Balancing workloads

You should use server clusters and cluster members to monitor and manage the workloads of application servers.

Before you begin

You should understand your options for configuring application servers. To assist you in understanding how to configure and use clusters for workload management, consider this scenario. Client requests are distributed among the cluster members on a single machine. A client refers to any servlet, Java™ application, or other program or component that connects the end user and the application server that is being accessed.

[z/OS]In more complex workload management scenarios, you can distribute cluster members within the same sysplex.

About this task

Perform the following steps if you decide to use clusters to balance your workload.

Procedure

  1. Decide which application server you want to cluster.
  2. Decide whether you want to replicate data. Replication is a service that transfers data, objects, or events among application servers.

    You can create a replication domain when creating a cluster.

  3. Deploy the application onto the application server.
  4. Create a cluster.

    After configuring the application server and the application components exactly as you want them to be, create a cluster. The original server instance becomes a cluster member that is administered through the cluster.

  5. Create one or more cluster members.
  6. Start the cluster.

    When you start the cluster, all of the application servers that are members of that cluster start. Workload management automatically begins after the cluster members start.

  7. After the cluster is running, you can perform the following tasks:
    • Stop the cluster.
    • Upgrade the applications that are installed on the cluster members.
    • Detect and handle problems with server clusters and their workloads.
    • Change how frequently the workload management state of the client refreshes.

      The default timeout value for the com.ibm.CORBA.RequestTimeout JVM property is 0, which means wait forever. This default value is not a good setting to have for failover situations. Therefore, if your application is experiencing problems with timeouts, or if you have configured your system for failover situations, use the -CCD option on the LaunchClient command to set an appropriate non-zero value for this property.

      If the workload management state of the client refreshes too soon or too late, change the interval setting of the JVM custom property com.ibm.websphere.wlm.unusable.interval.