Multiple Masters Configuration Overview

You can also configure the Sun Cluster HA for Sun Java System Application Server to be mastered on multiple nodes at the same time. The multiple masters configuration provides scalability by using a front-end web tier to direct requests to the application servers. The pass-through plugin that the application server provides must be used with a front-end web tier to direct requests to one of the running Sun Java System Application Server instances.

A highly available Sun Java System Web Server is configured to run on the cluster listening on a logical hostname. If the web tier is running on the same cluster as the application server, the plugin should be configured to pass requests to the cluster private IP addresses. The Sun Java System Web Server instance can also be configured to run on a different cluster. If the web tier is running on a separate cluster, the plugin is configured to pass requests to the physical hostnames of the cluster members that can run the Sun Java System Application Server resource. An example of a physical hostname is phys-schost-1.

The Sun Cluster HA for Sun Java System Application Server configurations that are mastered on multiple nodes can use the private interconnect to direct traffic between the Sun Java System Web Server to the Sun Java System Application Server.

If you configure the Sun Cluster HA for Sun Java System Application Server as a service that is mastered on multiple nodes at the same time, you must install and configure the Sun Java System Web Server. The Sun Java System Web Server configuration must be the same on all cluster nodes.

Multiple instances of the Sun Java System Application Server can be load balanced. To enable load-balancing, install the Sun Java System Application Server plugin into the Sun Java System Web Server configuration. The Sun Java System Web Server can be configured as a failover or scalable resource when it is used as a front-end to the Sun Java System Application Server.

The Sun Java System Application Server instance is configured so that its HTTP Listeners listen on all interfaces (0.0.0.0), which is the default for Sun Java System Application Servers.

For a data service mastered on multiple nodes, the IIOP listeners are not highly available.

The following figure illustrates a configuration for a Sun Java System Application Server that masters the resource on two nodes at the same time.

Figure 1–2 Two-Node Cluster With Data Service Mastered on Multiple Nodes