SLI (Service Level Indicator)#
A measured signal such as latency or error rate used to track service health.
Important
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What it is#
A Service Level Indicator (SLI) is a specific, measurable metric that reflects a service’s actual performance against what was agreed or expected — the “thermometer” of how well a service is running. It is the raw measurement used to judge whether a service is meeting its objective.
SLI vs SLO vs SLA#
Three layers stack up. The SLI is the metric measured — “percentage of requests completed within 300 ms”. The SLO is the target for that metric — “99% of requests must complete within 300 ms”. The SLA is the formal contract, often with penalties — “if availability drops below 99%, the provider credits the customer”. SLI is the most granular layer; SLO and SLA build on it.
Common SLIs#
They fall into families: reliability (uptime %, mean time between failures), performance (latency, throughput in requests per second), and quality (error rate, data accuracy). The same idea appears in operations as on-time delivery %, fill rate, or stockout frequency.
An example, and why it matters#
An e-commerce site might measure that 95% of checkout requests finish in under two seconds (the SLI) against an SLO target of 99%, under an SLA that compensates customers if uptime falls below 98%. SLIs matter because they give objective evidence of performance, guide where to improve, and form the measurable foundation of every SLO and SLA.
Theme: MLOps, Serving & Monitoring · All terminology
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Mind map — connected ideas
SLOs (Service Level Objectives) · Model KPIs (Key Performance Indicators) · Monitoring Pipelines · Guardrails (in ML & Data Systems) · Model Stability · ROI (Return on Investment)
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More in MLOps, Serving & Monitoring
AWS SageMaker Endpoints · Caching · Cloud Inference · Cloud Inference with Big Payloads · Compute budgets · Continuous Retraining · Feature Values · Guardrails (in ML & Data Systems) · Inference Cost (Inference $) · Latency Guardrails · Manual review minutes · Model KPIs (Key Performance Indicators) · Model Stability · Monitoring Pipelines
See also
Source article Adapted (context, re-expressed) in our own words from: SLI (Service Level Indicator) (insightful-data-lab.com).