Code Room
On-callHardoc-g651
Subject Corrupted sstable durabilityLevel Senior–Staff~40 minCommon in Storage & CDN interviewsIndustries Technology

Question

A Cassandra/RocksDB-style node starts throwing read errors on a subset of keys: queries for certain partitions return `CorruptSSTableException` / checksum-mismatch errors, and the node is logging block-checksum failures during compaction. Dashboards: read error rate on one node climbed to ~2%; the other replicas serve the same keys fine; SMART data on one NVMe drive shows rising reallocated-sector and uncorrectable-error counts; the corrupted SSTable was written 6 weeks ago and only now read; replication factor is 3. No recent deploy. How do you triage a corrupted SSTable / silent durability fault and recover without losing data or propagating the corruption?

What a strong answer looks like

Stop the bleeding first (mitigate), then form hypotheses from real signals. Separate root cause from symptom, communicate status as you go, and close with what prevents a repeat.

Diagram & narrate the incident
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Run or narrate your approach, then ask the coach.