Data Guard maximum protection mode Oracle Database Tips by Donald BurlesonDecember 9, 2015

Oracle Data Guard - Protection Modes

The 'no-data-loss' level has two protection modes called MAXIMUM PROTECTION and MAXIMUM AVAILABILITY. MAXIMUM AVAILABILITY is not strictly a 'no-data-loss' protection level and can be categorized in either of the two classes.

maximum protection Mode

The MAXIMUM PROTECTION mode, as the name suggests, guarantees a 'no-data-loss' configuration in any scenario. MAXIMUM PROTECTION mode can be only established using a physical standby database. A logical Oracle instance cannot be used for maximum protection. A transaction on the primary database is not considered complete until it has been posted to at least one of the standby databases that satisfy all the attribute requirements for this mode.

The primary database halts if the transaction cannot complete on at least one Oracle instance that is participating in providing this protection level.

The following attribute of the log_archive_dest_n parameter is required in order to include a physical Oracle instance in maximum protection configuration:

LOG_ARCHIVE_DEST_3='SERVICE=appsstdby1 LGWR SYNC=PARALLEL AFFIRM';

In the above example, the assumption is that the appsstdby1 service is pointing to a physical standby database. The PARALLEL attribute of SYNC is not required but will be useful if more than one physical Oracle instance is included in maximum protection configuration.

Oracle Data Guard - MAXIMUM PROTECTION

In addition to the setting on the primary database, standby redo logs need to be created on all standby sites participating in maximum protection configuration. The following statement can be used to switch a primary database into MAXIMUM PROTECTION mode. The primary database should be mounted but not open to execute this statement:

ALTER DATABASE SET Oracle instance TO MAXIMIZE PROTECTION;

            WARNING - Performance and availability of the primary database is at risk in MAXIMUM PROTECTION mode if adequate network bandwidth and computing resources cannot be provided for the standby database.