Cloud Migration Strategy: The 6 Rs Framework and How to Choose the Right One

The 6 Rs of Cloud Migration

AWS, Gartner and most cloud consultants use the "6 Rs" framework to categorise migration approaches. Each has distinct cost, risk, and time-to-value characteristics.

1. Rehost (Lift-and-Shift)

Move applications to cloud with minimal changes — typically using tools like AWS Application Migration Service or Azure Migrate. Fastest approach, lowest short-term risk. Applications run in cloud but don't benefit from cloud-native features.

• Speed: Days to weeks
• Cost saving: 20-30% infrastructure cost reduction
• Risk: Low
• Best for: Legacy applications with tight migration timelines, applications nearing end-of-life

2. Replatform (Lift, Tinker, and Shift)

Move to cloud with modest optimisations — swap database to managed RDS, move file storage to S3, containerise application. No code changes but architecture improvements.

• Speed: Weeks to months
• Cost saving: 35-50% vs on-premises
• Risk: Low-Medium
• Best for: Applications that can benefit from managed services without full refactoring

3. Refactor / Re-architect

Redesign the application to be cloud-native — microservices, serverless, containers, event-driven architecture. Highest investment, highest long-term return.

• Speed: Months to years
• Cost saving: 50-70% vs on-premises (long term)
• Risk: High during transition
• Best for: Core business applications with high growth or scalability requirements

4. Repurchase

Move to SaaS — replace self-hosted CRM with Salesforce, replace Exchange with Microsoft 365, replace on-premises ERP with cloud SaaS. Eliminates infrastructure management entirely.

5. Retire

Decommission applications that are no longer needed. Typically 10-20% of on-premises portfolio. Pure cost reduction with no replacement.

6. Retain

Keep on-premises temporarily (regulatory, latency, technical debt that's too expensive to address now). Plan for future migration once blockers are resolved.

Migration Portfolio Approach

Most enterprises use all 6 Rs simultaneously across their portfolio. A typical 200-application migration:

Start with Retire and Rehost to generate quick wins and learnings. Use the momentum and savings to fund the more complex Replatform and Refactor workloads.