Companies migrate mainframes to Azure or AWS using strategies like rehosting (lift-and-shift with emulation), replatforming (to managed services), and refactoring (to microservices with AI-assisted code conversion), often partnering with specialists to handle COBOL/PL/I code, batch jobs, and data replication while minimizing downtime.
Key Migration Strategies
Enterprises follow the “6 Rs” framework, prioritizing low-risk apps first.
- Rehost: Emulate mainframe environments on IaaS (e.g., Azure VMs or AWS EC2) with minimal code changes using tools like TmaxSoft OpenFrame or AWS Mainframe Modernization; ideal for quick hardware retirement.
- Replatform: Shift to PaaS like Azure App Service or AWS Lambda, swapping databases (e.g., DB2 to Azure SQL) and optimizing batch processes; balances speed and cloud benefits.
- Refactor/Rebuild: Convert legacy code to Java/microservices with AI tools (e.g., AWS Transform or Azure code conversion), enabling CI/CD and scalability; suited for high-value systems.
Phased approaches include assessment, target setup (landing zones/IaC), iterative moves with testing, and optimization.
Azure Migration Examples
AWS Migration Examples
Challenges and Best Practices
Main challenges include code complexity, data replication, skills gaps, and downtime risks. Mitigate with automated testing/CI/CD, phased rollouts, and tools for code quality evaluation. Post-migration, focus on observability, security (IAM/Entra ID), and AI integration for ongoing value.
