What caused the sudden increase in latency for MinIO's erasure coding operations during peak usage hours yesterday?

Introduction

The sudden increase in latency for MinIO's erasure coding operations during peak usage hours yesterday is a critical issue that demands immediate attention. This analysis will systematically identify, validate, and address the root cause while considering both short-term fixes and long-term implications for our product strategy.

I'll approach this problem by first clarifying the context, then ruling out external factors before diving deep into our product ecosystem, user journey, and relevant metrics. We'll generate data-driven hypotheses, conduct root cause analysis, and develop a comprehensive plan for validation and resolution.

Step 1

Clarifying Questions (3 minutes)

• Looking at the timing, I'm thinking this might be related to a recent deployment. Have there been any system changes or updates in the past 48 hours?

Why it matters: Recent changes often correlate with performance issues. Expected answer: Yes, a minor update was deployed yesterday morning. Impact on approach: If true, we'd focus on the changes made in that update.

• Considering the specificity to peak hours, I'm wondering about usage patterns. Can you provide more details on what "peak usage hours" means for our system?

Why it matters: Understanding usage patterns helps identify potential capacity issues. Expected answer: Peak hours are typically 2-5 PM EST on weekdays. Impact on approach: This would guide our investigation into potential resource constraints.

• Given the focus on erasure coding, I'm curious about data characteristics. Has there been any significant change in the type or size of data being processed?

Why it matters: Changes in data patterns can affect erasure coding performance. Expected answer: No significant changes reported in data characteristics. Impact on approach: If true, we'd look more closely at system-level issues rather than data-related ones.

• Thinking about system health, I'm interested in error rates. Have we seen any increase in error rates or unusual log entries coinciding with the latency spike?

Why it matters: Errors often precede or accompany performance issues. Expected answer: Some increase in timeout errors noted during peak hours. Impact on approach: This would direct us to investigate potential bottlenecks or resource exhaustion.