Architecting for Scale

Chapter 10. Building Systems with Reduced Risk

In Chapter 8, we learned how to mitigate risks that exist within your system and applications. However, there are things you can do to proactively build your applications with a reduced risk profile. This chapter reviews a few of these techniques. This is far from an exhaustive list, but it should at least get you thinking about risk reduction as you build and grow your applications.

Redundancy

Building in redundancy is an obvious step to improving the availability and reliability of your application. This inherently reduces your risk profile as well. However, redundancy can add complexity to an application, which can increase the risk to your application. So, it is important to control the complexity of the additional redundancy to actually have a measurable improvement to your risk profile.

Here are some examples of “safe” redundancy improvements:

• Design your application so that it can safely run on multiple independent hardware components simultaneously (such as parallel servers or redundant data centers).

• Design your application so that you can run tasks independently. This can help recovery from failed resources without necessarily adding significantly to the complexity of the application.

• Design your application so that you can run tasks asynchronously. This makes it possible for tasks to be queued and executed later, without impacting the main application processing.

• Localize state into specific areas. This can ...