13.3.5 Verifying Transparent Application Failover

You can query the FAILOVER_TYPE, FAILOVER_METHOD, and FAILED_OVER columns in the V$SESSION view to verify that TAF is correctly configured.

To view the columns, use a query similar to the following:

SELECT MACHINE, FAILOVER_TYPE, FAILOVER_METHOD, FAILED_OVER, COUNT(*)
FROM V$SESSION
GROUP BY MACHINE, FAILOVER_TYPE, FAILOVER_METHOD, FAILED_OVER;

The output before failover looks similar to the following:

MACHINE              FAILOVER_TYPE FAILOVER_METHOD FAILED_OVER   COUNT(*)
-------------------- ------------- ----------      ---           ----------
sales1               NONE          NONE            NO            11
sales2               SELECT        PRECONNECT      NO             1

The output after failover looks similar to the following:

MACHINE              FAILOVER_TYPE FAILOVER_METHOD FAILED_OVER   COUNT(*)
-------------------- ------------- ----------      ---           ----------
sales2               NONE          NONE            NO            10
sales2               SELECT        PRECONNECT      YES            1

Note:

You can monitor each step of TAF using an appropriately configured OCI TAF CALLBACK function.