We have seen overview and prerequisites of fast-start failover in the previous post.

Fast Start Failover in Data Guard

Steps to configure fast start fail over .

Step 1 : Connect to dgmgrl and check the configuration

Step 2 : set faststartfailovertarget property.

Step 3 : set protection mode if not already set using below syntax.

Step 4: a set threshold value for fast-start failover

Default value is 30 seconds.

Step 5 : Setting the LAG limit parameter.

As in my configuration Protection mode is Maximum Performance. I need to set FastStartFailoverLagLimit. Oracle data guard use this property as an acceptable lag-time limit in seconds. If standby database’s applied redo time exceeds this limit fast start failover is allowed.

Default value is 30 seconds , minimum value is 10 seconds.

Note : This parameter is ignored in Maximum Availibility mode.

The maximum performance failover target must be within the specified lag limit of the primary database for the failover to be allowed. If the failover target is more than the specified lag limit behind the primary database, an error is returned.

Step 6: Set property FastStartFailoverPmyShutdown .

Default value is true. If you do not want to shut down Primary database database after fast start failover is triggered  as result of primary redo generation is stalled or primary database loosing connectivity with target standby and observer for more than the time specified by faststartfailoverthreshold  then we need to set it to false.

A value of TRUE causes the primary database to shut down with the ABORT option after the elapse of the number of seconds specified in the FASTSTARTFAILOVERTHRESHOLD property.

Step 7: Automatic reinstatement of database

Step 8: Start observer

Step 9: Enable fast_start failover.

Alert log when we enable Fast_Start Failover :

Viewing Fast_start Failover.

We can check fast_start failover configuration from the v$database view.

We can see here fast_start failover status is synchronized. We can check status, current standby target, threshold value, an observer is present or not and from which host observer is running.

Stay tuned for More articles on Oracle DataGuard

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