The 7Rs of migration—where does mainframe modernization fit? - TmaxSoft
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The 7Rs of migration—where does mainframe modernization fit?

Mainframe modernization is the process of migrating or improving an enterprise’s existing legacy mainframe footprint in the areas of interface, code, cost, performance and maintainability. In some instances, mainframe modernization can encompass the complete migration of code and functionality to a platform that is based on newer technology and/or hosted in the cloud. But some organizations are falling behind. Their leaders urgently need to ask themselves a crucial question: how do I extract more value from my mainframe investment and be ready for digital transformation?

Digital transformation strategies motivate modernization of underlying systems and, more importantly, the applications that reside therein. The challenge, as usual, is deciding which applications and systems to modernize, determining how to modernize, and identifying the destination for modernized applications. This is where organizations can start to develop a migration strategy that includes mainframe modernization. Consider where your cloud journey fits into your organization’s larger business strategy and find opportunities for alignment of vision. A well-aligned migration strategy, with a supporting business case and plan, sets the proper groundwork for cloud adoption success. Amazon Web Services (AWS) has laid out six different migration options that are called the 6Rs.

What are the 6Rs?

A very crucial aspect of developing a cloud migration strategy is to collect application portfolio data and rationalize to determine which of the 6Rs--rehost, re-platform, re-factor/re-architect, re-purchase, retire, and retain--is right for your cloud migration plan.


Rehosting is a migration strategy also known as “lift and shift.” It is a quick solution for migrating to the cloud and moves applications, software, and data to the cloud with little effort. The sweet spot of lift and shift migrations is to identify applications that can take advantage of the cloud without architectural changes. Rehosting may lead companies to re-architecting in the future, once a cloud-based operation is in place. Many migration projects have shown that it is easier to re-architect applications while already in the cloud, as opposed to refactoring an application and then migrating it.


Re-platforming, also referred to as “lift, tinker, and shift,” involves moving legacy applications almost as-is, but replacing some components to take advantage of the cloud capabilities. Re-platforming may lead companies to re-architecting in the future, once a cloud-based operation is in place. In many cases, this could involve switching from self-hosted infrastructure to managed services, allowing you to scale freely on the cloud.


Re-factoring, which can also be referred to as re-architecting or rebuilding, involves breaking down the application’s components into smaller building blocks, microservices and wrapping them into containers for a deployment on a container platform. It is the strategy that usually leads to the highest transformation cost. However, it allows optimized use of the cloud, leading to cloud-native benefits and making the application future proof. In doing so, the affected application is refactored using an alternative application architecture.


Repurchasing is the strategy where the legacy application is fully replaced by a SaaS-solution that provides the same or similar capabilities. The migration effort heavily depends on the requirements and options of migrating live data. Some SaaS-replacements for on-premise products from the same vendor offer an option to quickly migrate data with little effort or even automatically. This option might not be feasible for custom built applications.


The retire strategy relies on applications that need to explicitly be phased out. This makes sense when the business capabilities this application provides are not needed anymore or are offered redundantly. We see this often in those cases where organizations recently went through mergers and acquisitions. Due to legacy operating systems and applications not being supported by cloud environments, you should take the cloud transformation project as a welcome opportunity to screen your application portfolio and reduce obsolete applications on the go.


The retain Strategy, or revisit, means that you cannot migrate the application at this point since you are lacking important information or are hindered by other factors. Unfortunately, there are some applications that if you were to move the cloud, it would not make any sense. For example, this could be due to latency requirements, compliance reasons, or simply because the benefits of a migration won't outweigh the cost and effort to be invested. You should, however, always set yourself a reminder to “revisit” the application because the technical or compliance landscape might have changed.

Relocate: An unofficial 7th R

A company called CloudSoft looked into the initial 6Rs from AWS and claimed there was an additional one. That’s why a 7th R, relocate, shows up in some migration conversations. Now, AWS is thinking about incorporating relocate into their strategies, although they have not done so yet. In this approach, the organization takes the existing system and relocates infrastructure to the cloud without purchasing new hardware, rewriting applications, or modifying the existing operations. This migration scenario is very specific to VMware Cloud on AWS and can be a faster route to the cloud for VMware customers. It requires a significant amount of planning. IT teams must determine how existing data will be migrated and leveraged in the new system and account for the business disruption of user training and learning curves

Where does mainframe modernization fit in the Rs?

There are multiple ways to approach mainframe modernization. How you proceed will vary based on a range of factors, and much depends on what resources are available and what goals the agency seeks to achieve. The adoption of mainframe modernization as an approach for updating decades-old legacy systems and applications is growing. Modernizing your mainframe, which also improves strategic services in marketing, finance, sales and other areas of the enterprise, is the most dependable option. It can quickly pay off with cost savings, greater flexibility, and adaptability to quickly changing demands from employees and customers who expect instantaneous, highly personalized experiences similar to those on their mobile devices.

Originally, when companies began to first look into mainframe modernization, they believed rehosting to be the only option. This strategy is a widely chosen due to the relatively low migration effort. The virtual machine and the application that runs in are simply copied as-is to a managed mainframe environment or vendor specific cloud environment. The most important benefit of this strategy is migration speed because no architectural refactoring needs to be done. Moreover, the migration can often be done automatically using a variety of lift-and-shift or so-called workload mobility tools.

However, rehosting has a major drawback. Using this approach, the applications are not decoupled from the operation system and restricted in terms of vendor choice. It is not possible to exploit the cloud's entire potential since the applications are not built in a cloud-native fashion. Simply rehosted applications are, compared to cloud-native applications, not decoupled from the operating system and are usually much more difficult to scale. Experience shows that from a cost perspective, rehosting usually does not lead to any major advantage. In order for the mainframe modernization to be successful, it is imperative to not only rehost, but re-platform and re-factor as well.

Mainframe modernization has its own Rs

There are three paths for enterprises embarking on this mainframe modernization journey, depending on the maturity level they plan to reach: reducing MIPS, retiring legacy orphan apps, and replacing the mainframe.

Reducing MIPS by re-platforming

MIPS, an acronym for million instructions per second, is a measurement of CPU resource consumption most often associated with batch processing and online transaction processing. When you consider how long your mainframe and its applications have been running, it is highly likely that your MIPS measure in the thousands and perhaps in the tens of thousands. The first path to mainframe modernization is to figure out how to reduce MIPS. Organizations can drastically reduce MIPS consumption by identifying high consumption workloads in their existing environments and offloading these workloads onto the cloud. If your organization decides to go this route, it becomes proactive, able to identify and address problems before they happen. By re-platforming your high MIPS consuming workloads, you can reuse the original business logic and other assets from your current mainframe system.

Replacing the mainframe by re-platforming first and then re-factoring

Sometimes an organization’s mainframe has been around for so long that its apps and systems are draining resources and slowing software and application performance. This second path solves that problem in two steps. First, it lifts and shifts all the applications residing in a single mainframe to the cloud. Once there, the applications—or a large part of their code base—is re-architected to take advantage of cloud-based features and the flexibility and elasticity that comes with them. As a result, the full value of mainframe apps can be unlocked and exposed as mobile and digital applications that are more agile and responsive to customer expectations and business changes.

No matter which R, there’s a mainframe modernization that’s right for you

Mainframe modernization with TmaxSoft can transform user experiences and unlock the value of your mainframe apps by with comprehensive technology support and platform flexibility, which enables you to choose cloud, on-premises, and container deployments. Because the operating systems are open with multiple database and utilities options, they integrate well with the newer technology required. Check out our eBook to learn more.