My first instinct was to start designing classes and I went down that path for maybe two minutes before they redirected me.
Start by clarifying requirements (scale, consistency, recovery objectives) and then propose a modular design that separates backup creation, synchronization, and failure handling. Emphasize trade-offs between full/incremental backups, push/pull models, and consistency mechanisms, and discuss how to scale horizontally and handle failures with retries, checksums, and monitoring.
Pro tip: Demonstrate Netflix-scale thinking by discussing how to handle massive data volumes and global distribution, and tie your design to Netflix's specific needs like high availability and disaster recovery.
Ask about scale (data size, file count, rate of change), consistency needs (point-in-time vs eventual), recovery objectives (RTO/RPO), and environment (on-prem, cloud, multi-region). This shows you avoid assumptions and design for the actual problem.
Outline components: a backup service that scans source, a metadata store, a transfer mechanism, and a destination store. Decide on push vs pull, full vs incremental, and how to mirror the directory structure (e.g., using a manifest or filesystem snapshots).
Discuss techniques like checksums, versioning, and atomic operations to ensure consistency. Explain how to handle file deletions, renames, and conflicts, and how to verify integrity after transfer.
Address horizontal scaling: sharding by directory or file, parallel transfers, distributed workers, and load balancing. Consider using a distributed queue and object storage for scalability.
Describe retry mechanisms, idempotency, checkpointing, and monitoring. Discuss how to handle partial failures, network issues, and how to recover from a failed backup without starting over.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.