Some IT shops cringe at the thought of introducing "clustering" into their data centers. The term conjures up images of complex technologies interwoven to create an environment that's too fragile to be touched and too complicated to be understood. Yet some organizations have found that clustering enables their IT staff to spend nights at home and weekends at the beach. What is it about clustering that makes it a risk that some IT organizations are willing to take?

It's all about availability. Some companies need their enterprise resource planning (ERP) applications to be up and running 24/7. Clustering an IT infrastructure can increase availability and help IT make changes with less risk to application downtime. However, the availability of a business function isn't achieved through the implementation of a single product; rather, increased availability is woven into the fabric of the data center. There are common and not-so-common techniques to increase an application's availability through clustering. But while clustering can increase the availability of an application, it doesn't necessarily increase the availability of a business function.