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 within the same sysplex.
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.
- 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.
- 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.