Cassandra compaction backlog from tombstones
Your Cassandra cluster (write-heavy time-series telemetry) starts showing rising write latency and growing dropped-mutation counts at 04:00. Per-node metrics show pending compactions climbing into the thousands, SSTable counts per read exploding, disk IO at 100%, and tombstone warnings in the logs. A retention change last week switched a high-volume table from TTL-based expiry to periodic DELETE batches. How do you triage and stabilize this, and what's the durable fix?
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.
0:00 of about 40 min
Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.
Run or narrate your approach, then ask the coach.