SLI (Service Level Indicator)
A Service Level Indicator (SLI) is the actual measured value of a reliability metric — the number you compare against your SLO and SLA.
An SLI is a concrete measurement: the percentage of successful requests, the fraction of checks under a response-time threshold, or availability over a window. It is the ground truth that SLOs and SLAs are judged against.
Choosing good SLIs matters — they should reflect what users actually care about (does the page load, is it fast enough) rather than internal proxies that look healthy while users suffer.
Related terms
SLO (Service Level Objective)A Service Level Objective (SLO) is an internal target for a reliability metric — for example SLA (Service Level Agreement)A Service Level Agreement (SLA) is a contractual commitment to a level of service — most commonly a guaranteed uptime percentage — with consequences if it is missed.Response TimeResponse time is how long a service takes to respond to a request, usually measured in milliseconds.
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