Provision for peak — and prove it.
Capacity Planning: provision for peak
make the invisible limits visible
Always-on capacity wastes money outside spikes.
Capacity planning is taking your traffic forecast plus failure assumptions and producing an infrastructure shape that survives them with margin. Average is a comfortable lie — peaks, spikes, and failure modes are what bring systems down.
Start with peak QPS. For consumer apps, peak is roughly 3–5× average. Black Friday or launch events can be 50× — model these explicitly.
Apply N+1 or N+2 redundancy: if 4 instances handle peak, run 5 or 6 so a single failure leaves you whole. For region-level: keep one region's worth of headroom in another.
Estimate is a hypothesis; load test is the verification. Run synthetic peak through staging and watch p99/p999 — they break long before averages.
Plan capacity for an online ticketing event.