Performance requirements
are usually identified in terms of transaction response time, number
of transactions per second, throughput, resource utilization, total
cost per transaction, availability, and more. Scalability often refers
to the ability of a component to adapt readily to a greater or lesser
intensity of use, volume, or demand while meeting integral business
objectives. The common objective of scaling a component or system
is to increase the capacity for growth, increase the speed of the
component, improve the efficiency, or shift or reduce the load on
the component.
In order to provide greater performance, scalability, and availability, SAS Web Application
Server supports vertical clustering, horizontal clustering, and a combination of both.
Vertical clusters are multiple web application instances that run on the same machine.
Horizontal clusters are multiple server instances that run on a group of middle-tier
server machines. The SAS Deployment Wizard can be used to automatically configure
a vertical or horizontal
cluster.
When clustering is configured
for the SAS Web Application Server, a load-balancing process distributes
requests among the server instances. Load balancing is automatically
handled by the SAS Web Server. This helps ensure the availability
of the SAS web applications if hardware or software failure occurs.
For more information,
see About Clustering SAS Web Application Servers.