The members of an Oracle Data Guard configuration are connected by Oracle Net and may be dispersed geographically.There are no restrictions on where the members of an Oracle Data Guard configuration are located as long as they can communicate with each other.For example, you can have a standby database in the same data center as the primary database, along with two standbys in another data center.

Oracle Data Guard ensures high availability, data protection, and disaster recovery for enterprise data.

Oracle Data Guard provides a comprehensive set of services that create, maintain, manage, and monitor one or more standby databases to enable production Oracle databases to survive disasters and data corruptions.

Oracle Data Guard maintains these standby databases as copies of the production database.

Then, if the production database becomes unavailable because of a planned or an unplanned outage, Oracle Data Guard can switch any standby database to the production role, minimizing the downtime associated with the outage.

Oracle Data Guard can be used with traditional backup, restoration, and cluster techniques to provide a high level of data protection and data availability.

Oracle Data Guard transport services are also used by other Oracle features such as Oracle Streams and Oracle Golden Gate for efficient and reliable transmission of redo from a source database to one or more remote destinations.With Oracle Data Guard, administrators can optionally improve production database performance by offloading resource-intensive backup and reporting operations to standby systems.This chapter includes the following topics that describe the highlights of Oracle Data Guard: can contain one primary database and up to thirty destinations.The broker provides a command-line interface (DGMGRL) and a graphical user interface that is integrated in Oracle Enterprise Manager Cloud Control.An Oracle Data Guard configuration contains one production database, also referred to as the primary database, that functions in the primary role.This is the database that is accessed by most of your applications.