Clustering

8

Introducing Clustering

Cluster Constraints

Preparation

Clustering Configuration

Step-By-Step Application Server Clustering

Clustered Application Servers Communication

Clustering Summary

Starting Clusters Durably

Introducing Clustering

Clustering transparently balances the computing load for this application’s EJB components--rule engine, scheduler, logger, Business Object Manager (BOM), workspaces and mediation. This is especially beneficial for the applications’ communication with the database storing its business data.

By default, this application supports the distribution of its processes. It distributes the load per client (not per request). Except for Mediation clustering, fail-over or high availability clustering is an optional add-on. To make a genuine highly available system, you must cluster application servers, mediation servers, and database servers (Oracle). Consult your sales representative for the licensing requirements for fail-over, or high availability clustering.

The following are some of the benefits of clustering:

• Elimination of bottlenecks and single-point failures --Clustering several servers distributes computing tasks, and enhances performance. You can even dynamically add a server to the cluster to meet increasing user demand. Replication protects your application and users’ state to ensure that the failures--like server crashes--can be fully masked from the user and application.

• Transparency to your applications and application developers--developers do not have to deal with intricacies of replication and load balancing. This means developers do not have to modify their application components to run in a clustered environment.

• Hardware and OS independence--You can use clustering across disparate hardware and operating system platforms.

The requirements outlined in the following sections apply to both Solaris and Windows installations.

Figure 8-1  Typical Clustering

Clustering typically distributes computing power for the following application components:

• Application Server -- This manages rules, events and (BOM) database communication.

• Database Servers -- You can cluster the Oracle database servers. See Installing Oracle. References to database servers below apply to all supported databases.

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You cannot cluster the embedded database.

• Rather than clustering, you can make mediation servers highly available. See Mediation Clustering.

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If Mediation Servers or clients are outside a firewall from the Application Server, you must disable multicast connections to Application Servers. See Disabling Multicast.