7Rs Cloud Migration Strategies: A Comprehensive Guide

28 Jan 2025 - Shyam Mohan

When most cloud engineers think of migration, the term “Lift and Shift” often dominates the discussion. But while this approach works in specific scenarios, it’s far from a one-size-fits-all solution. Organizations moving to the cloud need to evaluate multiple strategies based on their business needs, technical challenges, and long-term goals. This is where the 7Rs Cloud Migration Strategies come into play.

Understanding the 7Rs of Cloud Migration

The 7Rs framework provides a structured approach for migrating applications, workloads, and infrastructure to the cloud. Let’s dive deep into each strategy to understand when and how to use them effectively.

1️⃣ Rehost (Lift and Shift)

Rehosting, also known as “lift and shift,” is a cloud migration strategy where you move an application and its associated data from one environment to another, typically from an on-premises data center to a cloud environment, without redesigning the application. It’s like picking up your application and moving it to a new house without changing its furniture or layout.

Here’s a breakdown of the key aspects of rehosting:

How it works:

• Copy the application: You create an exact copy of your application, including its code, configurations, and dependencies.
• Move to the cloud: You deploy this copy to a cloud environment, often using virtual machines or containers that mimic your existing infrastructure.
• Minimal changes: You make little to no changes to the application’s architecture or code.

Benefits of rehosting:

• Speed: Rehosting is often the fastest way to migrate to the cloud since it requires minimal changes.
• Cost-effective (initially): It can have lower upfront costs compared to other migration strategies as it avoids extensive development work.
• Reduced risk: Since you’re not changing the application significantly, there’s less risk of introducing new bugs or issues.

Drawbacks of rehosting:

• Doesn’t optimize cloud benefits: You might not fully utilize the cloud’s scalability, elasticity, and cost-optimization features.
• Potential performance issues: Applications designed for on-premises environments might not perform optimally in the cloud without adjustments.
• Technical debt: You might carry over existing technical debt and limitations to the cloud.

Use cases for rehosting:

• Legacy applications: When you have applications that are difficult or costly to re-architect.
• Time-sensitive migrations: When you need to move to the cloud quickly.
• Initial cloud adoption: As a first step to gain experience with cloud environments.

Alternatives to rehosting:

• Replatforming: Making some modifications to the application to better leverage cloud services.
• Refactoring/Re-architecting: Redesigning the application to be cloud-native and fully utilize cloud capabilities.
• Repurchasing: Replacing the application with a cloud-based SaaS solution.

Important considerations:

• Application dependencies: Ensure all dependencies are compatible with the cloud environment.
• Performance testing: Thoroughly test the application in the cloud to identify any performance bottlenecks.
• Security: Implement appropriate security measures to protect your application and data in the cloud.

2️⃣ Replatform (Lift, Tinker, and Shift)

Replatforming, often referred to as “lift, tinker, and shift,” is a cloud migration strategy that involves making some modifications to an application to take advantage of cloud capabilities while minimizing code changes. It’s a middle ground between rehosting (lift and shift) and refactoring (re-architecting).

Here’s a breakdown of the key aspects of replatforming:

How it works:

• Lift: You move your application to the cloud, similar to rehosting.
• Tinker: You make targeted changes to the application to leverage cloud services and features. This might involve:
  • Migrating to managed services (e.g., databases, message queues)
  • Containerizing the application
  • Optimizing configurations for the cloud environment
• Shift: You deploy the modified application in the cloud.

Benefits of replatforming:

• Faster than refactoring: It requires less development effort compared to re-architecting, resulting in quicker migration.
• Cost-effective: It can reduce operational costs by leveraging managed services and optimizing resource utilization.
• Improved performance: Applications can benefit from cloud-native features like scalability and elasticity.
• Reduced risk: It involves less code changes compared to refactoring, minimizing the risk of introducing new issues.

Drawbacks of replatforming:

• Limited optimization: It might not fully utilize all the cloud’s capabilities compared to a fully re-architected application.
• Potential compatibility issues: Some modifications might be necessary to ensure compatibility with cloud services.
• Requires some development effort: It involves more changes than rehosting, requiring some development resources.

