An SLI is the actual measurement of reliability; the SLO is the target you set on it.
A Service Level Indicator (SLI) is the measured quantity that expresses how well a service is performing, such as the proportion of successful requests or the fraction served under a latency threshold. It is the number an SLO sets a target on.
A good SLI reflects the user's experience and is expressed as a ratio of good events to total events, for example, successful requests over all requests, or requests under 300ms over all requests. Availability, latency, and error rate are the most common. It should move when users are actually affected.
You pick the SLIs that matter for a service, measure them from real telemetry, and set SLO targets on them. The discipline is choosing indicators that correlate with user happiness rather than convenient internal metrics, because you will make trade-offs based on them.
TelemetryOps provides the request-level telemetry from which SLIs are computed, and Sentinel AI acts on the incidents that threaten them.
The percentage of HTTP requests that return successfully, or the percentage served faster than a latency threshold such as 300ms.
The SLI is the measured value; the SLO is the target you set for that value over a window.
Ops Singularity turns open telemetry into autonomous, governed resolution. See it on your own stack.