What is SLI and SLO?
Turkish: SLI ve SLO (Hizmet Seviyesi Göstergeleri)
SLIs and SLOs define measurable service signals and the reliability targets teams commit to for those signals over time.
What is SLI and SLO?
An SLI (Service Level Indicator) is the signal being measured; an SLO (Service Level Objective) is the target for that signal. For example, “successful request rate” is an SLI, while “99.9% of requests should succeed over the last 30 days” is an SLO.
An SLI should be close to user experience. Server CPU is measurable, but a customer usually cares more about whether a checkout request succeeds within an acceptable time. Common SLIs include availability, latency, error rate, data freshness, and transaction correctness.
Difference from SLA
An SLA is usually a contract with a customer or supplier; an SLO is the reliability target a team manages internally. When an SLO is missed, the error budget is consumed, and the team may shift attention from new features to stability work. Uptime is only one possible signal in that calculation.
Good SLI/SLO design is fed by observability data and avoids defining too many targets. Setting a separate objective for every endpoint can become unmanageable. It is usually better to focus on flows with high revenue, customer experience, or operational risk.
Related Terms
Observability is the ability to understand a system's internal state from its external outputs (logs, metrics, traces) — a key DevOps principle.
SLA (Service Level Agreement)An SLA defines uptime, response time, resolution targets, measurement methods, and remedies between a provider and a customer.
Site Reliability Engineering (SRE)SRE applies software engineering to reliability work, including automation, incident response, capacity planning, and service targets.
UptimeUptime expresses how long a system remains accessible outside planned or unplanned outages, usually as a percentage or time window.