Fast-start failover enables the Data Guard broker to rapidly and automatically failover to a previously chosen standby database without requiring manual intervention. This feature increases the availability of your database in the event of a disaster by reducing the need for you to perform a failover operation manually. Fast-start failover can only be used in a broker configuration and can only be configured through DGMGRL or Enterprise Manager.
The observer is an Oracle Call Interface (OCI) client-side component that typically runs on a separate computer and monitors the availability of the primary database. It is integrated into the DGMGRL client-side component. You must use DGMGRL release 12.1 to observe Oracle Databases running release 12.1. There can be only one observer monitoring the broker configuration.
Using Enterprise Manager to Enable Fast-Start Failover
On the Data Guard page, click the Disabled link (next to Fast-Start Failover) to invoke the fast-start failover wizard.
Select the fast-start failover target database and (optional) the observer host. If the observer was not started, click the Configure Observer button.
Specify the observer host and observer Oracle home to indicate where the observer will be started. You can also specify an alternate observer host and alternate observer Oracle home.Enterprise Manager will provide high availability for the observer with this setup. If the original observer or observer node dies, Enterprise Manager will automatically start the observer on the alternate node.
Failover properties and primary database properties related to fast-start failover can also be defined on this page.
The observer data files, named afoXXXXX.dat, are stored in the $ORACLE_HOME/dbs directory. The DGMGRL log file, named dgmgrlXXXXX.log, is stored in the $ORACLE_HOME/rdbms/log directory. XXXXX is a unique number generated by Enterprise Manager and is the same for the observer data file and the DGMGRL log file for a given primary standby database configuration data file and the DGMGRL log file for a given primary standby database configuration. XXXXX changes each time an observer is restarted.
Flashback logging must be enabled on both the primary database and the standby database to enable fast-start failover. If either database does not have flashback logging enabled, the Enable Flashback Logging page is displayed. Specify the fast recovery area location, fast recovery area size, and flashback retention time for each database.
On the Confirmation: Enable Fast-Start Failover page, confirm that you want to enable faststart failover to the named database.
After you confirm that you want to enable fast-start failover to a specific database, the faststart enabling process begins. After the processing steps are complete, you are returned to the Data Guard page.
On the Data Guard Fast-Start Failover Processing page, you can observe the progress of the fast-start failover enabling operation as the following actions are performed:
- Standby redo log files are created on the primary and standby databases.
- The protection mode is upgraded to Maximum Availability (if required).
- The primary database and standby database are restarted (if required).
- Fast-start failover is enabled. start failover is enabled.
- The observer process is started.
Changing the Protection Mode and Disabling Fast and Disabling Fast-Start Failover
If you change the protection mode to a mode that does not support fast-start failover, you implicitly disable fast-start failover.
Using Enterprise Manager to Disable Fast Disable Fast-Start Failover
Click the Enabled link to access the Fast-Start Failover: Change Mode page, where you select the Disable option and the “Stop observer” check box to disable fast-start failover.
Using Enterprise Manager to Suspend Fast Suspend Fast-Start Failover
To suspend fast-start failover, select Disable on the Fast-Start Failover: Change Mode page. Do not select the “Stop observer” check box.
Moving the Observer to a New Host
If the observer host machine fails, you may need to move the observer to a new host. To stop the original observer and start the observer on a new host:
1. Execute the STOP OBSERVER command to sever the link between the original observer and the broker configuration:
DGMGRL> STOP OBSERVER;
2. Execute the SHOW CONFIGURATION VERBOSE and SHOW DATABASE commands to verify that the observer is stopped and the configuration is no longer being observed.
3. Invoke DGMGRL, connect to a database in your configuration, and start the observer on your new host.