If the active sequencer or the Unity server on which it resides fails, the standby sequencer automatically assumes the role of the active sequencer after a specified timeout period (with a default of 5 minutes). This happens if the standby sequencer can connect to the database running on all managed Teradata systems in both data centers. If the standby sequencer cannot connect to all Teradata systems, it does not attempt to take over, in case there is only a network issue and not an actual failure of the Unity server.
Use the Component view in the Unity UI to determine which component or Unity server is down.
A SEQUENCER STATUS command issued on the standby sequencer displays the time remaining before the standby sequencer automatically assumes the active role. It also displays the checks performed by the standby to confirm the other Unity server is down.
unityadmin> sequencer status; HA Status : Down/Unknown Log Replication Mode : Asynchronous Failover Mode : Automatic Automatic Failover Status ------------------------- Sequencer : region2_seq Time Remaining Before Failover : 290 seconds Failover Conditions : Check standby sequencer can connect to all managed systems (done) Check active sequencer has no heartbeat on all managed systems (running) Check active sequencer has no transaction on all managed systems (running) Individual Sequencer States --------------------------- unity2:5344 : STANDBY (SYNCHRONIZED) unknown host/port : DOWN …