The Site Reliability Workbook

Chapter 3. SLO Engineering Case Studies

By Ben McCormack (Evernote) and William Bonnell (The Home Depot) with Garrett Plasky (Evernote), Alex Hidalgo, Betsy Beyer, and Dave Rensin

While many tenets of SRE were shaped within the walls of Google, its principles have long lived outside our gates. Many standard Google SRE practices have been discovered in parallel or otherwise been adopted by many other organizations across the industry.

SLOs are fundamental to the SRE model. Since we launched the Customer Reliability Engineering (CRE) team—a group of experienced SREs who help Google Cloud Platform (GCP) customers build more reliable services—almost every customer interaction starts and ends with SLOs.

Here we present two stories, told by two very different companies, that outline their journeys toward adopting an SLO and error budget–based approach while working with the Google CRE team. For a more general discussion about SLOs and error budgets, see Chapter 2 in this book, and Chapter 3 in our first book.

Evernote’s SLO Story

by Ben McCormack, Evernote

Evernote is a cross-platform app that helps individuals and teams create, assemble, and share information. With more than 220 million users worldwide, we store over 12 billion pieces of information—a mix of text-based notes, files, and attachments/images—within the platform. Behind the scenes, the Evernote service is supported by 750+ MySQL instances.

We introduced the concept of SLOs to Evernote as part of a much wider technology ...