Intelligent Management: static clusters versus dynamic clusters
Static clusters in a WAS Network Deployment configuration are different from the dynamic clusters that we can define in Intelligent Management. Both types of clusters support workload balancing, however, dynamic clusters are controlled by autonomic managers that can optimize the performance of the cluster.
- Static cluster
- A static cluster is a group of application servers in a WAS Network Deployment environment that participates in workload management.
- Dynamic cluster
- A dynamic cluster is a fundamental building block of the dynamic operations environment. We must configure dynamic clusters to get Intelligent Management functionality, such as high availability and service policies. Dynamic cluster members can be started and stopped by the application placement controller when running in supervised or automatic mode. Therefore, dynamic clusters are more scalable than static clusters.
Characteristic Static clusters Dynamic clusters Membership We must manually add application servers to static clusters.
We can automatically define cluster members with rules or we can manually define the cluster members. For servers that have complete life cycle management, we can create a membership policy that automatically selects nodes on which to host dynamic cluster members based on different node properties. For servers that have assisted life cycle management, we can statically define the servers that are cluster members.
Cluster management You define the application servers that are in the static cluster and then start or stop all the application servers in the cluster. A dynamic cluster can start and stop instances of servers as required. If the dynamic cluster is in automatic mode, then the server instances stop and start automatically. If the dynamic cluster is in supervised mode, runtime tasks generate to advise the administrator to start and stop servers at certain times. In manual mode, the administrator decides when instances of servers are stopped and started. Cluster templates When you define a static cluster, we can select an application server template on which to base all the application server instances that you create. However, any changes that you make to the template after creating the instances do not change the instances.
When you define a dynamic cluster, we can define an application server template for the application server instances.
After you define the dynamic cluster, we can use the dynamic cluster server template to edit the cluster member properties. The changes are propagated to all of the application server instances.
Application server weights You explicitly assign a weight value to each application server instance. We can also enable the dynamic workload manager to assign weight values. To enable the dynamic workload manager, click Servers > Clusters > cluster_name > Dynamic WLM. The dynamic workload manager is enabled by default and assigns weights to the application server instances. To disable the dynamic workload manager, click Servers > Clusters > cluster_name > Dynamic WLM. Applicability We can use static clusters in a WAS Network Deployment environment, or an Intelligent Management environment. If we use static clusters in an Intelligent Management environment, then the behavior is identical to static clusters in a WAS Network Deployment environment. We can use dynamic clusters in an Intelligent Management environment only.
Create dynamic clusters
Intelligent Management: dynamic cluster administrative tasks