Edition Release 21.0.0.0.0 - Production

Version 21.3.0.0.0

SQL> alter database open resetlogs;

Database altered.

SQL> show pdbs

    CON_ID CON_NAME                       OPEN MODE  RESTRICTED

---------- ------------------------------ ---------- ----------

         2 PDB$SEED                       READ ONLY  NO

         3 PDB1                           READ WRITE NO

SQL> select name,open_mode from v$database;

NAME      OPEN_MODE

--------- --------------------

ORCL      READ WRITE

# Thats it recovery is now completed and your database is available now.