Capacity planning ensures you have resources before you need them.
Planning process:
Measure current usage and growth rate
Model future demand (organic growth + planned launches)
Identify bottlenecks (CPU, memory, storage, network)
Plan procurement or auto-scaling
Load testing:
- Test at x expected peak
- Identify breaking points
- Plan headroom (-% buffer)
Interview question: "How do you approach capacity planning?"
Start with historical data. Model growth. Add buffer for spikes. Plan lead time for procurement. Set up auto-scaling where possible.