A failover is when the primary database (all instances of a RAC primary database) fails and one of the standby databases is transitioned to take over the primary role. Failover is performed only in the event of a catastrophic failure of the primary database, and there is no possibility of recovering the primary database in a timely manner. Failover may or may not result in data loss depending on the protection mode in effect at the time of the failover.
The switchback does not exists as it is a switchover but in the reserve order, which would restore the database back on its original server.
In this video we will test DG switchover, reverse switchover (switchback) and failover using DG broker.
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