Use cases for replatforming:

• Applications with a solid architecture: When the application’s core design is sound but can benefit from cloud optimizations.
• Modernizing legacy applications: When you want to update older applications without a complete rewrite.
• Migrating to managed services: When you want to offload operational tasks to cloud providers.

Alternatives to replatforming:

• Rehosting: For quick migrations with minimal changes.
• Refactoring: For fully leveraging cloud capabilities and achieving maximum scalability and performance.
• Repurchasing: Replacing the application with a cloud-based SaaS solution.

Important considerations:

• Application dependencies: Ensure all dependencies are compatible with the cloud environment and the chosen cloud services.
• Testing: Thoroughly test the application after making changes to ensure it functions correctly in the cloud.
• Security: Implement appropriate security measures to protect your application and data in the cloud.

3️⃣ Repurchase (Drop and Shop)

In this approach, an existing application is replaced with a SaaS-based solution.

✅ When to Use: Repurchasing, often referred to as “drop and shop,” is a cloud migration strategy where you replace your existing on-premises application with a cloud-based Software-as-a-Service (SaaS) solution. It’s like dropping your old car and shopping for a brand new one. Instead of moving your existing application to the cloud (like in rehosting or replatforming), you essentially start fresh with a pre-built, cloud-native application.

Here’s a detailed look at repurchasing:

How it Works:

1. Identify a SaaS Solution: You evaluate available SaaS applications that meet your business needs and functional requirements. This often involves researching vendors, comparing features, and potentially conducting trials.
2. Migrate Data: You migrate your data from your existing application to the new SaaS platform. This might involve data transformation, cleaning, and mapping to fit the SaaS application’s data model.
3. Integrate (if necessary): You might need to integrate the new SaaS application with other existing systems within your organization. This could involve APIs, webhooks, or other integration methods.
4. Train Users: You train your users on how to use the new SaaS application. This is crucial for successful adoption and realizing the benefits of the new system.
5. Decommission the Old System: Once the new SaaS application is up and running and users are trained, you decommission your old on-premises application.

Benefits of Repurchasing:

• Reduced Costs: You can often reduce IT infrastructure and maintenance costs by moving to a SaaS model. You no longer need to manage servers, operating systems, or application updates.
• Faster Deployment: SaaS solutions are typically deployed quickly, allowing you to get up and running faster than with other migration strategies.
• Access to Latest Features: You automatically gain access to the latest features and updates provided by the SaaS vendor, without having to manage upgrades yourself.
• Scalability and Elasticity: SaaS solutions often offer built-in scalability and elasticity, allowing you to easily adjust resources as needed.
• Focus on Core Business: By offloading IT management to the SaaS vendor, your team can focus on core business activities.

Drawbacks of Repurchasing:

• Potential Feature Gaps: The SaaS solution might not perfectly match all the features of your existing application. You might have to adapt your processes or accept some feature gaps.
• Vendor Lock-in: You become dependent on the SaaS vendor and their platform. Switching vendors can be complex and costly.
• Data Security and Compliance: You need to carefully evaluate the security and compliance practices of the SaaS vendor to ensure your data is protected.
• Customization Limitations: SaaS solutions typically offer limited customization options compared to on-premises applications.
• Integration Challenges: Integrating the SaaS application with existing systems can sometimes be challenging.

Use Cases for Repurchasing:

• Commodity Applications: For applications that are not core differentiators for your business, such as CRM, HR, or email.
• Legacy Applications with Limited Support: When your existing application is old and difficult to maintain.
• When Speed is Critical: When you need to migrate to the cloud quickly.

Alternatives to Repurchasing:

• Rehosting (Lift and Shift): For quickly moving an application to the cloud without changes.
• Replatforming (Lift, Tinker, and Shift): For making some modifications to the application to leverage cloud services.
• Refactoring/Re-architecting: For redesigning the application to be cloud-native.

