Clustered servers topology
To increase capacity and availability, multiple portal servers can be clustered using IBM® WebSphere® Application Server Network Deployment, where the portals share a common configuration and load is distributed evenly across all cluster instances.
IBM WebSphere Portal comes standard with WebSphere Application Server Network Deployment, a distribution of IBM WebSphere Application Server that provides a Deployment Manager server type for centrally managing and clustering a series of servers. To cluster a series of portal servers means that all portal instances share the same configuration, including database, applications, and portlets, and site design. The cluster provides a domain against which most administrative actions are performed once and synchronized with each server in the cluster. This both simplifies administration as well as ensures that all cluster members are configured and behave identically.
A server cluster also provides a shared domain in which session and cache data can be replicated and kept consistent across all members of the cluster. The cluster also provides an application synchronization mechanism that ensures consistent application management (start, stop, updates, etc.) across the cluster.
WebSphere Application Server provides an HTTP Server plug-in that can balance user traffic across all members of the cluster, and through a feature called “session affinity”, ensure that a user remains bound to a specific cluster instance for the duration of their session, to improve efficiency and performance. Additionally, in the event a cluster member is down, the workload management features of the plug-in will recognize that the instance is no longer available and will route traffic around it.
You can install IBM WebSphere Virtual Enterprise to create a dynamic cluster that monitors performance and load information and is able to dynamically create and remove cluster members based on the workload. 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.
There are two types of clusters: vertical and horizontal clusters. Most large-scale deployments are mixtures of both cluster types.
It is also possible to deploy multiple portal clusters to improve availability, failover, and disaster recovery.
Before installing WebSphere Portal and creating your cluster, you should review all the topics under Cluster considerations to help you plan a successful cluster deployment.