SLO Review & Adjustment Language
5 exercises — Practice the English for conducting SLO reviews, deciding when to tighten or relax targets, and using data as evidence for changes.
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Quick reference: SLO review signals
- >80% budget remaining → SLO may be too loose; consider tightening
- 20–70% budget used → SLO is well-calibrated; maintain
- <20% remaining → investigate; may need reliability investment before relaxing
- Agree on criteria before reviewing data → prevents confirmation bias
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An SRE lead opens the quarterly SLO review with: "Let's look at the data from the past three months and decide whether to tighten, relax, or maintain each SLO." Under what condition would it be appropriate to tighten an SLO?
The quarterly SLO review uses budget consumption as the primary signal for adjusting targets.
Decision framework:
• Budget mostly unused (>80% remaining) → the SLO may be too loose; consider tightening
• Budget partially consumed (20–70% used) → the SLO is well-calibrated; maintain
• Budget nearly exhausted (<20% remaining) → the SLO may be aspirational; investigate before relaxing
Tightening an SLO when you have headroom signals commitment to users and raises the bar — but should be done incrementally (e.g., 99.9% → 99.95%, not 99.9% → 99.99%).
Key vocabulary:
• SLO review — periodic (quarterly) assessment of whether SLO targets are still appropriate
• Tightening the SLO — raising the reliability target
• Relaxing the SLO — lowering the reliability target (requires stakeholder agreement)
• SLO ratchet — the pattern of incrementally tightening SLOs as reliability improves
Decision framework:
• Budget mostly unused (>80% remaining) → the SLO may be too loose; consider tightening
• Budget partially consumed (20–70% used) → the SLO is well-calibrated; maintain
• Budget nearly exhausted (<20% remaining) → the SLO may be aspirational; investigate before relaxing
Tightening an SLO when you have headroom signals commitment to users and raises the bar — but should be done incrementally (e.g., 99.9% → 99.95%, not 99.9% → 99.99%).
Key vocabulary:
• SLO review — periodic (quarterly) assessment of whether SLO targets are still appropriate
• Tightening the SLO — raising the reliability target
• Relaxing the SLO — lowering the reliability target (requires stakeholder agreement)
• SLO ratchet — the pattern of incrementally tightening SLOs as reliability improves