The 7 Rs of cloud migration are a set of strategies designed to help organizations plan, execute, and optimize their migration projects. The 7 cloud migration strategies are: rehost, relocate, replatform, refactor, repurchase, retire, and retain.
These strategies provide a roadmap for determining the best approach to moving applications and data from on-premises infrastructure to the cloud. The 5 Rs, 6 Rs, and 7 Rs models have evolved over time, with each iteration adding more options and refining the process.
Jump down to a topic in this article:
The 5 Rs model was first introduced by Gartner in the early days of cloud computing when organizations were just beginning to explore the potential benefits of migrating to the cloud. At the time, many businesses were grappling with the challenges of moving legacy applications and data to a new environment, and the 5 Rs provided a useful framework for evaluating different migration strategies.
Over the years, the 5 Rs model has been widely adopted and has become a well-established tool for planning and executing cloud migration projects. However, as cloud computing has evolved and matured, so too have the strategies for migrating workloads to the cloud.
Recognizing the need for a more comprehensive migration framework, AWS expanded on Gartner's 5 Rs model by adding the sixth R, Retire. This additional strategy highlights the importance of evaluating the ongoing value of existing applications and identifying opportunities to decommission or replace legacy systems with more efficient cloud-based alternatives.
The 6 Rs model has been embraced by many organizations as a more complete and flexible approach to cloud migration. It acknowledges that not all applications are equal and that different strategies may be appropriate for different workloads and business requirements.
As cloud computing has continued to mature, and organizations have become more sophisticated in their approach to migration, AWS introduced the 7 Rs model. This latest iteration of the migration framework adds the Retain strategy, which recognizes that not all applications and data can or should be moved to the cloud.
By including the option to retain workloads on-premises, the 7 Rs model provides organizations with even greater flexibility in their migration planning. This allows businesses to balance the benefits of cloud computing with the need to maintain control over critical systems and comply with regulatory requirements.
Let’s look into the “7 Rs” or cloud migration strategies, according to the expanded model introduced by AWS, based on the original “5 Rs” model introduced by Gartner. The image below illustrates the expanded 7 Rs model.
The rehost migration strategy involves leveraging cloud Infrastructure-as-a-Service (IaaS) offerings to redeploy workloads on a cloud instance. The strategy allows enterprises to move an on-prem application and all its dependencies as-is to the cloud.
Without changing the core infrastructure, this approach allows organizations to transfer all application data and workflows to cloud services that match the workload’s existing storage, networking, and compute requirements. Since operational and configuration constructs of workloads remain intact, the rehost strategy is also easy to perform and is suitable for enterprises that lack in-house cloud-native expertise.
The newly introduced strategy involves migrating workloads without impacting ongoing operations, rewriting the application source code, or acquiring new hardware. With this strategy, an enterprise can migrate a collection of servers from an on-premises platform, such as Kubernetes or VMware, to a cloud version of the same platform. An example is managed Kubernetes services like Google Kubernetes Engine (GKE) and Amazon Elastic Kubernetes Service (EKS).
Relocating minimizes downtime and disruption since clients remain seamlessly connected during the migration process. As this strategy doesn’t require significant changes in the configuration and architecture of workloads, it’s not necessary to retrain staff or invest in upgraded hardware, thereby reducing operating expenses. The strategy also makes migration costs more predictable by placing clear limits on scalability.
With the replatform strategy, an enterprise can move an application to the cloud while employing some form of platform optimization to leverage cloud-native capabilities. The application’s source code and core architecture remain unchanged, keeping legacy applications operational while ensuring cloud-based compliance and security.
The replatform migration strategy increases the flexibility, agility, and resilience of workloads while enabling cloud-native capabilities such as automation.
The strategy also saves time and migration costs since enterprises can modernize workloads without rewriting application code. It allows organizations to choose components for modernization, subsequently improving application agility and maximizing ROI. Since the application’s architecture and functionality are retained, teams don’t require extensive training to operate the migrating workloads.
Often considered the most complex migration option, refactoring involves re-architecting workloads to support cloud-native capabilities from the ground up. Although this strategy requires a huge investment in effort and resources, it’s considered the most future-proof migration approach. It allows applications to support advanced capabilities such as serverless computing, autoscaling, and distributed load balancing.
