Practice · SLOs and error budgets
What is an SLO and an error budget?
A Service Level Objective is a target for reliability, such as 99.9 percent of requests succeeding over 30 days. The error budget is the small amount of failure that target allows. Tying alert urgency to the error budget means you only get woken when reliability is genuinely at risk.
How to get started with SLOs and error budgets
- 1 Pick one critical user journey and an SLI that measures it, such as the share of requests served under 300 ms.
- 2 Set a realistic target, like 99.9 percent over 30 days, based on current performance.
- 3 Compute the error budget and burn rate continuously.
- 4 Page on fast burn, ticket on slow burn, and use remaining budget to decide release pace.
The common mistake
What is the most common mistake with SLOs and error budgets?
Setting the target at 100 percent or at whatever the system did last month. A target with no budget cannot guide any decision.
See it in action
On-call Resolved calmly
The Page That Never Came
A week on call with zero pages. Not because nothing happened, but because error budgets, symptom-based alerts, and ruthless noise pruning meant only the things worth waking for ever woke anyone.