Cloud File Storage (Dropbox)
Sync files across devices efficiently with deduplication and versioning.
Hard50 minChunkingSyncConflict resolution
A cloud file storage service like Dropbox or Google Drive keeps a user's files in sync across all their devices and lets them share folders. The key ideas are splitting files into chunks so only changed parts move, separating metadata from content, and reconciling edits made on different devices.
Clarify requirements
Functional
- Upload, download, delete files; folders.
- Automatic sync across a user's devices (desktop client watches a folder).
- Version history (restore older versions for 30 days).
- Share files/folders with other users (view/edit).
- Out of scope: real-time co-editing of documents, full-text search (extensions).
Non-functional
- 100M DAU, 500M total users; files up to 50 GB.
- Sync latency: changes visible on other devices within seconds.
- Strong durability (no data loss) and consistency of metadata (no corrupted folder trees).
- Efficient bandwidth on slow networks; resumable uploads.
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