Scalability Rules: 50 Principles for Scaling Web Sites

Martin L. Abbott, Michael T. Fisher

Published by






Reviewed by

Danny Williams MBCS CITP


9 out of 10

Scalability is a challenge that affects many IT systems. Most are designed with a certain capacity in mind. When the limits are reached, the project to add capacity is often far more complex than needs be. There is another way!

This well structured book provides excellent advice on how to design IT systems so that they can scale. It turns out that the reader can apply the rules far more broadly than to websites. Some of the rules are focussed on business-to-consumer applications, but many can be applied in a wide range of circumstances.

The first section is about reducing the equation. I really like this approach, as the simpler the environment the less work should be happening. Less work should aid scalability (as well as performance and other qualities).

Another section promotes scaling out horizontally, which means increasing the number of parallel systems; the alternative is to scale up, where one increases the capacity of a single system. This is an area where I'm not in full agreement with the authors, as there can be merit in scaling up. We do all agree that when scaling up you will eventually reach a hard limit and scaling out is the natural next step.

There is a recurring theme, which is look at scalability in three dimensions. The authors call this the AKF Scale Cube (named after the authors' company - Abbott, Keeven & Fisher Partners). This serves as an excellent point of reference when reviewing the 50 rules.

In addition to now knowing far more about scalability, I find that my understanding of related requirements such as availability and performance has also improved. I would suggest that no non-functional requirement is an island.

If you have a role in the specification, design or build of IT systems then I recommend you read this book. You'll probably already know some of the rules, but I'm sure that even the most experienced IT professional will learn something about scalability.

Further Information: Addison-Wesley

September 2011