SLI, SLO & SLA Vocabulary
5 exercises — Master the language of the SLI/SLO/SLA hierarchy, error budget calculation, and reliability target communication.
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An SRE is explaining the reliability measurement system to a new team member. They say: "We measure availability using request success rate as our ___, we set a 99.9% target as our ___, and the contractual commitment with enterprise customers is the ___." Choose the correct order.
SLI → SLO → SLA is the correct hierarchy.
SLI (Service Level Indicator) is the measured metric — e.g., "99.95% of requests returned a 2xx response in the last 30 days."
SLO (Service Level Objective) is the internal target for that indicator — e.g., "We aim to keep the SLI above 99.9%."
SLA (Service Level Agreement) is the external contractual commitment — e.g., "Enterprise customers are guaranteed 99.5% availability with financial penalties for breach."
Key vocabulary:
• SLI — the actual measured value; always a ratio or percentage
• SLO — internal reliability target; slightly tighter than the SLA
• SLA — legal/commercial commitment to customers
• SLO tighter than SLA — intentional buffer so internal violations don't immediately breach the customer contract
SLI (Service Level Indicator) is the measured metric — e.g., "99.95% of requests returned a 2xx response in the last 30 days."
SLO (Service Level Objective) is the internal target for that indicator — e.g., "We aim to keep the SLI above 99.9%."
SLA (Service Level Agreement) is the external contractual commitment — e.g., "Enterprise customers are guaranteed 99.5% availability with financial penalties for breach."
Key vocabulary:
• SLI — the actual measured value; always a ratio or percentage
• SLO — internal reliability target; slightly tighter than the SLA
• SLA — legal/commercial commitment to customers
• SLO tighter than SLA — intentional buffer so internal violations don't immediately breach the customer contract