The scope of this blog will be to show how to create a primary role database based on a backup of a standby database on 12cR2.

Step1: We are assuming that an auxiliary instance has been created and started in nomount mode.

rman target /
restore primary controlfile from 'backup_location_directory/control_.bkp';

By specifying “restore primary” , will modify the flag into the controlfile, and will mount a primary role instance instead of a standby one.

Step2: Once mounted the instance, we will restore the backup of the standby database.

catalog start with 'backup_location_directory';
restore database;
alter database flashback off;
recover database 

If in the pfile used to start the instance, you specified the recovery destination and size parameters it will try to enable the flashback.
The flashback enable , before during the recovery is not allowed, so we will deactivate for the moment.

Step3: Restore/recover completed successfully, we will try to open the database, but got some errors:

alter database open :

ORA-03113: end-of-file on communication channel
Process ID: 2588
Session ID: 1705 Serial number: 5

Step4: Fix the errors and try to open the database:

--normal redo log groups
alter database clear unarchived logfile group YYY;

--standby redo log groups
alter database clear unarchived logfile group ZZZ;
alter database drop logfile group ZZZ;

Is not enough. Looking on the database alert log file we can see :

LGWR: Primary database is in MAXIMUM AVAILABILITY mode 
LGWR: Destination LOG_ARCHIVE_DEST_2 is not serviced by LGWR 
LGWR: Destination LOG_ARCHIVE_DEST_1 is not serviced by LGWR 

Errors in file /<TRACE_DESTINATION>_lgwr_1827.trc: 
ORA-16072: a minimum of one standby database destination is required 
LGWR: terminating instance due to error 16072 
Instance terminated by LGWR, pid = 1827

Step5: Complete the opening procedure:

alter system set log_archive_dest_1='LOCATION=USE_DB_RECOVERY_FILE_DEST';
alter database set standby database to maximize performance;

SQL> select name,open_mode,protection_mode from v$database;

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

SQL> alter database flashback on;

Database altered.

SQL> alter database open;

Database altered.

SQL> select name,db_unique_name,database_role from v$database;

--------- ------------------------------ ----------------
NAME      NAME_UNIQUE                    PRIMARY