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File Storage System Design
Visual Problem Diagram
Scenario
A design team syncs 50 GB folders while three users edit the same file offline—merge conflicts and partial upload resumes separate Dropbox from dumb S3. The interview covers metadata, chunking, sync protocol, and conflict resolution.
Design a cloud file storage service like Dropbox where users upload files, sync across devices, and share folders. The core is metadata service + chunked object storage plus an efficient sync protocol.
You should support upload/download, folder hierarchy, sync, sharing, and conflict handling. Be ready to explain chunking, deduplication, and revision-based sync.
Constraints
Upload/download files, folder hierarchy, multi-device sync, share links, conflict handling
99.9% durability, resume interrupted uploads, sync detect changes in seconds, ACL enforced
500M users, exabytes storage, billions files, heavy read on popular shared links
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