Vertical scaling topology
Vertical scaling refers to setting up multiple application
servers on one machine, usually by creating cluster members.

This topology illustrates a simple vertical scaling example, with multiple
cluster members of an Application Server on Machine A. You can also implement
vertical scaling on more than one machine in a configuration. Combine vertical
scaling with other topologies to boost performance and throughput.
Typical use
Vertical scaling offers the following advantages:
- Increased processing power efficiency. An instance of an application
server runs in a single Java virtual machine (JVM) process. However, the inherent
concurrency limitations of a JVM process prevent it from fully utilizing the
processing power of a machine. Creating additional JVM processes provides
multiple thread pools, each corresponding to the JVM process associated with
each Application Server process. This correspondence avoids concurrency limitations
and lets the Application Server use the full processing power of the machine.
- Load balancing. Vertical scaling topologies can use the WebSphere
Application Server workload management facility.
- Process failover. A vertical scaling topology also provides failover
support among Application Server cluster members. If one Application Server
instance goes offline, the other instances on the machine continue to process
client requests.
Single machine vertical scaling topologies have the drawback of introducing
the host machine as a single point of failure in the system. Vertical scaling
on multiple machines avoids the single point of failure.
Instructions
To set up a vertical scaling topology, use the administrative console to
configure a set of Application Server cluster members that reside on the same
machine.
It is recommended that you plan vertical scaling configurations ahead of
time. However, because vertical scaling does not require any special installation
steps, you can implement vertical scaling whenever it is needed.
While you are deciding how many cluster members to create on a machine,
take these factors into account:
- The design of the application. Applications that use more components
require more memory, limiting the number of cluster members you can run on
a machine.
- The hardware environment. Vertical scaling works best with plenty
of memory and processing power. Eventually there is a point of diminishing
returns on any machine, where the overhead of running more cluster members
cancels out the benefits of adding them.
The best way to ensure good performance in a vertical scaling configuration
is to tune a single instance of an Application Server for throughput and performance,
then incrementally add cluster members. Test performance and throughput as
you add each cluster member. Always monitor memory use when you are configuring
a vertical scaling topology, so you do not exceed available physical memory
on the machine.

Setting up a multinode environment
Searchable topic ID:
cins_vertscale
Last updated: Jun 21, 2007 8:07:48 PM CDT
WebSphere Business Integration Server Foundation, Version 5.0.2
http://publib.boulder.ibm.com/infocenter/wasinfo/index.jsp?topic=/com.ibm.wasee.doc/info/ee/ae/ctop_vertscale.html