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

Availability
The concept of a separate servant and control region greatly enhances the
availability of a user application.
► Multiple servant regions can form a kind of vertical cluster running your
application. In the case that one servant region goes down, users with in-flight
transactions in that servant will receive an error. The other servant regions will
continue to work and respond to requests, so the overall application is still
available and new requests can enter the system. z/OS will automatically
re-launch the failed servant.
► The control region might be identified as a single point of failure. Although the
control region is unique per application server, the risk of failure is low. Only
WebSphere Application Server for z/OS product code is executed in this
region. To remain available with your application, keep in mind that it is also
possible to create a WebSphere Application Server cluster, as in an
distributed environment.
Performance
From a performance point of view the concept of different regions and the usage
of WLM greatly enhances performance and scalability.
► Performance improvements are achieved by creating multiple servant
regions, because more requests can be processed in parallel if the system
has enough resources available.
► You can set detailed performance targets on a transactional level for the
response time. The system will automatically adjust resources on a 7x24x365
basis, to make sure that these goals are kept.
► Through the usage of multiple JVMs with smaller heaps, the penalty a single
transaction has to pay during garbage collection, will decrease and general
throughput will increase.
14.2 What is new in V7.0
WebSphere Application Server V7.0 in general offers some new concepts,
functions, and features. Refer to Chapter 3, “WebSphere Application Server
concepts” on page 51 for an overview of these concepts, functions, and features.
432 WebSphere Application Server V7.0: Concepts, Planning, and Design