SLI

Overview 3 AM. You get woken up by an alert. You check: CPU normal, memory normal, pods running. But users are complaining the system is unusable. You open Grafana, stare at a wall of charts, and cannot answer one simple question: is this an incident or not? I have encountered this scenario repeatedly across multiple enterprise SRE consulting engagements. The core problem is not insufficient monitoring — it is that the measurement system is designed wrong: we keep monitoring internal system metrics instead of user-perceived service quality....

Overview The first dilemma many teams face when practicing SRE is: they know what an SLO is, but they don’t know how to set one. They either copy Google’s 99.99% or pick an arbitrary 99.9% — only to find that the number neither reflects user experience nor drives engineering decisions. A good SLO isn’t plucked from thin air. It’s derived from business goals through a series of engineering methods: user journey analysis, metric selection, value calibration, multi-tier design, and regular review....