Code Room
On-callHardoc-g586
Subject Object storage 429 throttleLevel Senior–Staff~35 minCommon in Storage & CDN interviewsIndustries Technology

Question

Your ingestion pipeline that writes to an S3-compatible object store starts getting a flood of HTTP 429 SlowDown responses during a traffic burst; the dashboard shows request error rate spiking and the per-prefix request graph shows nearly all writes hitting object keys that share the prefix `events/2026/06/24/`. The pipeline retries aggressively with no backoff, which makes the 429s worse. A new high-volume customer onboarded this morning and the pipeline auto-shards by date, not by entity. How do you triage and stop the throttling, then fix the key design durably?

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.