In cloud service procurement, what is the difference between an SLA and an SLI?

• A. SLA defines service expectations; SLI is a measurable performance indicator
• B. SLA is a data storage standard; SLI is a network protocol
• C. SLA is for on-prem; SLI is for SaaS
• D. SLA is about support availability; SLI about data retention

Answer: (A)

SLA defines the service expectations in a formal agreement, while an SLI is a concrete metric used to measure whether those expectations are being met. In cloud procurement, the SLA outlines what the provider promises—such as uptime, response times, data handling, and remedies when commitments aren’t satisfied. The SLI is the actual measurement that shows how well the service is performing against those promises—think uptime percentage, latency, or error rate.

They work together: the SLA sets the target, and the SLI tracks real performance to determine if the target is achieved. For example, an uptime SLA of 99.9% relies on an SLI that continuously measures uptime to confirm compliance, and if the SLI falls short, the SLA’s remedies or credits can be triggered.

Other options don’t fit because they mischaracterize what SLAs and SLIs represent or apply them inaccurately (such as tying SLAs to data storage standards, network protocols, or limiting them to on-prem or SaaS).