WebSphere Application Server V7.0: Concepts ... - IBM Redbooks

Workload management is a WebSphere facility to provide load balancing and
affinity between nodes in a WebSphere clustered environment. Workload
management can be an important facet of performance. WebSphere uses
workload management to send requests to alternate members of the cluster if
the current member is too busy to process the request in a timely fashion.
WebSphere will route concurrent requests from a user to the same application
server to maintain session state.
WLM for WebSphere for z/OS works differently from the WLM for distributed
platforms. The workload management structure for incoming requests is handled
by the WLM subsystem features of z/OS. Organizations can define
business-oriented rules that are used to classify incoming requests and to assign
service level agreement types of performance goals. This is done on a
transaction level granularity compared to a server level granularity on the
distributed workload management. The system then automatically assigns
resources in terms of processor, memory, and I/O to try to achieve these goals.
In addition to the response times, the system can start additional processes,
called address spaces, that run the user application if there are performance
bottlenecks due to an unpredicted workload spike.
This explanation is an over-simplification of how workload management works in
z/OS. For more information about workload management of z/OS and the
WebSphere Application Server for z/OS refer to 14.1.6, “Workload management
for WebSphere Application Server for z/OS” on page 428, or see the WebSphere
article Understanding WAS for z/OS, available from the following Web page:
http://websphere.sys-con.com/read/98083.htm
242 WebSphere Application Server V7.0: Concepts, Planning, and Design