Service level objective
A service level objective is a target for a measurable, user-visible property of a service, such as the share of requests that succeed over a period.
What is service level objective?
A service level objective is a target for a measurable, user-visible property of a service, such as the share of requests that succeed over a period.
Plain and technical
An SLO is a specific promise about how reliable a service will be, for example, that 99.9% of requests will succeed over a month. The gap between that target and perfection is how much unreliability you can afford.
An SLO is defined over a service level indicator, a measurement of a user-visible property such as availability or latency. The complement of the objective over the compliance window is the error budget. Tracking budget burn rate is more actionable than instantaneous status, because it indicates whether current behaviour will breach the objective before the window ends.
What it looks like in practice
Nearby vocabulary
Site reliability engineering
Site reliability engineering applies software engineering to operations, using reliability objectives and error budgets to balance stability and speed.
Monitoring
Monitoring is the practice of collecting predefined signals from a system and alerting when they leave their expected ranges.
Observability
Observability is the property of a system that allows its internal state to be understood from the signals it emits, including for failures nobody anticipated.
How DevOpsArk handles service level objective
Articles on this subject
Alerting that people still read at 3am
How to build an alerting system with a high proportion of actionable pages: correlation, ownership routing, suppression, and deleting the rules that never produce a decision.
Monitoring vs observability: a distinction worth keeping
The difference between monitoring and observability, why the distinction is more than marketing, and what each one is actually for.
More definitions
See these concepts in a running system
A 30-minute walkthrough against your own infrastructure rather than a slide about the theory.