Oracle Data Guard enables Oracle databases to survive disasters and data corruptions by providing a comprehensive set of services that create, maintain, manage, and monitor a standby database. Oracle Data Guard maintains the standby database as a copy of the primary database. If the primary database becomes unavailable because of a planned or an unplanned outage, you can switch the standby database to the primary role, minimizing the downtime associated with the outage.
To learn about using Oracle Data Guard and Oracle Real Application Clusters together, see Using Oracle Real Application Clusters (RAC) and Oracle Data Guard Together in Database Cloud Service.
Creating an Oracle Data Guard Configuration
To learn about creating an Oracle Data Guard configuration with a primary database on your own system and a standby database in the cloud, see Creating a Hybrid DR Deployment.
To create an Oracle Data Guard configuration in Database Cloud Service, make the following choices in the Create Instance wizard:
For Software Edition, choose Enterprise Edition, Enterprise Edition - High Performance, or Enterprise Edition - Extreme Performance.
For Database Type, choose Single Instance with Data Guard Standby.
For Standby Database Configuration (on the Instance Details page), choose where you want the standby database placed in relation to the primary database:
High Availability—The standby database is placed in a different availability domain from the primary database, thus providing isolation at the infrastructure level.
Disaster Recovery—The standby database is placed in a different data center from the primary database, thus providing isolation at the infrastructure level and geographical separation to support availability despite catastrophic events.
For further details, see Creating a Customized Database Deployment.
When you make these choices, Database Cloud Service creates an Oracle Data Guard configuration with a primary database and a single standby database, hosting the databases on two independent compute nodes. It creates these compute nodes using computing, storage and networking resources provided by Oracle Cloud Infrastructure Compute Classic or Oracle Cloud Infrastructure.
If you selected Enterprise Edition - Extreme Performance, the configuration includes Oracle Active Data Guard. See "Opening a Physical Standby Database" in Oracle Data Guard Concepts and Administration for Release 18, 12.2, 12.1, or 11.2 for more information on the real-time query and the automatic block media recovery features of Oracle Active Data Guard.
Oracle Database Cloud Service does not currently include the fast-start failover (FSFO) feature of Oracle Data Guard. In Database Cloud Service, you perform failover operations manually, as described in Performing a Manual Failover Operation.
In a Database Cloud Service database deployment, you can use the Oracle Database Cloud Service console or the
dataguard subcommand of the
dbaascli utility to perform many Data Guard operations. For more information, see Administering a Data Guard Configuration.
You can also manage primary and standby databases by using the SQL command-line interface or the Oracle Data Guard broker interfaces. The broker provides a command-line interface (DGMGRL) and a graphical user interface through Oracle Enterprise Manager Cloud Control.
You must use the
database changepassword subcommand of the
dbaascli utility to change the password of the
SYS user in your Oracle Data Guard configuration to ensure that the password file on the standby database node is updated and cloud tooling works correctly. See Changing the SYS Password for details.
More About Oracle Data Guard
Oracle Data Guard provides a comprehensive set of services that create, maintain, manage, and monitor a standby database to enable Oracle databases to survive disasters and data corruptions.
An Oracle Data Guard configuration contains one primary database, which is the database that is accessed by most of your applications. An Oracle Data Guard configuration also contains up to thirty standby destinations, connected by Oracle Net Services. However, the Oracle Data Guard configuration in Database Cloud Service includes one primary database and one standby database.
A standby database is a transactionally consistent copy of the primary database. Once created, Oracle Data Guard automatically maintains each standby database by transmitting redo data from the primary database and then applying the redo to the standby database. In an Oracle Data Guard configuration on Database Cloud Service, the standby database is a physical standby database. A physical standby database provides a physically identical copy of the primary database, with on-disk database structures that are identical to the primary database on a block-for-block basis. A physical standby database is kept synchronized with the primary database, through Redo Apply, which recovers the redo data received from the primary database and applies the redo to the physical standby database.
Enterprise Edition - Extreme Performance includes Oracle Active Data Guard. Oracle Active Data Guard provides read-only access to the physical standby database while it is synchronized with the primary database, enabling minimal latency between reporting and transactional data. With the Oracle Active Data Guard feature known as real-time query, Redo Apply can be active while the physical standby database is open, thus allowing queries to return results that are identical to what would be returned from the primary database. See "Opening a Physical Standby Database" in Oracle Data Guard Concepts and Administration for Release 18, 12.2, 12.1 or 11.2 for additional information about real-time query.