IBM WebSphere Application Server clustering

Clustering

In general, clustering is configured in customer environments to provide failover protection and scalability for Application Servers. This section will provide general steps for configuring clustering on WebSphere Application Server environments. More details can be found in the WebSphere 6.1 infocenter:
http://publib.boulder.ibm.com/infocenter/wasinfo/v6r1/index.jsp?topic=/com.ibm.websphere.nd.doc/info/ae/ae/trun_wlm_cluster_v61.html

Vertical Clustering

Clustering with vertical cluster members refers to the practice of defining cluster members of an application server on the same physical machine. Experience has shown that a single application server, which is implemented by a single JVM process, cannot always fully utilize the processor power and RAM of a large multiprocessor machine. Clustering with vertical cluster members provides a straightforward mechanism to create multiple JVM processes that together can fully use all the processing power and memory available.
Important: Before clustering a WebSphere instance, it strongly recommended that you backup the WebSphere Application Server administrative configuration. Backing up the administrative configuration will allow you to restore the original configuration if clustering fails during the clustering process.

To create a cluster with vertical cluster members:
1. Complete the installation of a WebSphere node using the standard product install information.
2. Create a WebSphere Cluster using the WebSphere Guided Activity Wizard for clustering.
3. Add additional cluster members.
4. Configure failover
5. Set relative weighting for cluster members.
6. Start the new WebSphere cluster.

Horizontal Clustering

Clustering with horizontal cluster members refers to the traditional practice of defining cluster members of an application server on multiple physical machines, allowing a single application to span several machines while presenting a single system image. Clustering with horizontal cluster members can provide increased throughput and high availability.
Important: Before clustering a WebSphere Commerce instance, it strongly recommended that you backup the WebSphere Application Server administrative configuration. Backing up the administrative configuration will allow you to restore the original configuration if clustering fails during the clustering process.

To create a cluster with horizontal cluster members:
1. Complete the installation of a WebSphere Network Deployment node using the standard product install information.
2. Prepare additional WebSphere nodes for each node to be added to the cluster.
3. Define the JDBC provider path for each node that contains a server that is or will be a member of the WebSphere cluster.
4. Create a WebSphere Cluster (WebSphere provides a wizard under Guided Activities).
5. Add the additional cluster members.
6. Configure failover
7. Set relative weighting for cluster members.
8. Start the new WebSphere cluster.