Migration Strategies Basics: Lift and Shift, Refactor, or Replace?

As the pace of technology innovation increases by the minute, companies of all sizes are racing to become more data-driven and efficient. The recent pandemic has only accelerated this process–industry analyst IDG reports that “Application/legacy system modernization” has risen in importance to become a top priority for CIOs in 2022 . Forward-thinking businesses will continue to innovate and compete for decades to come if they use the right mix of modern solutions, techniques, and strategies, becoming more agile and responsive as a result.

Migrating applications to different JVMs, frameworks, operating systems, and infrastructure is often one of the first opportunities identified as part of an overall application modernization strategy. Application modernization begins with a comprehensive assessment of an organization’s application estate, which includes, among other decisions, which applications should migrate to the cloud and how migration fits into your overall modernization initiatives. Although this process can be challenging, new technology makes the process easier and more reliable. 

Gartner specifies application modernization services as those that “address the migration of legacy to new applications or platforms, including integrating new functionality to provide the latest functions to the business. Modernization options include re-platforming, re-hosting, recoding, rearchitecting, re-engineering, interoperability, replacement and retirement, as well as changes to the application architecture to clarify which option should be selected.”

You can measure the success of a company’s application modernization strategy–including its efforts to migrate to the cloud by re-hosting or replatforming–by evaluating how it has changed its products and services to digital environments, along with the acquisition of skills tied to these changes. Companies that have become digitally mature utilize information and communication technologies in a significant part of their activities and have the capability and willingness to modernize their processes, functions, and organization.

Why Do Companies Decide to Modernize Monolithic Applications for the Cloud?

To level set terminology , a monolithic application is defined as “an app that has all or most of its functionality within a single process or container, and it’s componentized in internal layers or libraries.” 

It is this type of mature application that often represents core application functionality and is responsible for a significant percentage of product or service revenue. Making small changes on the outside of this application can bring some limited benefits, but unless the primary business system is targeted for modernization, the most significant benefits of the cloud are rarely achieved: 

  • Improving application performance and scalability
  • Increasing development team velocity, morale, and innovation
  • Eliminating technical debt: “Technical debt is a concept in programming that reflects the extra development work that arises when code that is easy to implement in the short run is used instead of applying the best overall solution.”
  • Improving compliance and security

In general, companies want to enhance the user experience, keep employees productive and motivated, and ensure sensitive data is protected. Their applications would benefit from being in the cloud to scale, secure, and comply with these goals. 

However, when decision-makers run into limitations for new initiatives and processes due to old and outdated applications, they reach a breaking point: They either stay the same and lose competitiveness, or determine that modernizing business-critical applications and development processes must become a priority.

Related: Migrating Monolithic Applications to Microservices Architecture

Assessing Legacy Applications

If the previous sections sound familiar to you, perhaps you want to take the next step in modernizing monolithic applications for the cloud. In this case, Gartner recommends considering the following factors when assessing the value of modernizing legacy applications.

Business fit

Competitors are modernizing their apps and moving them to the cloud or using SaaS for their solutions. This lets them innovate faster, provide a better customer experience, and recruit the best employees. The longer you wait, the more market share they gain.

Business value

Modern applications benefit from modular architectures or microservices, which allow for easy changes with less risk. Customers can benefit from faster value delivery.


Developers are able to add new features faster with modern applications because the development process is accelerated. Automated building, testing, and releasing builds streamline time-to-market processes.


In modern applications, operating costs are significantly lower because they typically operate on a pay-as-you-go model. Using this method avoids both wasting resources and paying to keep infrastructure running during downtime. In addition, the price and overhead of infrastructure management decrease.


In monolithic systems, adding new features is difficult because of tight coupling and dependencies. This sort of complexity is also responsible for the difficulty in decoupling monolithic services and moving from on-premise servers or data centers to the cloud. You have to weigh these pros and cons.


Making changes to complex monolithic systems can have unpredictable downstream effects on unrelated parts of the monolith, which carries a significant risk. Businesses should assess the costs, vulnerability, competitiveness impact, and operational consequences before making a decision.

With these concepts, you will be able to evaluate your applications more efficiently and choose the best approach to modernization. This will allow you to make the right decision for your company.

