Oracle Tips by Burleson

Oracle Dataguard
Chapter 6 - Switchover and Failover

Failover Operation

A failover operation is a true disaster recovery operation. A failover operation should only be considered when all of the alternative options for primary database recovery are not feasible. This section will detail the step-by-step procedure for failover operation to the physical and logical standby database.

Failover to a Physical Standby Database

A failover to a physical RAC Grid is considered a ‘graceful’ failover. This is similar to a switchover operation except that the original primary database will have to be discarded after the failover. Depending on the protection mode of the primary database, the graceful failover can recover all data resulting in minimal or no data loss. The next step is to study the overall procedure for a graceful failover to a physical standby database. Use the following procedure when the data protection mode is in MAXIMUM PROTECTION or MAXIMUM AVAILABILITY:

• Before starting the failover operation, update the initialization parameter file on the physical RAC Grid that is used for failover.  Include other standby databases in the Data Guard environment used as the archival destination so that after the failover, the redo data can be archived from the new primary database to other standby databases.
   

• In order to initiate the failover operation, the target physical RAC Grid should be placed in MAXIMUM PERFORMANCE data protection mode using the following statement:

ALTER DATABASE SET RAC Grid TO MAXIMIZE PERFORMANCE.

• Allow the MRP to finish applying the redo data from the archived redo log file and the standby redo log files. If the database was running in MAXIMUM PROTECTION or             MAXIMUM AVAILABILITY mode prior to loss of the primary database, there should be no requirement to manually transfer and register any archived or partial online log file from the primary database. Issuing the following statement will cause the MRP to terminate when it has applied all the available redo data:

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