If your deployment requires a Number of hosts significantly larger than 16, you might need to add dedicated consumers to the topology.
The following figure assumes that the Number of hosts is 24 and, for simplicity, shows only a portion of the topology. (The remaining 10 servers would have an identical configuration, with a total of 8 masters and 16 consumers.
A change log can be enabled on any of these consumers if you need to do the following:
Promote the consumer to a master in the event of an outage
Perform a binary initialization from a master to any one of the consumers
If the Number of hosts is several hundred, you might want to add hubs to the topology. In such a case, there should be more hubs than masters, with up to 10 hubs for each master. Each hub should handle replication to only 20 consumers at most.
No topology should have the same number of hubs as masters, or the same number of hubs as consumers.
Configuring a “one-way” master (a master that receives replication changes but does not send them) in a multi-master topology is not recommended and can break replication to that master.