High availability catalog service

A catalog service domain is the data grid of catalog servers you are using, which retain topology information for all of the container servers in your eXtreme Scale environment. The catalog service controls balancing and routing for all clients.

For more information about catalog servers, see Catalog service.

Figure 1. Catalog service domain
A catalog service domain consists of multiple Java virtual machines, including a master JVM and a number of backup JVMs.

When multiple catalog servers start, one of the servers is elected as the master catalog server that accepts heartbeats and handles system data changes in response to any catalog service or container changes.

When clients contact any one of the catalog servers, the routing table for the catalog service domain is propagated to the clients through the Common Object Request Broker Architecture (CORBA) service context.

Configure at least three catalog servers in the catalog service domain. Catalog servers must be installed on separate nodes or separate installation images from your container servers to ensure that you can seamlessly upgrade your servers at a later date. If your configuration has zones, you can configure one catalog server per zone.

When a container server contacts one of the catalog servers, the routing table for the catalog service domain is also propagated to the catalog server and container server through the CORBA service context. Furthermore, if the contacted catalog server is not currently the master catalog server, the request is automatically rerouted to the current master catalog server and the routing table for the catalog server is updated.

Note: A catalog service domain and the container server data grid are very different. The catalog service domain is for high availability of your system data. The container server data grid is for your data high availability, scalability, and workload management. Therefore, two different routing tables exist: the routing table for the catalog service domain and the routing table for the container server data grid shards.