Disk saturation from debug logging
A single-host analytics ingestion service (Java) suddenly slows to a crawl at 03:00. Throughput drops 80%, GC logs show frequent long pauses, and `free -m` shows almost no free memory and a large amount in 'buff/cache'. `iostat` shows the data disk at 100% util with high `await`. CPU is mostly in `iowait` and `%sy`. No deploy happened, but a config change yesterday set DEBUG-level logging on a hot path, and log files have grown to hundreds of GB. The host also runs the embedded storage engine on the same disk. Triage and mitigate.
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 30 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.