Balancing workloads with clusters

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

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.

Overview

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. Configure a backup cluster.

   A backup cluster handles requests if the primary cluster fails.

7. 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.

8. 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.

   • Tune the behavior of the workload management run time.

     The default timeout value for the com.ibm.CORBA.RequestTimeout JVM property is 0, which means wait forever. Because this is not a good setting to have for failover situations, if your application is experiencing problems with timeouts or 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 com.ibm.websphere.wlm.unusable.interval property.

What to do next

-Dcom.ibm.CORBA.BootstrapHost=machine_name

Related concepts