What caused the sudden 30% increase in latency for Google Cloud storage services yesterday?

Introduction

The sudden 30% increase in latency for Google Cloud storage services yesterday is a critical issue that demands immediate attention and thorough analysis. As we delve into this problem, we'll employ a systematic approach to identify, validate, and address the root cause while considering both short-term fixes and long-term implications for our service reliability.

I'll structure our analysis by first clarifying the situation, ruling out external factors, understanding the product and user journey, breaking down the metric, gathering relevant data, forming hypotheses, conducting root cause analysis, and finally proposing validation methods and next steps.

Step 1

Clarifying Questions (3 minutes)

• What specific time period did we observe this latency increase?

• Are all regions and data centers affected equally?

• Have we seen any correlated increase in error rates or failed requests?

• Were there any recent deployments or configuration changes prior to the incident?

• Is this latency increase consistent across all types of storage operations (read, write, delete)?

• Have we received any customer complaints or support tickets related to this issue?

Why this matters: Understanding the scope and context of the latency increase is crucial for narrowing down potential causes and focusing our investigation.

Hypothetical answer: The latency spike began at 2 PM UTC yesterday, affecting all regions but with varying severity. No significant increase in error rates was observed. A minor configuration change was deployed to optimize caching 6 hours before the incident. The latency increase appears to be more pronounced for read operations.

Impact on approach: This information suggests we should focus on recent changes and read-specific operations, while also investigating potential regional differences in infrastructure or traffic patterns.