23.2. Cross-Datacenter Replication Operations
JBoss Data Grid's Cross-Datacenter Replication operation is explained through the use of an example, as follows:
Figure 23.1. Cross-Datacenter Replication Example
Three sites are configured in this example:
LON, NYC and SFO. Each site hosts a running JBoss Data Grid cluster made up of three to four physical nodes.
The
Users cache is active in all three sites. Changes to the Users cache at the LON site is replicated at the other two sites. The Orders cache, however, is only available locally at the LON site because it is not replicated to the other sites.
The
Users cache can use different replication mechanisms each site. For example, it can back up data synchronously to SFO and asynchronously to NYC and LON.
The
Users cache can also have a different configuration from one site to another. For example, it can be configured as a distributed cache with numOwners set to 2 in the LON site, as a replicated cache in the NYC site and as a distributed cache with numOwners set to 1 in the SFO site.
JGroups is used for communication within each site as well as inter-site communication. Specifically, a JGroups protocol called
RELAY2 facilitates communication between sites. For more information about RELAY2, refer to Section B.7, “About RELAY2”
