Configuring Session-Aware Load Balancing - MACROMEDIA COLDFUSION 4.5-ADMINISTRING COLDFUSION SERVER Manual

Chapter 6: Creating Scalable and Highly Available Web Sites
2. Use your mouse to drag the Peak load threshold line (Red) up or down to reset the
server's Peak load threshold.
As you move the line, the load threshold percentage changes.
3. Enable gradual redirection by selecting the Gradual Redirection checkbox.
4. Drag the Gradual Redirection load threshold line (Yellow) to adjust it accordingly.
5. Close the dialog box.
The load threshold settings you configured are now in effect.

Configuring session-aware load balancing

Managing your Web application's state in a clustered environment can be challenging.
ColdFusion application, session, and server variables that get stored in memory or a
repository during a user session are not persisted by default during a server
redirection. Consequently, the Web server cannot maintain the application's state
correctly.
To overcome this problem, ClusterCATS provides a session-aware load balancing
feature that lets you maintain application state in a clustered environment.
Using session variables and session-aware load balancing
One method for maintaining your ColdFusion Web application's state is to create
session variables that get stored on the Web server. For an e-commerce Web site that is
clustered, it's vital that users do not get redirected to another server in the middle of
their session. If they would, their online transactions would be interrupted, making for
an unsuccessful and frustrating user experience.
To ensure that users are not redirected from the server on which they start their
session, ClusterCATS provides a built-in feature for enabling session-aware load
balancing. Sometimes referred to as "sticky" server, session-aware load balancing
guarantees that users won't get bumped from the server on which they start their
session until the session is complete, regardless of the load thresholds that have been
defined for that server.
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