In this article, I'll introduce you to the concept of server clustering. As I do, I'll discuss some of the issues that you need to consider when planning a cluster. By doing so, client machines see the service or application processed by the cluster as though it were coming from a single machine. This means that if you've got an application that requires two servers today, you can simply bring another server online tomorrow when demand on the application grows. Any time your application starts to bog down, you can plug in another server and watch the application's performance improve.
Clustered servers offer high availability.
For example, suppose you had a cluster of three servers running a critical business application. Now, imagine that one of the servers experienced a critical failure. In the old days, your application would have been down for the count, and your business wouldn't have been able to function until the server was brought back up. In a cluster environment, the two servers still running detect the failure and adjust themselves to pick up some of the slack. When the problem server is repaired, it can be brought back on line and resume its old workload.