In case you are using a IBM WebSphere clustered environment that consists of a static number of members, you may find yourself in the situation where the overall workload of your site reaches the top configured levels of each member's resources (for example: number of maximum client sessions per server or allocated memory). In this case, you might find useful to switch to a dynamic cluster.
Dynamic cluster can be achieved by installing IBM WebSphere Virtual Enterprise that can monitor performance and load information and dynamically creates and removes cluster members based on the workload for the configured dynamic cluster. WebSphere Virtual Enterprise provides an advanced, intelligent routing function called the On Demand Router that has all of the features of the HTTP Server plug-in with the additional ability to define routing and service policies. The On Demand Router is required if you are setting up a dynamic clustered environment.
When using a dynamic cluster you have the following options:
- set the minimum number of cluster instances: This indicates the minimum number of cluster members that should be running at any given time in this cluster. You have the option to stop the instances of the dynamic cluster in case other dynamic cluster needs resources.
- set the maximum number of cluster instances: This indicates the maximum number of cluster members that should be running at any given time in this cluster. You have the alternative to set manually the maximum number or to switch to a no limit of instances option.
- set the vertical stacking of instances on a node: This allows the dynamic cluster to start more than one vertical cluster member on the node. A vertical cluster member is any additional cluster member that exists on the same node as your main cluster member. Using this option will automatically generate vertical cluster members.
- set the isolation preference: Set this option if you have more than one dynamic cluster running on a single node and want to restrict the number of clusters running on a node at any given time.
All the vertical cluster members have to be configured separately.
There is a difference in the installation and configuration steps that need to be done in order to achieve a static and a dynamic cluster. For dynamic clusters, WebSphere Virtual Enterprise has to be installed on all Portal nodes and on the deployment manager node. The tasks that you run to configure a dynamic cluster member are different from the tasks used to create static members. So make sure you are following the right configuration path and you run the appropriate tasks.
For details about configuring a WebSphere Portal dynamic cluster on IBM AIX operating system, visit: