Here is the link to the Administrator guide for RMAN. https://support.emc.com/docu86478_Oracle_RMAN_Agent_4.5_Administration_Guide.pdf?language=en_US&sour... If you look on page 16 it list the following:
The Oracle RMAN agent enables database servers to communicate with Data Domain systems in an optimized way, without the need to use a backup application.
In earlier versions of the product, the Oracle RMAN agent was known as Data Domain Boost (DD Boost) for Oracle Recovery Manager (RMAN) or the RMAN plug-in. In version 4.0, the product name changed to Oracle RMAN agent.
The use of the Oracle RMAN agent improves performance while reducing the amount of data that is transferred over the LAN. In the context of Oracle RMAN, the software has two components: l An RMAN agent that you install on each database server. This RMAN agent includes the DD Boost libraries for communicating with the DD Boost server that runs on the Data Domain system. l The DD Boost server that runs on the Data Domain systems. RMAN sets policies that control when backups and replications occur. Administrators manage backup, replication, and restore from a single console and can use all the features of DD Boost, including WAN-efficient replicator software. RMAN manages all the files (collections of data) in the catalog, even those created by the Data Domain system. The Data Domain system exposes pre-made disk volumes called storage units to a DD Boost enabled database server. Multiple database servers, each with the Oracle RMAN agent, can use the same storage unit on a Data Domain system as a storage server. Each database server can run a different operating system, provided that it is supported by Data Domain. The following figure shows an example configuration of the Oracle RMAN agent.
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