Creating a cluster in IBM WAS ND is one of the essential tasks for WebSphere administrator and necessary to provide application high-availability & workload balancing. There are a lot of benefits in having an application deployed in cluster mode, like:
Ensure application is always available from one of the cluster members High-availability if one or more JVM is down No issue if one of the cluster JVM’s physical server is down No or minimum downtime during restart Easy maintenance No need to deploy on multiple JVM instead just select the cluster as target
There are two types of clustering available to scale your WebSphere applications. Horizontal Cluster – One of the widely used clustering type where you host your applications on multiple JVM servers (physical or VM) using a single cluster.
Vertical Cluster – having all JVM servers under cluster on single physical or VM server. A vertical cluster can be SPOF (Single point of failure) when a server goes down.
Note: With WebSphere 8.5 or higher you can also create a dynamic cluster which is different from a traditional cluster. So based on the requirement you got to decide which clustering type to use. WebSphere cluster creation is possible either through GUI (WAS Administrative Console) or command line (wsadmin/script). The following is through the admin console. The following is tested in WebSphere ND 9.
Creating WebSphere Cluster using GUI
Login to WAD DMGR Admin Console Navigate Servers » Clusters » WebSphere application server clusters
Click New » Enter the “Cluster name” and click Next
Enter the Cluster member name and select the node where you want to create
You have the option to create the member using an application server template, using an existing JVM as a template, convert existing JVM as a cluster member or create an empty cluster.
I’ve chosen to create using a default template, click Next You can create additional cluster member on next screen if you need, click Next
Review the summary and click Finish
Review and synchronize the configuration changes
This concludes cluster is created and ready to be used. Let’s verify.
Go to WebSphere application servers under “Server Types.”
As you can see, I’ve created tow JVM under “Cluster-1”. By default, they will be stopped state.
To start, you can either start the JVM or whole cluster
If you have multiple JVM’s in a cluster and need to restart all, then you can restart the whole cluster. Tip: if you need to create JVM in existing cluster then you can do as following.
Go to Servers » Clusters » WebSphere application server clusters Click the Cluster from the list where you want to create a JVM Click “Cluster members” under Additional Properties
Click New Enter the JVM name » select the node where you want to get it created and click “Add Member.”
Once added, click Next and then Finish
Don’t forget to review and synchronize the changes. I hope this quick guide helps you understand how to create a cluster in IBM WebSphere Application Server.
