CodeParkAn SLI is what you measure. An SLO is your internal target for it. An SLA is a contract with customers. A 99.9% monthly SLO allows about 43 minutes of downtime.
- An SLI (service level indicator) is a measured number that shows service health. Example: the share of requests that succeed in under 300 ms.
- An SLO (service level objective) is the internal target for that SLI over a time window. Example: 99.9% over 30 days.
- An SLA (service level agreement) is a contract with customers. It states what happens if you miss a level, such as giving credits. It is normally looser than the SLO. This way, you get a warning before you break the contract.
The error budget is 1 minus the SLO. Here it is 0.1%. Over 30 days, that is about 43 minutes of full downtime (30 x 24 x 60 x 0.001 = 43.2).
How teams use it:
- While budget remains, teams ship features and take risks.
- When the budget is used up, they slow down releases and focus on reliability.
This turns reliability into an agreed, measurable trade-off with how fast you ship features.
- An SLI is the thing you measure.
- An SLO is the internal target for the SLI.
- An SLA is an external contract with penalties, and it is looser than the SLO.
- The error budget is 1 - SLO, which is about 43 min per month at 99.9%.
- With budget left, ship features. With budget spent, focus on reliability.