Negotiations

On startup, or whenever an active instance shuts down, the cluster instances negotiate to determine which one will be active.

Priority is given to the instance with the highest ID (as specified in the instance_id property in the cluster configuration object). If not all instances are running during the negotiation process, however, then another instance may be designated active instead.

If instance_ids are not explicitly set, then instances are assigned random IDs each time they are started. If instances are regularly re-started, this introduces some randomness with regard to which instance is given priority during negotiation.

After negotiation, all the non-active instances will enter the inactive state, in which they do not process any Content Store updates. If the active instance shuts down or disappears, the idle instances will re-enter negotiations to find a new active instance.