12c Database : RMAN Enhancement : Duplicate from Active Database Enhancements

The ACTIVE DUPLICATE DATABASE option in 11g clone the source database by coping the full image of the data files to the auxiliary instance location through the network. This procedure doesn’t not required any pre backup existence to clone the database. However, in Oracle 12c, when ACTIVE DUPLICATE DATABASE is initiated, instead of sending the full image copy of the data files, RMAN first takes the backup of data files into backupsets, and these backups are transmit to the auxiliary location and will be restored/recovered subsequently. This functionality will surely reduce the overall impact on the source instance and also help fastening the cloning procedure. You have the flexibility to use backup compression, encryption option with this feature.

         RMAN> DUPLICATE TARGET DATABASE to stby2
                 FROM ACTIVE DATABASE
                 SECTION SIZE 500M
                 USING COMPRESSED BACKUPSETS;

In the previous releases, the cloned database will be opened automatically upon the process completion. The additional NOOPEN clause in 12c, will prevent opening database immediately after the cloning process completion. Therefore, the database will remain in MOUNT state after the procedure and you will have to manually open the database. This will be a good option to use in the following scenario: When the cloned database required additional settings, like, flash back or incremental backup settings. To avoid any startup problems To adjust the initialization parameters If this database is used for upgrade purpose, you can just start the db in UPGRADE mode to proceed with the upgrade. Here is the example how to use NOOPEN clause:

                 RMAN> DUPLICATE TARGET DATABASE to stby3
                          FROM ACTIVE DATABASE
                          SECTION SIZE 500M
                          USING COMPRESSED BACKUPSETS
                          NOOPEN;