SLI / SLO / SLA

Service Level Indicator

A carefully defined quantitative measure of some aspect of the level of service that is provided.

Service Level Objective

A target value or range of values for a service level that is measured by an SLI. A natural structure for SLOs is thus SLI ≤ target, or lower bound ≤ SLI ≤ upper bound.

Service Level Aggrement

The SLA is the entire agreement that specifies what service is to be provided, how it is supported, times, locations, costs, performance, and responsibilities of the parties involved.