Setting up Service Level Objectives (SLOs) is one of the foundational tasks of Site Reliability Engineering (SRE) practices, giving the SRE team a target against which to evaluate whether or not a service is running reliably enough. The inverse of your SLO is your error budget — how much unreliability you are willing to tolerate.

Whether you’ve heard of or fully jumped on the DevOps or SRE bandwagon, you may have also wondered how the two relate. What’s the difference? Are they really just different ways of looking at the same problem? The term DevOps hit the market first, but SRE wasn’t too far behind. And though they have different origin stories, they both focus on autonomy, automation, and iteration. So why do these paradigms exist? And why do we need both? Let’s look at this further.