System designHardsd-g710

Subject Block storageLevel Senior–Staff~45 minCommon in Databases & SQL · Storage & CDN · Distributed systems interviewsIndustries Technology

Question

Design an EBS-like distributed block-storage service that presents network-attached virtual disk volumes to VMs. Each volume must look like a local block device, survive single-disk and single-host failures with 99.999% durability, deliver low-tail-latency 4KB random I/O, and support snapshots. A volume attaches to exactly one VM at a time. How do you lay out data, replicate it, and handle a host failure without corrupting the volume?

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.