Recover from loss of controlfile in NOARCHIVELOG mode using RMAN

Here I am taking simple scenario to recover the controlfile. Following describes a scenario when my database is in NOARCHIVELOG mode. Database in oracle 10.2.0.1.0

SCENARIO: WHEN USED WITH DEFAULT RMAN CONFIGURATION SETTINGS.

Here only controlfile is lost, all the datafile and redo log files remain intact.
Following are the steps that can be taken:

1.RMAN> STARTUP MOUNT
2.RMAN> BACKUP DATABASE
3. RMAN> ALTER DATABASE OPEN;
4. delete controlfile.
5. RMAN> SHUTDOWN ABORT;
6. RMAN> STARTUP;
Database will not start. It starts in nomount state.
7. RMAN> RESTORE CONTROLFILE FROM AUTOBACKUP;
8. RMAN> ALTER DATABASE MOUNT;
9. RMAN> RESTORE DATABASE;
10.RMAN> RECOVER DATABASE ;
11.RMAN> ALTER DATABASE OPEN RESETLOGS;

And database will be recovered. Here SET DBID command is not needed because backup is located in flash recovery area. Controlfile autobackup default format is used.

SCENARIO: WHEN USED WITH non-DEFAULT RMAN CONFIGURATION SETTINGS.

I changed some of the default RMAN configuration settings. Now backup is not using flash recovery area. Also, controlfile autobackup is not using flash recovery area.

RMAN> SHOW ALL;

RMAN configuration parameters are:
CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default
CONFIGURE BACKUP OPTIMIZATION ON;
CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default
CONFIGURE CONTROLFILE AUTOBACKUP ON;
CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '/usr/lib/oracle/xe/backup/cf_%F';
CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default
CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default
CONFIGURE CHANNEL DEVICE TYPE DISK MAXPIECESIZE 400 M FORMAT '/usr/lib/oracle/xe/backup/df_%U';
CONFIGURE MAXSETSIZE TO UNLIMITED; # default
CONFIGURE ENCRYPTION FOR DATABASE OFF; # default
CONFIGURE ENCRYPTION ALGORITHM 'AES128'; # default
CONFIGURE ARCHIVELOG DELETION POLICY TO NONE; # default
CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/usr/lib/oracle/xe/app/oracle/product/10.2.0/server/dbs/snapcf_XE.f'; # default


Now follow these steps:

1.RMAN> STARTUP MOUNT
2.RMAN> BACKUP DATABASE
3. RMAN> ALTER DATABASE OPEN;
4. delete controlfile.
5. RMAN> SHUTDOWN ABORT;
6. RMAN> STARTUP;
Database will not start. It starts in nomount state.
7. RMAN> SET DBID=
8. RMAN> SET CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '/usr/lib/oracle/xe/backup/cf_%F';
9. RMAN> RESTORE CONTROLFILE FROM AUTOBACKUP;
10. RMAN> ALTER DATABASE MOUNT;
11. RMAN> RESTORE DATABASE;
12.RMAN> RECOVER DATABASE ;
13.RMAN> ALTER DATABASE OPEN RESETLOGS;

Note: If all the redo logs since the last database exist, then you can skip RESTORE DATABASE statement in both the above cases.