.NET Architecture & System Design Interview Question #190

What is a Service Level Objective (SLO)?

Deployment, Cloud Operations, SRE & Senior System Design Scenarios Senior Advanced

Quick Interview Answer

An SLO is a target value or range for an SLI over a defined period. For example, an API might target 99.9% successful eligible requests during a rolling 30-day window.

Detailed Explanation

An SLO is a target value or range for an SLI over a defined period. For example, an API might target 99.9% successful eligible requests during a rolling 30-day window.

SLOs help teams balance reliability work and feature delivery. The target should reflect user and business requirements rather than automatically demanding 100%, which is often disproportionately expensive.

Code Example

SLI:
request success rate

SLO:
>= 99.9% over 30 days