The Art of Capacity Planning

Chapter 1. Goals, Issues, and Processes in Capacity Planning

THIS CHAPTER IS DESIGNED TO HELP YOU ASSEMBLE AND USE THE WEALTH OF TOOLS AND TECHNIQUES presented in the following chapters. If you do not grasp the concepts introduced in this chapter, reading the remainder of this book will be like setting out on the open ocean without knowing how to use a compass, sextant, or GPS device—you can go around in circles forever.

When you break them down, capacity planning and management—the steps taken to organize the resources your site needs to run properly—are, in fact, simple processes. You begin by asking the question: what performance do you need from your website?

First, define the application’s overall load and capacity requirements using specific metrics, such as response times, consumable capacity, and peak-driven processing. Peak-driven processing is the workload experienced by your application’s resources (web servers, databases, etc.) during peak usage. The process, illustrated in Figure 1-1, involves answering these questions:

1. How well is the current infrastructure working?

   Measure the characteristics of the workload for each piece of the architecture that comprises your applications—web server, database server, network, and so on—and compare them to what you came up with for your performance requirements mentioned above.

2. What do you need in the future to maintain acceptable performance?

   Predict the future based on what you know about past system performance then marry that prediction ...