SLI

A quantitative measurement of service behavior used to evaluate whether an SLO is being met.

Motivation

A quantitative measurement of service behavior used to evaluate whether an SLO is being met.

Where it fits

This concept provides a shared vocabulary for designing, documenting, measuring, or operating software systems.

Mental model

Treat it as a structured tool: define the question being answered, use consistent terminology, and connect the result to decisions and follow-up work.

Subconcepts

Availability SLI

The proportion of valid requests or time windows in which the service is available.

Latency SLI

The proportion of valid requests completed below a defined latency threshold.

Quality SLI

A measure of correctness or degraded behavior when success alone is insufficient.

Practical use

An SLI must define the event population, good-event criteria, measurement source, and aggregation window.

Common mistakes

Using ambiguous definitions or units.
Collecting or documenting information without connecting it to a decision.
Failing to keep the artifact or measurement current as the system changes.

See the linked concepts in the knowledge graph for prerequisites and adjacent practices.