2.1 Introduction

The "oxen story" related in the Preface really provides sufficient justification for why a cluster solution should be considered. Why get a bigger server that will eventually need replacing by an even bigger server when what you really need is an additional server? When it comes to lifting a heavy or bulky load, most of us have no problem getting help and sharing the load. Why is that? Two or more people can safety lift a load too big for one. Think about it. You have a big box, cumbersome and heavy, and you need to lift it. Do you go through your list of friends who are Arnold Schwarzenegger look-alikes to find a single person big enough to lift it for you, or do you find two or more friends who can help?

However, when it comes to computer solutions, increased capacity needs are often met with the "bigger server" approach. Before we leave this example, consider this distinction. When two people (or two oxen) move a load, the load is easier to bear. But, if during the process of moving the load, one of the people falls, the entire job stops! Here is where the computer cluster distinction steps up to the plate. A cluster of computers provides the availability to address the load, even at reduced capacity.

Like the oxen story, clusters solutions, in addition to providing many other benefits, have always been able to meet the load-sharing issues. The initial investment for the cluster...