Data Guard Broker
Data guard broker is an assistance utility given along with the Oralce Software, which can be used to create and manage the data guard configurations. Data guard broker consists of server side and client side components.
The server side components include dataguard monitor (DMON) and configuration files. The client side components include Data guard manager and Command line interface (CLI).
Data guard broker manages a data guard configuration using a broker management model. The broker management model is a hierarchial structure comprised of configuration,site and database resources. Broker can manage all three layers of the management model.
Dataguard broker can manage the proimary database and upto nine (9) standby databases in one configuration (in Oacle 10g). These nine standby database can be a mixture of physical and logical standby databases. Standby databases can be created using data guard broker. In addition, it can be used to add an existing standby database to a configuration.
When a standby database is created using Data guard broker, broker takes care of the entire set of supportinf files such as SPFILE, oracle net configuration files, etc., if in case an existing standby database is to be added to the data guard configuration, the SPFILE and oracle net files must be explicitly configured manually before the standby database is added to a configuration. If data guard broker is to be used for the management of standby databases, SPFILE must be used on all the databases.
Some of the advantages of using dataguard broker are listed:
1. It is a centralized management tool that can be used to manage the data guard configuration using a CLI / GUI interface.
2. It reduces the complexity of role management services (Switchover and Failover).
3. It provides an extensive health check mechanism for both the primary and standby databases.
4. It can be used to gather useful statistics for fine tuning the log transfer and log appky services.
In oracle 9i Dataguard broker cannot be used with Oracle Real Application Cluster (RAC). RAC support is provided with Oracle 10g.