SLA chain calculator
End-to-end availability of a request path. Each row is one hop; add instances where a component scales horizontally.
End-to-end availability
- Downtime per day
- Downtime per week
- Downtime per month
- Downtime per year
No hops yet. Add the first component a request passes through.
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Weakest hop%
How it works
Serial hops. Every hop must be up, so availabilities multiply: A = A₁ × A₂ × … × Aₙ. The chain is always worse than its weakest hop.
Redundant instances. A hop is down only when all its instances are down at once: A = 1 − (1−a₁)(1−a₂)…
Assumptions. Instances fail independently, one healthy instance can carry the full load, and failover is instant. Shared causes such as a common region, deploy or database make real numbers lower.