Important Considerations:

• Requirements Gathering: Thoroughly document your requirements before evaluating SaaS solutions.
• Vendor Evaluation: Carefully evaluate potential SaaS vendors, considering factors like features, pricing, security, and support.
• Data Migration Planning: Develop a detailed plan for migrating your data to the new SaaS platform.
• Change Management: Prepare your users for the change and provide adequate training.

💡 Example: Switching from a self-hosted email system to Microsoft 365 or moving from an in-house CRM to Salesforce.

4️⃣ Refactor (Re-architect)

Refactoring, also known as re-architecting, is a cloud migration strategy that involves completely redesigning and rewriting an application to take full advantage of cloud-native services and architectures. It’s the most comprehensive and often the most complex migration strategy, but it can also yield the greatest long-term benefits.

Here’s a detailed look at refactoring:

How it works:

1. Assessment: You thoroughly analyze your existing application to understand its functionality, dependencies, and limitations.
2. Design: You design a new architecture for the application, leveraging cloud-native principles like microservices, serverless computing, and containerization. This often involves breaking down the application into smaller, independent components that can be deployed and scaled independently.
3. Development: You rewrite the application code based on the new architecture. This might involve using new programming languages, frameworks, and tools.
4. Testing: You rigorously test the refactored application to ensure it meets the requirements and performs as expected in the cloud environment.
5. Deployment: You deploy the refactored application to the cloud, taking advantage of cloud-native services for deployment, scaling, and management.

Benefits of Refactoring:

• Improved Scalability and Elasticity: Cloud-native architectures enable applications to scale automatically based on demand, ensuring optimal performance and resource utilization.
• Enhanced Performance: Refactored applications can benefit from cloud-optimized infrastructure and services, leading to improved performance and responsiveness.
• Increased Agility: Microservices and other cloud-native architectures make it easier to develop, deploy, and update individual components of the application, increasing development agility.
• Reduced Costs (Long-Term): While refactoring requires a significant upfront investment, it can lead to lower operational costs in the long run due to optimized resource utilization and reduced maintenance overhead.
• Innovation: Refactoring provides an opportunity to modernize your technology stack and incorporate new features and functionalities.

Drawbacks of Refactoring:

• High Upfront Cost: Refactoring requires a significant investment of time, resources, and expertise.
• Complex and Time-Consuming: It’s the most complex and time-consuming cloud migration strategy.
• High Risk: Rewriting the application code introduces the risk of introducing new bugs or issues.
• Requires Specialized Skills: Refactoring requires developers with expertise in cloud-native technologies and architectures.

Use Cases for Refactoring:

• Applications with Scalability Challenges: When the existing application struggles to handle increasing workloads.
• Applications with Performance Bottlenecks: When the application’s performance is limited by its architecture.
• Applications Requiring Modernization: When the application’s technology stack is outdated and difficult to maintain.
• When Long-Term Benefits Outweigh Upfront Costs: When the organization is willing to invest in a long-term solution that will provide significant benefits.

Alternatives to Refactoring:

• Rehosting (Lift and Shift): For quickly moving an application to the cloud without changes.
• Replatforming (Lift, Tinker, and Shift): For making some modifications to the application to leverage cloud services.
• Repurchasing (Drop and Shop): For replacing the application with a cloud-based SaaS solution.

Important Considerations:

• Thorough Planning: Refactoring requires careful planning and a clear understanding of the application’s requirements and goals.
• Skill Assessment: Evaluate your team’s skills and identify any training or hiring needs.
• Incremental Approach: Consider refactoring the application in phases to reduce risk and allow for continuous delivery.
• Testing and Quality Assurance: Implement rigorous testing and quality assurance processes throughout the refactoring process.

💡 Example: Breaking a monolithic application into microservices and deploying it on AWS Lambda, Google Cloud Run, or Kubernetes.

5️⃣ Relocate

While “Relocate” isn’t one of the commonly cited “6 Rs” of cloud migration (Rehosting, Replatforming, Repurchasing, Refactoring, Retiring, Retaining), it can be a useful way to think about a specific type of cloud migration, especially when dealing with physical infrastructure.

