Forecast Storage Demand Across 100 Data Centers

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Quick Overview

Forecast daily storage demand for one data center, scale models to 100 sites, and handle new-site cold starts with shared information and uncertainty.

Forecast Storage Demand Across 100 Data Centers

Company: Apple

Role: Machine Learning Engineer

Category: ML System Design

Difficulty: medium

Interview Round: Technical Screen

Design a forecasting approach for daily data-center storage demand. Explain how you would begin with one data center, extend the approach to 100 data centers, and produce forecasts for a newly established data center with little or no history. ### Part 1 — Forecast one data center Define the target and forecasting horizon, then describe the data, baseline, model, and evaluation method. #### What This Part Should Cover - The distinction between new storage demand, net growth, and occupied capacity. - Seasonality, known future information, and chronological evaluation. - Uncertainty and the consequences of under- or overprediction. ### Part 2 — Scale to 100 data centers How would you share information and operate forecasting across the fleet while preserving differences between sites? #### What This Part Should Cover - Local versus shared models, site features, and model-management costs. - Evaluation at individual-site and fleet levels. ### Part 3 — Handle a new data center How would you forecast demand before a new site has enough observations to learn its own pattern? #### What This Part Should Cover - Comparable sites, planned workload assignments, and uncertainty. - Updating the forecast as local observations arrive. ### What a Strong Answer Covers - A forecasting target connected to a concrete capacity-planning decision. - A scalable modeling and data pipeline with honest treatment of missing history. - Protection against leakage and misleading aggregate accuracy. ### Follow-up Questions - How could a capacity limit make observed storage growth understate actual demand? - How would you check whether fleet-level forecasts and site-level forecasts are consistent?

Overview: Forecast daily storage demand for one data center, scale models to 100 sites, and handle new-site cold starts with shared information and uncertainty.

Read the full Apple Machine Learning Engineer interview experience this question came from

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Aug 24, 2026
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Design a forecasting approach for daily data-center storage demand. Explain how you would begin with one data center, extend the approach to 100 data centers, and produce forecasts for a newly established data center with little or no history.

Part 1 — Forecast one data center

Define the target and forecasting horizon, then describe the data, baseline, model, and evaluation method.

What This Part Should Cover Guidance

  • The distinction between new storage demand, net growth, and occupied capacity.
  • Seasonality, known future information, and chronological evaluation.
  • Uncertainty and the consequences of under- or overprediction.

Part 2 — Scale to 100 data centers

How would you share information and operate forecasting across the fleet while preserving differences between sites?

What This Part Should Cover Guidance

  • Local versus shared models, site features, and model-management costs.
  • Evaluation at individual-site and fleet levels.

Part 3 — Handle a new data center

How would you forecast demand before a new site has enough observations to learn its own pattern?

What This Part Should Cover Guidance

  • Comparable sites, planned workload assignments, and uncertainty.
  • Updating the forecast as local observations arrive.

What a Strong Answer Covers Guidance

  • A forecasting target connected to a concrete capacity-planning decision.
  • A scalable modeling and data pipeline with honest treatment of missing history.
  • Protection against leakage and misleading aggregate accuracy.

Follow-up Questions Guidance

  • How could a capacity limit make observed storage growth understate actual demand?
  • How would you check whether fleet-level forecasts and site-level forecasts are consistent?

Submit Your Answer to Earn 20XP

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