The two most popular type of clusters in WebSphere are static clusters and dynamic clusters. A dynamic cluster contains features that are not available in a static cluster, which makes a dynamic cluster appealing. For example, following are some capabilities of a dynamic cluster:
- A dynamic cluster can be configured to automatically start the application servers in the dynamic a cluster when demand is high, and stop some of the application servers in the cluster when demand is low.
- A dynamic cluster uses Dynamic workload management (DWLM) to distribute work across the cluster members, to prevent one of the cluster members from being overwhelmed with requests.
Convert a static cluster into a dynamic cluster
This assumes you have already created a static cluster.
- In the left panel of the WebSphere web console, expand Servers > Clusters, and select Dynamic clusters.
- Select New.
- At Step 1, select WebSphere application server and select Next.
- At Step 2, select Automatically define new cluster members with rule or Manually define cluster members and select Next.
- At Step 3, if you selected Manually define cluster members, select an existing static cluster and select Next.
- At Step 5, select your preferred properties, and select Next.
- Select Finish.
- Select Save.
The cluster will no longer be listed at Servers > Clusters > WebSphere application server clusters, and will instead be listed at Servers > Clusters > Dynamic clusters.
At Servers > Server types > WebSphere application servers, the servers in the cluster will be listed. In this example, server01 is not part of a cluster, and server03 and server04 are members of cluster1. This view also can be used to know if the JVMs are in a vertical or horizontal cluster. In this example, server03 and server04 are in a horizontal cluster, as the servers are on different servers (was1 / was2).
Servers > Clusters > Dynamic clusters > cluster_name > Dynamic cluster members will display the cluster members.