Data Guard Switchover and Failover: A DBA Playbook
Switchover and failover are the two role-transition operations in Oracle Data Guard. Switchover is a planned, graceful transition (both databases remain available throughout). Failover is an emergency response to primary failure. Having a tested, documented playbook for both is a MAA operational requirement — discovering the procedure on the night of a failure is not a plan. Terminology Recap Term Trigger Data Loss? Primary State Afterward Switchover Planned maintenance None Becomes standby (online) Failover Primary failure Possible (ASYNC) or None (SYNC) Unavailable (failed) Reinstate After failover N/A Failed primary becomes new standby Always use the Data Guard Broker (DGMGRL) for role transitions. Direct SQL*Plus procedures are error-prone and lack the consistency checks the Broker provides. ...