Chapter 22. Clustering

You cannot eat a cluster of grapes at once, but it is very easy if you eat them one by one.

—Jacques Roumain

The word “clustering” can mean different things to different people. Some people would say clustering is simply having a replicated system on standby available to be turned on when the primary system fails. To others, clustering is having several systems working in concert with one another, with replicated data, fully redundant, and infinitely expandable. For most people, it’s probably somewhere between those two extremes.