Event Flow With Multiple Hubs

Figure 1.2 shows event flow for region A in the multiple-hub configuration of Two-Hub Configuration With Primaries in Different VMs.

■	Region events originating in VM1 are stored in the local secondary Hub Site1a and are also distributed to VM2. Then in VM2, the events arriving in the local Region are sent to the VM’s primary Hub Site1a, which then forwards them to remote sites.

■	Region events originating in VM2 are sent directly out of the local primary Hub Site1a. They are also distributed to VM1 for cache update and storage in the secondary Hub Site1a.

■	HubSite1b never sees this region’s outgoing events.

Outgoing Region Event Flow for Two-Hub Configuration

 

If you have multiple hubs, make sure you explicitly assign one hub to each distributed region using the hub-id region attribute. If you do not specify a hub for a region, its events will go to all hubs and each hub’s primary will send the message to the remote sites, resulting in duplicate sends.