System designMediumsd-g259

Subject File storageLevel Mid–Senior~40 minCommon in Databases & SQL · Storage & CDN interviewsIndustries Technology, Software development

Question

Design the object-storage API and metadata layer for an S3-compatible service used heavily for media: multipart uploads of multi-GB objects, strong read-after-write so a client that uploads then immediately reads gets the new bytes, range reads for video seeking, and integrity guarantees (a corrupted byte must be detectable). Design the API surface, how multipart upload finalizes consistently, and how reads see a coherent view under concurrent overwrites.

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.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.