2 min lesson
Reliability SLIs, SLOs and error budgets
Answer "How does an error budget change behavior compared with a plain SLO target?" Go step by step and end with what you would do.
Step 1 of 3
Engineers on a Performance & Reliability team talk in SLIs, SLOs and error budgets. If you want them to adopt your metric, define it in their language.
The three terms, kept distinct
- SLI
- the measured signal - p99 completion latency, agent success rate
- SLO
- the target you commit to - p99 ≤ 8s for 99% of runs
- Error budget
- the allowed shortfall - the 1% you may spend before you stop shipping
SLI is what you measure, SLO is the promise, error budget is the slack.
The error budget is the part candidates skip and the part that makes the metric powerful. It converts a target into a shipping policy. When the budget is healthy, teams ship fast. When it is spent, the policy says slow down and stabilize. The DS who owns the SLI quietly influences release cadence.