Meaningful availability
This very clearly written paper describes the Google G Suite team’s search for a meaningful availability metric: one that accurately reflected what their end users experienced, and that could be used by engineers to pinpoint issues and guide improvements.
A good availability metric should be meaningful, proportional, and actionable. By “meaningful” we mean that it should capture what users experience. By “proportional” we mean that a change in the metric should be proportional to the change in user-perceived availability. By “actionable” we mean that the metric should give system owners insight into why availability for a period was low. This paper shows that none of the commonly used metrics satisfy these requirements…
The alternative that Google settled on is called windowed user-uptime and it’s been used in production across all of G Suite for the past year. We’ll look at how windowed user-uptime works in a moment, but first let’s review commonly used approaches to availability reporting and why they failed Google’s test.
