What is SLA, SLI and SLO's?

SLA - Service level agreement.

SLA basically means a Service Level Agreement. It’s a formal agreement or a legal contract between you and your customers. It basically describes the reliability of your product/service in a formal agreement.

An example of this would be - our product will be online 99 percent of the time annually and if we fail to achieve that objective we will give 30% of your annual license fee back.

SLA’s also include penalties in the contract. That means if you fail to meet a certain level of reliability you basically do something for your customers.

SLO - Service level objective.

Before we go on to SLO’s, SLA’s is a contract that includes a lot of components like it might include the reliability of an API, Home Page, Dashboard, etc. Each of these components has the reliability objectives that you want to achieve.

An example of this would be - API will be up 99.99% of the time and the error rate of the API will be less than 0.01 percent in a year.

SLO’s basically describes the reliability goal of a particular resource in your organization or in your product. Think of these as your internal objectives to meet your formal SLA.

SLI - Service level indicator.

SLI stands for service level indicator. It’s the status of your resources over a period of time. This is what monitoring tools tells you.

This basically answers the question – What’s the uptime % of my API this quarter or this year.

Conclusion

SLA is the legal contract with your customers. SLO is your internal goal. SLI is how has your resource actually been performing over a period of time.