Monitoring
Error Budget
An error budget is the acceptable amount of unreliability inside an SLO — 1 minus the objective. A 99.9% SLO means 0.1% of requests can fail without breaching. That 0.1% is the budget the team can spend on deploys, experiments, and controlled risk.
In depth
Error budgets convert reliability from a wish into a currency. Each unavailability event, latency breach, or deploy-related regression spends budget. When the budget is healthy, teams can ship aggressively. When it is depleted, deploys freeze and every engineer focuses on reliability work until the budget recovers.
The standard implementation uses a rolling 28- or 30-day window with burn-rate alerts: a fast burn (10% of monthly budget in an hour) pages the on-call; a slow burn (25% over a day) opens a ticket.
Why it matters
Error budgets end the eternal fight between product and SRE. Instead of 'stop shipping so much' vs 'stop being paranoid', the team follows the number. Fast, sustainable, and shared.
Related terms
Service Level Objective
SLO means Service Level Objective — the internal reliability target a team commits to, such as 99.9% of homepa…
Service Level Indicator
A Service Level Indicator (SLI) is the actual measurement of one aspect of service — usually availability, lat…
SLA
A service level agreement (SLA) is a contractual commitment between a provider and a customer specifying a mea…
Incident
An incident is a confirmed period of degraded or unavailable service that requires human attention. Incidents …
Synthetic Monitoring
Synthetic monitoring is the practice of running scripted, scheduled checks against a website from controlled p…
Browse the full Lemwatch monitoring glossary (47 terms).