Design a File Storage Service
Last updated: January 29, 2026
Quick Overview
Design a high-throughput file storage system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
OpenAI
January 29, 20261
4
4,923 solved
Design a high-throughput file storage system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
System design interviews at OpenAI typically last 45-60 minutes. You are expected to drive the conversation, starting from requirements gathering through to a detailed architecture. The interviewer will evaluate your ability to handle ambiguity and make practical engineering decisions.
What the Interviewer Expects
- Clearly define functional and non-functional requirements
- Propose a reasonable high-level architecture with core components
- Choose appropriate data storage solutions with basic justification
- Discuss basic scaling strategies (horizontal scaling, caching)
- Identify potential bottlenecks and suggest simple solutions
Key Topics to Cover
How to Approach This
- Start by clarifying functional and non-functional requirements with the interviewer.
- Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
- Draw a high-level architecture first, then deep dive into 1-2 critical components.
- Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
- Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
- How would you implement rate limiting to protect the system?
- How would you handle a region-wide outage?
- What happens if one of your database nodes goes down?
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Requirements
Functional Requirements:
- Upload and Download Files: Users should be able to upload and download files of various types and sizes (up to 5GB).
- File Metadata: The system should store m...
Capacity Estimation
To estimate capacity, consider the following assumptions:
- Daily Active Users: 1 million users.
- Average Upload Size: 100 MB per file.
- Average Downloads per User per Day: 5 downloads o...
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