How to Enable fast Start Failover in Maximum Performance Mode
FSFO can be enabled even if the configuration is operating in Maximum Performance mode by setting configuration Property FastStartFailoverLagLimit
Configuration property FastStartFailoverLagLimit allows to occur failover to Physical standby database even if it is lagging behind Primary database. The value is defined in seconds.
If the physical standby database is lagging behind Primary with in this limit and Primary is not available, Failover can occur. In this situation it is acceptable by business to have data loss.
If the physical standby database is lagging behind Primary with in this limit and Primary is not available, Failover can occur. In this situation it is acceptable by business to have data loss.
The value for FastStartFailoverLagLimit must not be less than RPO (recovery point objective) defined by business.The Property is used only if the configuration is operating in MaxPerformance mode and FSFO is enabled. B
Broker Default value is 30 seconds
Minimum configurable value is 5 sec
Value 0 means property is ignored and is the default value in case of MaxAvailability and MaxProtection mode
DGMGRL> edit configuration set property FastStartFailoverLagLimit=180;
Property "FastStartFailoverLagLimit" updated.
Property "FastStartFailoverLagLimit" updated.
In the example above I set FastStartFailoverLagLimit to 3 min. This means if my Physical standby database is lagging behind Primary for less than 3 min (say 2 min) and Primary become unavailable, Failover will proceed.
However if my Physical standby database is lagging behind Primary for more than 3 min (Say 5 min) Failover will not be allowed to ensure to prevent any unwanted data loss.
If configuration is not operating in Maximum Performance Mode , attempting to modify the property will result in following error
DGMGRL> edit configuration set property FastStartFailoverLagLimit=180;
Error: ORA-16903: change of FastStartFailoverLagLimit property violates configuration protection mode
Error: ORA-16903: change of FastStartFailoverLagLimit property violates configuration protection mode
Failed.
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