In active database duplication, RMAN connects as TARGET to the source database instance and as AUXILIARY to the auxiliary instance. RMAN then manages the copying of the database to the auxiliary instance over the network. No backups of the source database are required.
RMAN can transfer the files required for active database duplication as image copies or backup sets.
Note:
Performing active database duplication using backup sets is available starting with Oracle Database 12c Release 1 (12.1).
Figure 25-2 illustrates active database duplication.
Figure 25-2 Active Database Duplication
[size=0.75em]Description of "Figure 25-2 Active Database Duplication"
When active database duplication is performed using image copies, after RMAN establishes a connection with the source database, the source database transfers the required database files to the auxiliary database. Using image copies may require additional resources on the source database. This method is referred to as the push-based method of active database duplication.
When RMAN performs active database duplication using backup sets, a connection is established with the source database and the auxiliary database. The auxiliary database then connects to the source database through Oracle Net Services and retrieves the required database files from the source database. This method of active database duplication is also to as the pull-based method.
Using backup sets for active database duplication provides certain advantages. RMAN can employ unused block compression while creating backups, thus reducing the size of backups that are transported over the network. Backup sets can be created in parallel on the source database by using multisection backups. You can also encrypt backup sets created on the source database.