SLO
Service Level Objective. A measurable reliability target for a service defined over a time window.
Definition
An SLO (Service Level Objective) is the target you want to hit for an SLI.
It is defined over a time window.
Example: 99.9% success rate over 30 days.
A concrete example
If your SLI is “successful checkout requests,” an SLO could be:
- 99.95% successful checkouts over 30 days.
This is a statement you can measure and alert on.
Why it matters
SLOs make tradeoffs honest.
They are how you justify engineering work in terms of user impact.