Design a large-scale File Storage Platform
Last updated: July 17, 2025
Quick Overview
Design a low-latency file storage system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Dropbox
System Design
Software Engineer
Dropbox
July 17, 2025Software Engineer
Onsite
System Design
Medium
3
14
4,355 solved
Design a low-latency file storage system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
System design interviews at Dropbox 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
- Systematically gather requirements and estimate capacity (QPS, storage, bandwidth)
- Design a scalable architecture with clear component responsibilities
- Make well-reasoned database and caching decisions with trade-off analysis
- Address consistency vs availability trade-offs specific to the use case
- Discuss partitioning strategy, replication, and data modeling
- Cover failure handling, monitoring, and alerting strategies
Key Topics to Cover
Partitioning and sharding strategies
API design and rate limiting
High-level architecture and component design
Security and authentication
Failure handling and fault tolerance
Message queues and async processing
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 do you ensure data consistency across multiple services?
- 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:
- File Upload/Download: Users can upload and download files of various sizes (>1TB).
- File Sharing: Users can share files with other users or generate public li...
Capacity Estimation
Back-of-Envelope Calculations:
- User Base: Assume we have 10 million users.
- Average File Size: Assume an average file size of 5MB.
- Daily Active Users: Assume 10% daily active u...
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