Comparison
Error budgetvsError budget policy
Error budget
your SLO allows 0.1 percent failure, you have used 80 percent of that this month, and the risky migration now waits.
The permitted amount of unreliability implied by an SLO, treated as a spendable resource. It reframes reliability as a budget rather than a binary: you are allowed failures, and how you spend them is a choice. Its value is entirely in the policy attached — what actually changes when it is exhausted.
Full entry →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 →