System designMediumsd-g609

Subject Cold storage logs metricsLevel Mid–Senior~40 minCommon in Storage & CDN interviewsIndustries Technology

Question

Design a log/metrics cold-storage system for an observability platform. Constraints: ingest is tens of millions of events/sec at peak, recent data (hours) must be queryable fast, older data (months/years) is queried rarely and must be cheap, retention is years for compliance, and queries are mostly time-range + filter + aggregate. Cover ingest, the hot-to-cold path, and the query model.

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.