SLI

Definitions

1. Service Level Indicator — a carefully chosen metric that quantitatively measures some aspect of a service's reliability, such as request latency, error rate, or throughput. SLIs are the raw measurements against which SLOs are evaluated. Good SLIs capture the user's experience, not just internal system health.

   In plain English: The actual measurement that tells you how well your service is performing — the real number you compare against your reliability goal.

   Example: Our primary SLI is the percentage of requests that complete in under 200ms, measured at the load balancer — not at the application, where network latency is invisible.

Related Terms

• SLA
• Nines
• SLO
• service mesh
• error budget
• Five Nines
• Incident Management