SRE6 min read
SLOs vs SLIs vs SLAs
Three acronyms that are often used interchangeably. They shouldn't be.
SLI — the measurement
A service level indicator is a quantitative measure of some aspect of the service as users experience it, such as the proportion of successful requests or requests served under a latency threshold.
SLO — the target
A service level objective is an internal target for an SLI over a time window. It defines 'reliable enough' and is the basis for error budgets.
SLA — the contract
A service level agreement is an external commitment, usually with consequences. SLAs should be looser than SLOs so teams have room to react before breaching a contract.