Here’s how we can understand “Relocate” in the context of cloud migration:

Relocate: Moving Physical Infrastructure

“Relocate” primarily focuses on the physical movement of your IT infrastructure. This might involve:

• Moving your data center: This could be due to factors like expiring leases, better facilities, or cost savings in a new location.
• Moving specific hardware: You might move certain servers or network equipment to a colocation facility or a different data center.

How it Relates to Cloud Migration:

• Hybrid Approach: “Relocate” often plays a role in a hybrid cloud strategy. You might move some of your infrastructure to a different location while keeping other parts on-premises or migrating them to the cloud.
• Bridge to the Cloud: “Relocate” can be a stepping stone towards full cloud adoption. By moving your infrastructure to a more modern facility, you can better prepare for future cloud migrations.
• Not Always Necessary: In many cases, “Relocate” might not be necessary for cloud migration. You can directly migrate applications and data to the cloud without physically moving your existing infrastructure.

Considerations for Relocation:

• Logistics: Planning and executing the physical move of IT equipment requires careful coordination and logistics.
• Downtime: Minimizing downtime during the relocation process is crucial.
• Costs: There are costs associated with moving physical infrastructure, including transportation, installation, and setup.
• Security: Ensuring the security of your equipment during and after the relocation is essential.

When “Relocate” Might Be Relevant:

• Data center consolidation: When you’re consolidating multiple data centers into one.
• Disaster recovery: When you need to move your infrastructure to a different location for disaster recovery purposes.
• Edge computing: When you’re deploying infrastructure closer to the edge of the network.

💡 Example: Migrating VMware workloads from an on-premises data center to Google Cloud VMware Engine.

6️⃣ Retire (Decommission)

In the context of cloud migration, “Retire” means decommissioning or shutting down applications or infrastructure that are no longer needed. It’s a crucial part of a successful cloud strategy, as it helps to reduce costs, simplify IT operations, and focus resources on more valuable initiatives. It’s not about moving something; it’s about getting rid of it.

Here’s a breakdown of “Retire” in cloud migration:

What it means:

• Identify Unused or Underutilized Resources: This involves assessing your existing applications and infrastructure to find systems that are no longer being used, are redundant, or are underutilized.
• Decommissioning: This involves properly shutting down and removing these resources. This might include:
  • Turning off servers
  • Deleting databases
  • Canceling software licenses
  • Physically removing hardware
• Documentation: It’s important to document the retirement process, including why the resource was retired, when it was retired, and any dependencies it might have had.

Why Retire?

• Cost Savings: Eliminating unnecessary resources can significantly reduce IT costs, including hardware, software, maintenance, and energy consumption.
• Reduced Complexity: Retiring unused systems simplifies IT operations and makes it easier to manage your infrastructure.
• Improved Security: Reducing the number of systems can improve security by minimizing the attack surface.
• Resource Optimization: Retiring old systems frees up resources (budget, personnel, time) that can be allocated to more strategic initiatives, like cloud migration itself or developing new applications.
• Environmental Responsibility: Retiring hardware reduces energy consumption and e-waste.

How to Identify Resources for Retirement:

• Usage Analysis: Analyze server utilization, application usage, and other metrics to identify resources that are underutilized or not being used.
• Dependency Mapping: Understand the dependencies between different systems to ensure that retiring one resource doesn’t negatively impact others.
• Business Requirements: Review business requirements to identify applications or systems that are no longer needed to support business processes.
• Application Portfolio Assessment: Conduct a comprehensive assessment of your application portfolio to identify candidates for retirement.

Considerations for Retirement:

• Data Backup: Ensure that any important data stored on retired systems is properly backed up and migrated to a different location if necessary.
• Compliance: Consider any compliance requirements related to data retention before retiring a system.
• Communication: Communicate the retirement plan to all stakeholders, including users and IT staff.
• Phased Approach: Consider a phased approach to retiring systems to minimize disruption.

Retiring vs. Other Cloud Migration Strategies:

“Retire” is distinct from the other “R” strategies:

• Rehosting: Moving an application to the cloud without changes.
• Replatforming: Making some modifications to an application to leverage cloud services.
• Repurchasing: Replacing an application with a cloud-based SaaS solution.
• Refactoring: Redesigning and rewriting an application for the cloud.
• Retaining: Keeping an application on-premises.

