Q: You need to migrate a 500GB production RDS database to a new region with minimal downtime. How?
1. Create a cross-region read replica — in RDS, create a read replica in the target region. It will replicate all data and stay in sync v...
#AWS #RDS & Databases #L2 #Cloud #Infrastructure
🎙️ Candidate Opening & Architectural Context
""AWS reliability requires differentiating between AWS control plane limits and host-level resource exhaustion. When addressing this question, I walk the interviewer through our production incident runbook: isolating the blast radius, checking diagnostic logs and metrics, and applying a safe fix.""
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🛠️ Production Runbook & Step-by-Step Resolution
1️⃣
Initial Diagnostics & Root Cause Analysis
Total downtime: a few minutes during promotion + connection string update.
- Create a cross-region read replica — in RDS, create a read replica in the target region. It will replicate all data and stay in sync via binlog replication (MySQL) or streaming replication (Postgres).
- Wait for the replica to catch up — replication lag should approach 0.
- Maintenance window — stop writes to the source DB (or put app in maintenance mode).
- Promote the replica — in the target region, promote the read replica to a standalone primary. This takes seconds.
2️⃣
Remediation & Permanent Safeguards
- Update app config — point the connection string to the new region's DB endpoint.
- Verify — test the app against the new DB.
- Cleanup — once confirmed, decommission the source DB.
💡 The Senior SRE Gold Nugget (Key Architectural Takeaway)
"Pro-Tip: Create a cross-region read replica — in RDS, create a read replica in the target region. It will replicate all data and stay in sy."
⚡ 60-Second Elevator Pitch Talking Points
- Create a cross-region read replica — in RDS, create a read replica in the target region. It will ...
- Wait for the replica to catch up — replication lag should approach 0.
- Maintenance window — stop writes to the source DB (or put app in maintenance mode).
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