Jumped straight into storage and APIs before nailing down the requirements, which I think hurt me.
Start by clarifying requirements and constraints (scale, consistency, file sizes, sharing, offline support). Then design the high-level architecture covering storage, metadata, sync, and sharing, and dive deep into critical components like chunking, deduplication, conflict resolution, and notification. Finally, discuss trade-offs and potential bottlenecks.
Pro tip: Focus on the sync algorithm and conflict resolution early, as they are the most challenging parts and often overlooked. Also, quantify scale (e.g., number of users, files, QPS) to guide design decisions.
Ask questions to understand functional and non-functional requirements: file size limits, number of users, sync latency, offline support, sharing features, consistency vs. availability, and security.
Outline the main components: client apps, API gateway, metadata service, block storage, notification service, and sync engine. Describe data flow for upload, download, and sync.
Detail the design of metadata storage (e.g., SQL vs. NoSQL), file chunking and deduplication, versioning, conflict resolution (e.g., last-write-wins, vector clocks), and change notification (e.g., long polling, WebSockets).
Discuss how to scale each component (sharding, replication, caching), ensure durability (replication, erasure coding), and handle failures (retries, idempotency).
Articulate trade-offs (e.g., consistency vs. latency, storage cost vs. deduplication overhead) and potential optimizations (e.g., delta sync, compression, CDN for downloads).
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.