SLO
9% of requests succeed within 300ms over a rolling 28 days' — used to define what 'reliable enough' means for a system and to drive data-driven decisions about when to prioritize reliability work versus new feature development.
10 resources across 2 libraries
Glossary Terms(6)
Service Level Objective (SLO)
A Service Level Objective (SLO) is a specific, measurable reliability target for a service — such as '99.9% of requests succeed in under 300ms over 30 days' —…
Autoscaling
Autoscaling is the automated adjustment of compute resources — adding or removing instances, containers, or pods — in response to real-time demand, load, or de…
Cold Start
A cold start is the added latency incurred when a serverless function, container, or newly-scaled instance must be initialized from scratch — provisioning reso…
Availability Zone
An availability zone (AZ) is one or more physically separate data centers within a cloud region, each with independent power, cooling, and networking, designed…
Observability Pipeline
An observability pipeline is the infrastructure that collects, processes, routes, and stores telemetry data — logs, metrics, and traces — from applications and…
SLO
An SLO (Service Level Objective) is a specific, measurable target for a service's reliability — such as '99.9% of requests succeed within 300ms over a rolling…
Interview Questions(4)
SLA vs SLO vs SLI: What Is the Difference?
An SLI (Service Level Indicator) is a measured metric like request latency or error rate, an SLO (Service Level Objective) is the internal target you set for t…
Why Does Tail Latency (p99) Matter More Than Average Latency?
Tail latency (measured as p95, p99, or p999 percentiles) matters more than average latency because a system with a low average can still have a meaningful frac…
What Are SLIs, SLOs, and SLAs?
An SLI (Service Level Indicator) is a measured metric of user-facing performance like request success rate, an SLO (Service Level Objective) is the internal ta…
What is an Error Budget?
An error budget is the allowed amount of unreliability a service can accumulate before breaching its SLO, calculated as 100% minus the SLO target over the meas…