Code Room
System designHard
Question
Design a content-addressable storage system (CAS) that backs a container-image registry and an artifact/package store. Constraints: blobs keyed by their cryptographic digest, heavy sharing of base layers across images, immutable blobs but mutable tags pointing at them, billions of small-to-medium blobs, and aggressive caching is safe because content can't change under a digest. Cover the addressing model, the tag/manifest layer, and GC.
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.
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