“Retire” is about eliminating resources, not migrating them. It often goes hand-in-hand with the other strategies. For example, you might refactor some applications, repurchase others, and retire those that are no longer needed.

💡 Example: Shutting down an old HR management system after moving to a modern cloud-based HR platform.

7️⃣ Retain

In the context of cloud migration, “Retain” means keeping certain applications or infrastructure on-premises, rather than migrating them to the cloud. It acknowledges that not everything needs to be moved to the cloud, and that some systems might be better suited for an on-premises environment. It’s a deliberate decision based on various factors.

Here’s a breakdown of “Retain” in cloud migration:

What it means:

• Analysis and Decision: This involves carefully evaluating your existing applications and infrastructure to determine which systems should remain on-premises.
• Justification: There should be a clear justification for retaining a system, based on factors like regulatory requirements, performance needs, security concerns, or cost considerations.
• Maintenance and Management: Retained systems still require maintenance, updates, and ongoing management, even if they’re not being migrated.

Why Retain?

• Regulatory Compliance: Some industries have strict regulations regarding data storage and processing, which might require keeping certain systems on-premises.
• Data Sovereignty: Data sovereignty laws might require that certain data remains within a specific geographic region, making cloud migration challenging.
• Performance Requirements: Some applications might require very low latency or high bandwidth that might be difficult to achieve in the cloud.
• Security Concerns: Organizations might have security concerns about moving sensitive data or applications to the cloud.
• Cost Considerations: In some cases, it might be more cost-effective to maintain certain systems on-premises, especially if they are already well-maintained and have a low total cost of ownership.
• Legacy Systems: Older, legacy systems that are difficult or costly to migrate might be retained until they can be replaced or modernized.
• Specific Hardware Dependencies: Some applications might rely on specialized hardware that is not readily available in the cloud.

Considerations for Retention:

• Ongoing Costs: Retained systems still incur costs for hardware, software, maintenance, and IT staff.
• Technical Debt: Retaining older systems can contribute to technical debt, making it more difficult to innovate and modernize.
• Integration Challenges: Integrating on-premises systems with cloud-based applications can sometimes be complex.
• Security Management: Maintaining the security of on-premises systems is an ongoing responsibility.

Retaining vs. Other Cloud Migration Strategies:

“Retain” is the opposite of the other “R” strategies that involve moving to the cloud:

• Rehosting: Moving an application to the cloud without changes.
• Replatforming: Making some modifications to an application to leverage cloud services.
• Repurchasing: Replacing an application with a cloud-based SaaS solution.
• Refactoring: Redesigning and rewriting an application for the cloud.
• Retiring: Decommissioning or shutting down applications or infrastructure.

“Retain” is about not migrating. It’s a valid and often necessary part of a comprehensive cloud strategy. It’s important to make informed decisions about which systems to retain based on a thorough assessment of business requirements, technical considerations, and cost-benefit analysis. A hybrid approach, where some systems are in the cloud and others are retained on-premises, is a common and often effective strategy.

💡 Example: A high-frequency trading system that needs ultra-low latency may remain on-premises while other workloads move to the cloud.

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Choosing the Right Migration Strategy

Selecting the best migration strategy depends on business goals, application architecture, cost considerations, and technical feasibility. Here’s a simplified decision framework:

Migration Need	Best Strategy
Quick move with minimal changes	Rehost
Minor optimizations for cloud benefits	Replatform
Switching to a SaaS-based solution	Repurchase
Full modernization and cloud-native adoption	Refactor
Moving workloads between clouds	Relocate
Removing redundant applications	Retire
Keeping applications on-premises	Retain

Conclusion

The 7Rs of cloud migration provide a structured approach to cloud adoption, ensuring that organizations make informed decisions based on their unique requirements. Whether you are lifting and shifting, re-architecting, or moving to SaaS, selecting the right strategy is key to a successful migration.

🔹 Which cloud migration strategy fits your organization best? Let us know in the comments! 🚀

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