Balancing workloads with clusters

Consider your options for configuring application servers. See Managing application servers for more information.

To monitor application servers and manage the workloads of servers, use server clusters and cluster members.

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.) In more complex workload management scenarios, you can distribute cluster members to remote machines.

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. See Replicating data across application servers in a cluster for more information. You can create a replication domain when creating a cluster.

3. Deploy the application onto the application server.

4. 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. See Creating clusters for more information.

5. You can create one or more cluster members of the cluster.

6. Configure a backup cluster that handles requests if the primary cluster fails.

7. Start all of the application servers by starting the cluster. Workload management automatically begins when you start the cluster members of the application server.

8. Once you have the cluster running, you can perform the following tasks:

   • Stop the cluster.

   • Upgrade applications on clusters.

   • Detect and handle problems with server clusters and their workloads.

   • Tune the behavior of the workload management run time. If your application is experiencing problems with timeouts or your network experiences extreme latency, change the timeout interval for the com.ibm.CORBA.RequestTimeout property. Or, if the workload management state of the client is refreshing too soon or too late, change the interval for the com.ibm.websphere.wlm.unusable.interval property.

What to do next

For stand-alone Java clients, define a bootstrap host. Stand-alone Java clients are clients that are located on a different machine from the application server and have no administrative server. Add the following line to the Java Virtual Machine (JVM) arguments for the client:

-Dcom.ibm.CORBA.BootstrapHost=machine_name