Veteran engineer asking this one meant I couldn't get away with surface-level stuff.
Start by clarifying functional and non-functional requirements, then outline a high-level architecture covering storage, metadata, synchronization, and sharing. Dive into data modeling for files and permissions, and discuss trade-offs in consistency, scalability, and cost.
Pro tip: Emphasize how you would handle large file uploads with chunking and resumability, and discuss the importance of idempotency in sync operations to avoid data corruption.
Ask questions to understand scope: user scale, file size limits, sharing features, sync needs, and consistency requirements. Define core entities like users, files, folders, and permissions.
Sketch the main components: client apps, API gateway, metadata service, block storage, and synchronization service. Explain how they interact for uploads, downloads, and sharing.
Design schemas for metadata (files, folders, versions, permissions) and choose storage solutions (e.g., object storage for blobs, relational DB for metadata). Discuss indexing for efficient queries.
Detail how to handle file sync across devices, including conflict resolution, change notifications, and delta sync. Discuss consistency models (strong vs. eventual) and their trade-offs.
Address scaling challenges: partitioning metadata, caching, CDN for downloads, and handling hot files. Discuss trade-offs between consistency, availability, latency, and cost.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.