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.
In more complex workload management scenarios, you can distribute
cluster members to remote machines.
About this task
Perform the following steps if you decide to use clusters to balance
your workload.
Procedure
- Decide which application server you want to cluster.
- 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.
- Deploy the application onto the application server.
- 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.
- Create one or more cluster members.
- Configure a backup cluster.
A
backup cluster handles requests if the primary cluster fails.
- 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.
- 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. 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 com.ibm.websphere.wlm.unusable.interval property.
What to do next
For stand-alone Java clients, you must
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.