SLA vs SLO vs SLI
To dive into the terms throughly, it’s better to read Google SRE Book. This post is just a glance.
TL;DR⌗
SLIs drive SLOs which inform SLAs. (From Google SRE Team)
SLA: Service Level Agreements⌗
An SLA is an agreement between provider and client about measurable metrics like uptime, responsiveness, and responsibilities.
SRE doesn’t typically get involved in constructing SLAs, because SLAs are closely tied to business and product decisions.
e.g. Service credit if 95th percentile homepage SLI succeeds less than 99.5% over tailing year
SLO: Service Level Objectives⌗
An SLO is an agreement within an SLA about a specific metric like uptime or response time.
Choosing an appropriate SLO is complex.
e.g. 95th percentile homepage SLI will succeed 99.9% over trailing year
SLI: Service Level Indicator⌗
An SLI measures compliance with an SLO (service level objective).
Most services consider request latency—how long it takes to return a response to a request—as a key SLI. Other common SLIs include the error rate, often expressed as a fraction of all requests received, and system throughput, typically measured in requests per second.
e.g. 95th percentile latency of homepage requests over past 5 minutes < 300ms
Teams Cooperation⌗
