RMAN Fundamentals
You need to be familiar with a few RMAN concepts as you read the following sections:
- Server processes
RMAN uses a number of server processes to operate. These server processes are started whenever you start RMAN or use one of its features—for example, when you connect to a catalog or allocate a channel for backup.
- Channel
A channel is an RMAN server process that communicates with a particular backup device. You must allocate a channel before you can begin any backup operations.
- Target and catalog
RMAN can interact with two different Oracle databases. The target database is the database for which you are performing backup or recovery operations. The catalog is a database that acts as a repository for information about RMAN activities. The catalog is normally another Oracle database on a different Oracle host; using a different host prevents a failure from destroying the very catalog information that will be needed to recover from that failure.
The catalog includes a specific schema that will hold the relevant information. To create a catalog for RMAN, you first connect to the catalog database with RMAN and issue the CREATE CATALOG command. If you want to use a catalog for RMAN, you will have to register any target databases using RMAN’s REGISTER command before those databases will be able to use the catalog.
You don’t have to use a catalog, because RMAN includes information about any backup in the target database’s control files. However, the catalog gives you more ...