Comparison
Error budget policyvsService level objective
Error budget policy
the budget was spent in the first week of the quarter, and feature work stopped until reliability caught up.
The agreement, made in advance, about what happens when the error budget implied by an objective is exhausted. Without it an error budget is a dashboard; with it, it is a pre-negotiated answer to the reliability-versus-features argument that would otherwise be had under pressure and won by whoever is loudest. The policy is the product — the number was never the point.
Full entry →Service level objective
you commit internally to 99.9 percent of requests succeeding over 30 days, and you now have a number that says when to stop shipping features.
A target for an SLI over a time window. Its real function is decision-making: it converts "is reliability good enough" from an argument into arithmetic. An SLO nobody is willing to act on — by slowing releases or prioritising reliability work — is a dashboard, not an objective.
Full entry →