Refactoring helps break down a monolithic application into microservices to achieve high availability and enhanced levels of automation that are often complex to achieve with in-house deployments. While rearchitecting applications for service-oriented architecture may turn out to be costly during the migration phase, a well-planned resulting framework’s operating costs are substantially lower than operating the legacy framework.
The repurchase migration strategy involves swapping internally administered systems for third-party managed services available from the cloud provider. Repurchasing helps teams retire legacy systems and move to a consumption-based, SaaS subscription model that ties IT costs to generated revenue. As the services are built and managed by third-party vendors, the repurchase model reduces operational efforts toward managing infrastructure for in-house teams.
The repurchase option also simplifies and expedites migration while reducing downtime and enhancing scalability and efficient regulatory governance. As the migration approach fully leverages cloud-native capabilities, it’s mostly leveraged for workloads that require enhanced application performance and user experience while minimizing operational overheads.
The repurchase migration strategy involves swapping internally administered systems for third-party managed services available on the AWS marketplace. Repurchasing helps teams retire legacy systems and move to a consumption-based, SaaS subscription model that ties IT costs to generated revenue. As the services are built and managed by third-party vendors, the repurchase model reduces operational efforts toward managing infrastructure for in-house teams.
The repurchase option also simplifies and expedites migration while reducing downtime and enhancing scalability and efficient regulatory governance. As the migration approach fully leverages cloud-native capabilities, it’s mostly leveraged for workloads that require enhanced application performance and user experience while minimizing operational overheads.
This strategy is used when terminating or downsizing applications that are no longer useful in production. In such instances, business-critical workloads that operate on inefficient legacy frameworks are retired as the first step towards the adoption of modern, cloud-native deployments.
This strategy is suitable for applications that cannot be retired and should continue to operate in their existing framework. Enterprises typically decide to retain a workload if it relies on another application that needs to be migrated first or when there’s no immediate business value in migrating the application to the cloud. As for vendor-based applications, an enterprise may also choose to retain if the service provider plans to eventually release a Software-as-a-Service (SaaS) model.
The table below compares the merits, disadvantages, and most appropriate use-case for each migration model:
|
Migration Strategy |
Use-case |
Pros |
Cons |
|
Retire |
Considered suitable for redundant workloads and legacy applications that are no longer in use |
|
Premature or unplanned retiring of workloads may result in incompatibility with interconnected stacks |
|
Retain |
Best for organizations looking to exercise control over their resources and those considering a hybrid cloud migration. Also suitable for applications that are required to run on local data centers for compliance or security. |
|
Acts as a deterrence to adopt modern, cost-effective, secure, and efficient services available in the cloud. |
|
Relocate |
Mainly suitable for applications running on VMware servers and local Kubernetes distributions |
|
|
|
Rehost |
For organizations looking to expedite cloud migration at a fraction of the cost, while looking to eventually add further changes |
|
|
|
Replatform |
For organizations considering a move to the cloud but are concerned about the risks involved in comprehensive migration of legacy apps in one go |
|
|
|
Repurchase |
Organizations looking to leverage cloud-native capabilities without having to design systems from scratch |
|
|
|
Refactor |
Best for complex applications with high-usability and a strong business case for performance optimization. Also, suitable for applications that need refactoring due to changing regulatory compliance or threat landscape. |
|
|
NetApp offers multiple solutions to support organizations looking to migrate enterprise workloads to the cloud:
To illustrate how these solutions work in action, here are some examples of how NetApp can help users apply various AWS migration strategies:
NetApp additionally offers:
Cloud migration is a complex undertaking that requires a thorough analysis of ongoing challenges while also mapping them with the required changes to reach business objectives. Migrating strategies are typically chosen based on the varying complexities of workloads, costs incurred, and the level of disruption they may cause to an existing setup. While a well-executed transition offers numerous benefits, organizations must also factor in the risks and efforts required for ongoing maintenance.
To know more about how NetApp can help with your migration, take a look at our guide to migrating enterprise workloads and read about our cloud migration case studies to see the advantages of moving business-critical workloads to the cloud.