Zero-Downtime Cloud Migration to Multi-Region AWS
Executed a live database and microservice migration from bare-metal servers to Amazon EKS and Aurora PostgreSQL with zero service interruption for 500,000+ active users.
Zero DowntimeMulti-Region Failover45% Cost Reduction
Key Takeaways
- Phased cutover via Route 53 weighted DNS routing and continuous AWS DMS database replication achieved zero dropped user sessions.
- Migrating from physical data center leases to Amazon EKS autoscaling reduced monthly infrastructure spend from $180K to $99K.
- Multi-region active-passive failover dropped Mean Time to Recovery (MTTR) from 4+ hours to under 15 minutes.
The Challenge
A high-growth B2B SaaS platform serving 500,000 active users operated on aging bare-metal servers in a single co-located facility. A single hardware failure in 2022 caused a 6-hour blackout resulting in $2.1M in SLA penalty credits. The company required full cloud migration with zero maintenance downtime and multi-region resilience.
Architecture & Technical Approach
- Phase 1 (Containerization): 14 core services containerized into Docker images and validated with production traffic shadow mirroring via GoReplay.
- Phase 2 (Continuous Database Sync): PostgreSQL migrated to Amazon Aurora Multi-Region using AWS DMS with ongoing Change Data Capture (CDC) replication.
- Phase 3 (Canary Cutover): Shifted production traffic in increments (5% -> 25% -> 75% -> 100%) using Amazon Route 53 weighted routing and automated health check validation.
Quantitative Benchmarks & Results
| Metric | On-Premises Co-Location | AWS Multi-Region EKS | Delta |
|---|---|---|---|
| Monthly Infrastructure Cost | $180,000 | $99,000 | -$81,000 (-45.0%) |
| Migration Service Downtime | Expected: 2 Hours | Actual: 0.0 Seconds | Zero Downtime Achieved |
| Regional Disaster Recovery MTTR | 4+ Hours | < 15 Minutes | 16x Faster Recovery |
| Deployment Cadence | Weekly Maintenance Windows | Multiple Daily Deploys | 10x Velocity |
Production Reliability & Lessons Learned
Running automated checksum audits every 5 minutes across the on-premise database and Aurora replica ensured absolute data parity before initiating final traffic cutover.