Architecting for Scale

Chapter 5. What Is Risk Management?

All complex systems have risk. It is an inevitable part of all systems. It is impossible to remove all risk from a complex system such as a web application. However, examining your risk and determining how much risk is acceptable is important in keeping your system healthy.

This chapter, provides an overview of what risk is and how we can identify it. It then introduces a process called risk management, which helps us to reduce the effect of risk on our applications.

Let’s now take a look at Example 5-1, which revisits the big game example from Chapter 1.

Example 5-1. Risk management of the big game

Here’s a brief synopsis of the big game example we looked at earlier: it’s Sunday—the day of the big game. You’ve invited friends over to watch it on your new TV. The game is about to start. And…the lights go out and the TV goes dark. The game, for you and your friends is over. You call the power company, and they say “We’re sorry, but we only guarantee 95% availability of our power grid.”

The power company in this example is taking a risk. They are risking that the power won’t go off during a big game.

They even have it quantified (95% likely power will stay on).

The power company knows the types of things that can cause power to go out, such as a power line breaking. As such, to ensure power lines won’t break, they will typically:

• Bury them (to protect them from wind)

• Harden them (to reduce the chance a wind storm can ...