“某网站挂了”，“没有啊，我能访问”。怎样定义合理的 availability 的指标？本文概括了 Google 的 NSDI’20 的论文。
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.