Observability · Cluster
SLO Practice
Objectives, error budgets, and policy.
- 01 The SLI Ratio: Numerator, Denominator, and Measurement Point Why an availability target fixes nothing until the fraction behind it is defined, and how moving the counting location changes the reported number.
- 02 Error Budget Units: Why Burn Rate Beats Remaining Budget How a budget derived from a target becomes a rate, why the rate is comparable across services with different targets, and where the arithmetic breaks at low volume.
- 03 Objective Windows: Rolling Windows, Calendar Months, and Time Equivalence How the choice of measurement window changes what a target means, why a 28-day window is the conventional default, and how to convert a time-based target into a count-based one.
- 04 Multiwindow Burn-Rate Alerts and Why a Short Window Also Suppresses How pairing a long lookback with a short confirmation window yields both fast detection and durable alerts, and what the boolean pairing costs in edge cases.
- 05 Deriving Latency Targets from Percentile Distributions Why a percentile objective is really a tail-count budget, how bucket layout limits the achievable precision, and what a latency target costs in headroom.
- 06 Low-Volume Objectives and the Distortion of Counting Qualifiers Why a 99.9% target on a few hundred requests a day cannot be estimated from the data, and how qualifier counting and aggregation windows change the answer.
- 07 Error Budget Policy: Freezes, Exemptions, and Escalation Arithmetic How a budget becomes an enforceable rule, why a freeze that everyone can override is worse than none, and how exemption quotas are computed from the budget itself.
- 08 Dependency Objectives: Propagating Budgets Across a Call Graph How a caller composes its own objective from the objectives of services it depends on, and why consistent fan-out makes end-to-end targets arithmetically impossible.
- 09 Composite Objectives: Compressing Multi-Signal Health into a Single Score How normalization, weighting, and aggregation order determine what a composite objective means, and why the same weights can hide opposite failure patterns.
- 10 Attribution, Turnover, and the Latent Measurement Error in Objectives Why an indicator drifts away from the state it claims to measure as schemas, traffic mixes, and instrumentation change, and how to detect the drift.