Code Room
System designHardsd-g721
Subject Object storageLevel Senior–Staff~45 minCommon in Databases & SQL · Storage & CDN interviewsIndustries Technology

Question

Design the core write/read path of an S3-like object store focused on large objects: objects up to 5TB uploaded as multipart chunks over unreliable client connections, eleven-nines durability, strong read-after-write consistency for new objects, and high aggregate throughput. Ignore versioning/lifecycle — focus on how a multi-gigabyte object is durably written across the cluster and read back, and how the system stays consistent. How do you do it?

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.

Narrate your design
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Run or narrate your approach, then ask the coach.