What factors are contributing to the increased latency in Rackspace's OpenStack Public Cloud instances over the last two weeks?

Introduction

Increased latency in Rackspace's OpenStack Public Cloud instances over the past two weeks 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 cloud infrastructure.

I'll approach this problem by first clarifying the context, then ruling out external factors before diving deep into our product ecosystem, metrics, and potential internal causes. We'll generate data-driven hypotheses, conduct root cause analysis, and develop a comprehensive plan to resolve the issue and prevent future occurrences.

Step 1

Clarifying Questions (3 minute)

• Looking at the timing, I'm thinking there might be a recent change in our infrastructure. Have there been any significant updates or deployments to our OpenStack environment in the last month?

Why it matters: Recent changes often correlate with performance issues. Expected answer: Yes, there was a major update two weeks ago. Impact on approach: If confirmed, we'd focus on the update's components and rollout process.

• Considering user impact, I'm curious about the scope. Is this latency increase affecting all instances or specific types/regions?

Why it matters: Helps narrow down potential causes and affected components. Expected answer: The issue is more pronounced in certain regions. Impact on approach: We'd investigate region-specific factors and infrastructure differences.

• Given the nature of cloud services, I'm wondering about resource utilization. Have we seen any unusual spikes in CPU, memory, or network usage across our infrastructure?

Why it matters: Resource constraints often lead to latency issues. Expected answer: There's been a gradual increase in overall resource utilization. Impact on approach: We'd focus on capacity planning and resource optimization strategies.

• Thinking about external factors, has there been any change in our monitoring or measurement systems that could affect how we're calculating latency?

Why it matters: Ensures we're dealing with a real issue, not a measurement anomaly. Expected answer: No changes to monitoring systems have been made. Impact on approach: We'd rule out measurement errors and focus on actual performance issues.