Migrating Legacy Platform Without Downtime
How we modernized a 15-year-old core platform to cloud-native architecture with zero business disruption
The Challenge
A regional insurance carrier’s core policy administration system was a 15-year-old monolithic application running on-premise. The legacy COBOL-based system processed 500,000+ policies but suffered from frequent outages, 72-hour deployment cycles, inability to integrate with modern InsurTech partners, and maintenance by a shrinking pool of specialized developers. Any extended downtime would halt policy issuance and claims processing, potentially violating regulatory SLAs. The carrier needed modernization without disrupting daily operations serving 200,000+ policyholders.
Key Pain Points
- Frequent outages impacting policy and claims processing
- 72-hour deployment cycles preventing rapid feature delivery
- Inability to integrate with modern InsurTech partners
- Shrinking talent pool for legacy system maintenance
Our Solution
We executed a strangler fig migration strategy, incrementally replacing legacy functionality with cloud-native microservices while maintaining the original system as the source of truth during transition. API facades provided unified access across old and new components. We built automated data synchronization to keep both systems consistent, with comprehensive reconciliation checks. New services were deployed on Kubernetes with CI/CD pipelines enabling multiple daily deployments. Critical business logic was extracted through a combination of code analysis, stakeholder interviews, and extensive testing. The migration proceeded module by module over 14 months with zero planned downtime.
Implementation Approach
- Discovery & Assessment: Reverse-engineered legacy system, documented business rules, and designed migration roadmap
- Architecture & Foundation: Built cloud infrastructure, API facades, and data synchronization framework
- Incremental Migration: Migrated modules sequentially using strangler pattern with comprehensive testing
- Optimization & Cutover: Decommissioned legacy components, optimized performance, and trained operations team
Technologies Used
Cloud Migration, Kubernetes, Microservices, API Gateway, CI/CD Pipeline
Results
| Metric | Before | After | Improvement |
|---|---|---|---|
| Deployment Time | 72 hours | 30 minutes | 95% faster |
| System Uptime | 97.5% | 99.9% | +2.4% |
| Infrastructure Cost | $180K/month | $72K/month | 60% reduction |
| Integration Time | 6-12 months | 2-4 weeks | 90% faster |
“The zero-downtime migration seemed impossible when we started. The AmasaTech team’s strangler pattern approach let us modernize piece by piece while keeping the business running. We’re now deploying features in hours instead of months.”
— Robert Stevens, Chief Technology Officer, Regional Insurance Carrier
Key Takeaways
- Strangler fig pattern enables safe incremental modernization
- API facades provide migration flexibility without breaking consumers
- Comprehensive data synchronization is critical during dual-run periods
- Cloud-native architecture dramatically improves operational agility
Related Resources
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