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As a rule, any Master Controller is in charge of running its own tasks. In addition, it takes over Failover tasks for which the owner is not visibly producing heartbeats indicating its health, and where no other healthy Master Controllers with better failover priority (lower value) are available. Each Master Controller has its own list of failover priorities, deciding which Master Controller becomes the next top MC in a Failover situation. For best behaviour, it is recommended to list all Master Controllers that are visible in the list of Failover Priorities. In order to prevent the local Master Controller becoming the top Master Controller for taking over its own "Suspend duty in Failover" Tasks in case of a manual failover, it is common to specify all other Master Controllers first, and put the local Master Controllers' Failover Priority last. If there is a tertiary backup system that needs to take over from MC00 and MC01, then the tertiary system is always specified last.
Example:
| MC | Failover priorities order by rank | Example |
|---|---|---|
| MC00 | MC01 MC00 MC02 | The lowest failover priority integer value indicates the highest rank. For instance, when MC01=1 MC02MC00=2 MC00MC02=99 are defined on MC00 this indicates the failover priority order is "MC01 MC00 MC02 MC00'. In this case the TaskManager on MC00 runs "Suspend duty in Failover" Tasks when
Three Master Controllers in a single synchronization pool with:
Each MC that is not in Failover mode can become top MC for Failover Tasks owned by other MCs as soon as no recent heartbeats (5 minutes threshold) are received from higher ordered remote MCs. |
| MC01 | MC00 MC01 MC02 | |
| MC02 | MC00 MC01 MC02 |
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