When considering cloud migration strategies, organizations often evaluate three primary approaches: Rehosting, Replatforming, and Refactoring. Each method offers distinct advantages and challenges, depending on business objectives, technical requirements, and resource availability.
1. Rehosting (Lift-and-Shift)
Definition: Rehosting involves moving applications to the cloud with minimal or no changes. It’s akin to “lifting” applications from the current environment and “shifting” them to the cloud.
Use Cases:
- Rapid migration needs.
- Limited cloud expertise.
- Short-term cost savings.
Advantages:
- Quick deployment.
- Minimal upfront costs.
- Reduced risk due to unchanged application architecture.
Disadvantages:
- Doesn’t leverage cloud-native features.
- Potential for higher operational costs over time.
- May carry over existing application inefficiencies.
Example: Migrating a virtual machine hosting a legacy application to a cloud-based virtual machine without modifying the application.
2. Replatforming (Lift-Tinker-and-Shift)
Definition: Replatforming entails making minimal changes to applications to optimize their performance in the cloud environment without altering their core architecture.
Use Cases:
- Desire to benefit from cloud efficiencies without full-scale redevelopment.
- Need for improved scalability and performance.
Advantages:
- Balances speed and optimization.
- Enables use of cloud-native services like managed databases.
- Improved application performance and scalability.
Disadvantages:
- Requires more effort than rehosting.
- Potential for scope creep if not carefully managed.
Example: Migrating an application to the cloud and replacing its traditional database with a cloud-managed database service.
3. Refactoring (Re-architecting)
Definition: Refactoring involves reimagining and rewriting applications to fully exploit cloud-native features, often resulting in significant changes to the application’s architecture and codebase.
Use Cases:
- Need for high scalability and resilience.
- Desire to adopt microservices or serverless architectures.
- Long-term strategic cloud adoption.
Advantages:
- Maximizes benefits of cloud-native features.
- Enhanced scalability, performance, and resilience.
- Potential for significant cost savings over time.
Disadvantages:
- Most time-consuming and resource-intensive approach.
- Requires significant development effort and expertise.
Example: Breaking down a monolithic application into microservices and deploying them using containers orchestrated by Kubernetes.
Comparison Summary
| Aspect | Rehosting | Replatforming | Refactoring |
|---|---|---|---|
| Complexity | Low | Medium | High |
| Time to Implement | Short | Moderate | Long |
| Cost | Low initial, higher ongoing | Moderate | High initial, lower ongoing |
| Cloud Optimization | Minimal | Moderate | Extensive |
| Risk | Low | Moderate | High |
Choosing the Right Strategy
- Rehosting is suitable for organizations seeking quick cloud adoption with minimal changes.
- Replatforming is ideal for those wanting to optimize applications for the cloud without extensive redevelopment.
- Refactoring is best for businesses aiming to fully leverage cloud-native capabilities for long-term benefits.
The choice among these strategies should align with the organization’s goals, resources, and desired outcomes.