Dispatcher Failover - Teradata Unity

Teradata® Unity™ User Guide

Product
Teradata Unity
Release Number
16.20
Published
May 2019
Language
English (United States)
Last Update
2019-05-23
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dzf1517499323110.ditamap
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dita:id
B035-2520
lifecycle
previous
Product Category
Analytical Ecosystem

Dispatcher failover occurs when the sequencer loses connection to one of its dispatchers. The sequencer relies on the heartbeat table to know if the dispatcher is still connected to the managed system or not.

Each active dispatcher logs timestamps on the heartbeat table every HeartbeatTableUpdateFrequency seconds (by default 30 seconds).

If the difference between current time and the last timestamp exceeds HeartbeatTableDispatcherFailoverDelay, (by default 120 seconds, or four times the value of HeartbeatTableUpdateFrequency), the sequencer may proceed with dispatcher failover.

Both HeartbeatTableUpdateFrequency and HeartbeatTableDispatcherFailoverDelay are configurable via unityadmin.

Variable Definition
HeartbeatTableUpdateFrequency Frequency with which the dispatcher updates the heartbeat table. The variable is global (used by both dispatcher and sequencer processes), has a minimum valid value of 30, defined in seconds.
HeartbeatTableDispatcherFailoverDelay Delay after which a failover can occur. The variable is global (used by both dispatcher and sequencer processes) and has a minimum valid value of four times the frequency (120 seconds if frequency is 30 seconds, user may set it to a higher value).