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By William Sescu Have you ever noticed a DB_UNKNOWN directory in your ASM structure? It usually happens in combination with spfile creation in ASM, or with RMAN spfile restores to ASM. The correct location is +DATA/<SID>/PARAMETERFILE/SPFILE.<#>.<#>, and an ASM alias from +DATA/<SID>/ pointing to it. But sometimes, the spfile ends up in +DATA/DB_UNKNOWN/PARAMETERFILE/SPFILE.<#>.<#> Technically no issue. The spfile in the DB_UNKNOWN directory is perfectly ok and can be used. However, you might need to adjust…

By William Sescu Do you see any differences between these two RMAN SHOW commands? RMAN> SHOW CONTROLFILE AUTOBACKUP FORMAT; RMAN configuration parameters for database with db_unique_name OCM121 are: CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO ‘%F'; # default and RMAN> SHOW CONTROLFILE AUTOBACKUP FORMAT; RMAN configuration parameters for database with db_unique_name OCM121 are: CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO ‘%F';   They are the same, except that the first output…

By William Sescu By default, automatic control file backups are disabled (even with 12c), maybe for performance reasons. RMAN> SHOW CONTROLFILE AUTOBACKUP; RMAN configuration parameters for database with db_unique_name OCM121 are: CONFIGURE CONTROLFILE AUTOBACKUP OFF; # default And also good to know, the autobackup after structural changes does not occur for databases in NOARCHIVELOG mode. So, if your database is running in NOARCHIVELOG mode, you will never see any impact, independent of controlfile autobackup is…

By William Sescu Not too often, but sometimes you might run into a situation when you lose everything, your DB Files, your Controlfiles and even your spfile. In situations like that, you need to restore first your spfile, then your controlfile and then the rest. For restoring the spfile, RMAN has a chicken/egg issue. To be able to restore the spfile, RMAN needs at least a running instance, but how do we start the instance…

By William Sescu RMAN persistent settings can be managed in two different ways. Via the RMAN interface – e.g. RMAN> CONFIGURE BACKUP OPTIMIZATION ON; Via SQL – e.g. VARIABLE RECNO NUMBER; EXECUTE :RECNO := SYS.DBMS_BACKUP_RESTORE.SETCONFIG(‘BACKUP OPTIMIZATION’,’ON’); There are several scenarios when it might be helpful to use the SQL way. I will show 3 of them: Automation Reset to default Rebuilding the RMAN persistent settings after losing all controlfiles (no catalog) Let’s take a look…