SLO

Definition

Service Level Objectives (SLOs) are quantitative targets that define the acceptable level of service reliability and performance a system should deliver to its users. They provide clear, measurable standards for system quality and are typically expressed as a percentage over a rolling time window.

In depth

SLOs are built on the concept of an error budget — the allowable amount of unreliability within the SLO window. If your SLO is 99.9% availability over 30 days, your error budget is 43.2 minutes of downtime. Error budgets acknowledge that perfect availability is neither achievable nor necessary, and they give engineering teams a data-driven framework for deciding when to ship new features (budget intact) vs. when to focus on reliability work (budget depleted). SLOs sit between an SLA (a legal contract with customers) and an SLI (a metric that measures the SLO). obseria.io includes SLO management with burn-rate alerts that warn teams when error budget is being consumed faster than expected.

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