· book review

The Case for DevOps: A Summary of Accelerate

During my travels as a developer, I find myself having the following conversations far too often. Have you seen any of these?

Timid Developer: “I’d like to do unit tests on my project, but my boss won’t let me. He said we don’t have enough time to do them.”

Me: “You shouldn’t be asking your boss to do unit tests, just do them.”


Beleaguered Developer: “I’d like to adopt modern development practices at my organization, but we’re not a software company, so we can’t adopt the latest practices.”

Me: “Every company is a software company, especially the insurance company you’re at now.”


Obstinate Developer: “Why should we adopt <insert modern development practice>? Why can’t we just do it the old way?”

Me: “<facepalm>”

I wish there were a book that I could throw at people that would use science to show the value of modern development practices. It turns out, this book exists, and it’s called Accelerate: The Science of Lean Software and DevOps: Building and Scaling High Performing Technology Organizations.

The authors, Jez Humble and Gene Kim, are behind other great DevOps books like The Phoenix Project and the DevOps Handbook. Their previous books focused on how to do DevOps, but they wondered how much these practices helped organizations.

To do this, they turned to organizational scientist Nicole Forsgren, Ph.D. She applied academic research methods to determine which development practices make things better. Accelerate comes from their research from 2014 to 2017. Between the three of them, they make a strong case for modern DevOps practices.


The results from this book come from studying over 2,000 organizations over four years. A whole section is devoted to the various research methods they used and why they work. For our purposes, I want to focus on the metrics they used to evaluate performance.

Measuring software delivery is difficult. Some measures of delivery, like lines of code, have obvious problems. Using lines of code as your engineering performance metric is like using airplane weight. More is not necessarily better.

Other measures have less apparent problems. In many organizations, you have two different areas in IT, software development and operations. Managers often measure the departments in different ways. They evaluate developers by the features they deliver. Operations folks are assessed by how stable they make the environment. These different goals create a perverse incentive structure where software developers throw difficult to deploy code over a wall and ops slows them down with a maze-like change management process.

To effectively measure performance, you need metrics for the whole process, not just specific teams. Use global metrics to get everyone on the same page. In Accelerate, they settled on four primary metrics.

Deployment frequency
Small batches delivered often are ideal.

Delivery Lead Time
Overall lead time can be difficult to measure due to the “fuzzy front end” (ideation, requirements gathering, etc…). Delivery lead time measures the time from commit to deploy.

Mean recovery Time
Bad things happen. How long does it take to fix them?

Change Failure Rate
How many changes fail? Smaller changes generally mean fewer of them fail.


When evaluating the performance of an organization, people often use maturity models. Each aspect of software delivery is assessed based on a target. Once you hit that target, your organization is “mature” in that category. Unfortunately, that thinking doesn’t work. We build software and the landscape we’re in changes constantly. There’s no such thing as “maturity” when tools shift every 5-10 years.

Instead of looking at maturity, evaluate capabilities. In Accelerate, they identified several organizational capabilities that lead to increased business performance.

Capabilities for Improvement

  • Version Control
  • Trunk Based Development
  • Test Automation
  • Shifting Left on Security
  • Continuous Delivery
  • Loosely Coupled Architectures
  • Empowered Teams
  • Seeking Customer Feedback
  • Working in small batches
  • Team Experimentation
  • Lightweight Change Approval Processes
  • Monitoring / Proactive Notification
  • WIP Limits
  • Visualizing Work
  • Westrum Organizational Model
  • Supporting Learning

Your organization is probably using many of these practices today, but most organizations have not mastered them all. You can continue to improve in all these realms. The research in Accelerate showed that the top organizations were continuing to grow. They didn’t hit “maturity” and stop. They continually develop to get even better at software delivery.


Accelerate is chock full of statistics, but here are a few of the most impactful ones. The company divided companies into three categories (high, medium, low) based on their performance. They then measured some of the differences between the groups.

High performers vs. Low Performers: Software Delivery
46 times as many code deployments
440 times as fast commit to deployment time
170 times faster mean time to recover
5 times lower change failure rate

High performers vs. Low Performers: Org Performance
2x as likely to exceed organizational objectives: profitability, productivity, market share
2x as likely to exceed noncommercial goals like customer satisfaction
50% higher growth over three years
Employees are 2.2 more likely to recommend their organization as a great place to work


While most of this book confirmed things I already knew about, there were a few surprises. The biggest surprise for me was that organizations that were in the middle frequently had high error rates than either lower performing or high performing organizations. They refer to it in the book as the “j-curve”. It makes sense that there are some growing pains associated with adopting new practices, and it indicates promoters of dev ops practices need to communicate that gap when trying to move their organizations forward. Wary organizations might backslide if they perceive the changes are having an adverse effect.

The reality is that speed and quality positively correlate. Software development is about tradeoffs, but this isn’t one you have to make. You can have a screaming fast release process and have a lower change failure rate. A big part of the magic here is working in small batches. Small batches are easier to understand, which makes it easier to develop and test.

Another big surprise was the emphasis on trunk-based development over other branching workflows. More involved styles like git-flow are suitable for large open source projects, but for most folks, it pays to keep it simple.

We all know that automated testing is essential, but it turns out that those automated tests have a far greater value when they are written and maintained by the developers. This doesn’t mean that we need to get rid of QA folks. They perform valuable and important work. What doesn’t work is throwing your code over the wall to a testing department that may or may not have automated regression testing. You need to build your tests on a cross-functional team where the developers and QA folks can work together to create automated tests. These tests need to be useable by everyone, including by developers on their machines.

There’s this idea in software development that to use the latest processes, you need to have access to the latest tools. People who aren’t using the latest and greatest technologies need not apply. The authors of Accelerate didn’t just focus on cutting edge organizations; they looked at all sorts of organizations using all sorts of processesThis including companies running on mainframes and companies still using waterfall-style processes. They found that all companies benefit from DevOps practices, even ones running on older technologies. While using newer technologies can help, there are no excuses for not moving forward.

Who Should Read This Book?

This book is excellent for anyone who needs a persuasive argument for adopting DevOps practicesThis including managers, consultants, and coaches. Additionally, developers and other delivery folks may find this interesting. If you’re looking for more of a how-to than a why-to, then skip this book and get yourself a copy of the Dev Ops Handbook.

A Case for Modern Delivery Practices

As we continue to evolve the way we build software, it’s important to understand why these changes matter. Accelerate shows us, scientifically, why modern practices matter and how they can create better-performing organizations with happier employees.

Back to Blog