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Dropbox System Design
Visual Problem Diagram
Scenario
A user uploads a 10 GB video on hotel Wi-Fi—the upload must resume after disconnect while another device still shows "syncing" with the wrong version until metadata catches up. Chunked storage, revision sync, and conflict copies define Dropbox-class design.
Design a cloud file sync product where files are split into chunks, stored in object storage, and synchronized across devices with a clear metadata model. Users blame data loss and silent conflicts—your design must address resume, revision, and conflict UX.
You should support folder tree, upload/download, delta sync, sharing, and conflicts. Be ready to explain content-defined chunking and revision-based sync.
Constraints
Folders/files, chunked upload, sync, share links, conflict copies, delete/trash
99.999999999% durability (11 nines) goal for blobs, resume uploads, sync seconds-level, ACL enforced
700M users, exabytes storage, billions files, viral share links
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