Describe how you would conduct a capacity planning exercise.
- capacity planning
- scaling
- infrastructure
Answer it first, then compare. Nothing here is saved or scored.
Model answer
Steps: (1) Gather business projections: expected user growth, seasonal peaks, marketing campaigns. (2) Baseline current capacity: max throughput, resource utilization at peak. (3) Model the scaling curve: does performance degrade linearly or exponentially with load? (4) Identify bottlenecks: which component saturates first (CPU, database, network)? (5) Plan scaling strategy: horizontal vs vertical, auto-scaling thresholds. (6) Cost model: infrastructure cost per user at different scales. (7) Validate with load tests at projected capacity. (8) Build headroom: plan for 1.5-2x projected peak.
What interviewers listen for
- Workload modellingYou design the load shape from product traffic, not from tool defaults.
- Percentile literacyYou read p50/p95/p99 separately and explain why each matters.
- Bottleneck triageYou correlate metrics across application, database, and infrastructure layers.
- Capacity instinctsYou can translate a soak test into a sizing or scaling recommendation.