Network Deployment (Distributed operating systems), v8.0 > Set up the application serving environment


Balancing workloads

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.

In more complex workload management scenarios, you can distribute cluster members to remote machines. Perform the following steps if you decide to use clusters to balance your workload.


Procedure

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

    We 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.
    • 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 the application is experiencing problems with timeouts, or if we have configured the 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.


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
where machine_name is the name of the machine on which the administrative server is running.


Related


Clusters and workload management
Workload management for all platforms except z/OS
Techniques for managing state
Create clusters
Add members to a cluster
Create backup clusters
Start clusters
Stop clusters
Replicating data across application servers in a cluster
Delete clusters
Delete specific cluster members
Tune a workload management configuration
Workload management runtime exceptions
Introduction: Clusters


Related


Cluster member settings
Cluster member collection
Server cluster settings
Server cluster collection

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