Interview Questions/Troubleshooting Scenarios/HTTP 503 Errors During DB Maintenance
BeginnerScenario
5 min

HTTP 503 Errors During DB Maintenance

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Interview Question

Users face 503 errors during scheduled DB maintenance. How do you minimize impact and handle gracefully?

Key Points to Cover
  • Announce and schedule during low-traffic windows
  • Failover to replicas or use read-only mode
  • Use connection draining and retries in app
  • Show user-friendly error or maintenance page
  • Add automation to shorten maintenance window
Evaluation Rubric
Plans maintenance with low impact30% weight
Mentions replicas or failover30% weight
Provides graceful user handling20% weight
Automates/reduces downtime20% weight
Hints
  • 💡Maintenance windows should have rollback plans.
Common Pitfalls to Avoid
  • ⚠️Performing maintenance during peak hours without prior notice.
  • ⚠️Not having a clear communication plan for users.
  • ⚠️Assuming read replicas are always sufficient without verifying read/write traffic patterns.
  • ⚠️Implementing aggressive retries without backoff, leading to system overload.
  • ⚠️Lack of a tested rollback plan, causing extended downtime when issues arise.
Potential Follow-up Questions
  • How to make DB upgrades zero-downtime?
  • What about schema migrations?
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