Related: How to Conduct an Application Assessment for Cloud Migration

Lift and Shift, Refactor, Replace, or Another Option?

If you’ve heard only about lift and shift, refactor, and replace, know there are other ways to begin your application modernization journey. Here are some ways Gartner explains.


This approach makes the application’s features accessible as services through APIs by encapsulating or separating their data and functions.

In other words, the process creates a more modern interface or API for the existing application and its components making it easier to access by other, newer cloud-native applications but doing nothing to modernize the system or improve the architecture for the future.

You may benefit from encapsulation in the short term because it allows you to move your application to a modern API-driven interface without spending time rewriting it. While it’s a gradual transformation, it is also a stop-gap approach that continues to accrue technical debt and slow down innovation. Thus, in turn, this method comes with some risks, too. Monolithic applications are complicated because of their complexity and size. Without decoupling the logic into microservices, you cannot take advantage of the full benefits of the cloud.

Lift and Shift Strategies (Migration)

Simply put, the “lift and shift” method can also be described as another way of saying that an app will move to the cloud. It is a common mistake for companies to categorize their legacy application modernizations under this heading, as it genuinely does not modernize anything. The “rehost” and “replatform” categories above fall under the “lift and shift” label.

The first step in making lift and shift really work is to make sure that the application, which previously operated in the on-premises data center, still has access to the same data and documents once it is in the cloud. You can successfully lift and shift workloads from the data center to the cloud if the access to shared folders remains the same.

Suppose a company did not thoroughly examine its apps before making the “lift and shift” decision, but it still adopted this approach. In that case, it will oversimplify modernization’s goals and merely move technical debt to the cloud without achieving any substantial business benefits.

It’s good to know that you don’t have to make the migration strategy decision alone. Companies can modernize their applications with the most efficient migration strategy thanks to technology. Check out the following section to learn how.


This migration style means making as few changes as possible to the code for it to run on a new platform, such as the most current operating system. Replatforming does not require you to  manipulate the app’s architecture or functionality.

There is no need to undertake a significant development initiative with replatforming, which makes it cheaper. Taking small steps can be beneficial at first, then you can scale up as needed. The approach also allows you to migrate some workloads to the cloud, run tests on a cloud platform, analyze the results, and then move on to other workloads without committing to a lengthy migration process.

You can leverage the cloud effectively using cloud capabilities such as auto-scaling, managed storage and data processing, infrastructure as code, and more.

This method is not without its risks. One of them is the scope of your work can increase the possibility of turning a replatforming project into a much greater refactoring effort. Limit scope and avoid unnecessary changes to reduce this possibility.

Automation is further necessary since you can’t manage cloud workloads manually after replatforming. As a result, it is essential to invest in automation tools to allow for some flexibility when using the application in the cloud.

Rehost (Migration)

Rehosting refers to migrating the application without modifying its code, data, or functionality to another infrastructure, on-premises or in the cloud. 

With rehosting, you can often migrate relatively quickly and test in the cloud in case there is anything wrong. There’s a risk of disruption to business services unless your organization understands this and is ready with enough contingency plans. Additionally, rehosting may lead to poor user experiences early on, which could hurt user retention. 

Replatform (Migration)

This migration style means making as few changes as possible to the code for it to run on a new platform, such as the most current operating system. Replatforming does not require you to  manipulate the app’s architecture or functionality.

There is no need to undertake a significant development initiative with replatforming, which makes it cheaper. Taking small steps can be beneficial at first, then you can scale up as needed. The approach also allows you to migrate some workloads to the cloud, run tests on a cloud platform, analyze the results, and then move on to other workloads without committing to a lengthy migration process.

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Refactor (Modernization)

As opposed to migration tactics like rehosting or replatforming, refactoring is the application modernization process of reorganizing and optimizing existing code. It lets you get rid of outdated code, reduce significant technical debt, and improve non-functional attributes such as performance, security, and usability. 

This modernization strategy matches cloud infrastructure to actual resource requirements, which results in long-term cost savings. Refactoring provides long-lasting ROI by enabling you to scale when required and reducing resource consumption.

Furthermore, by refactoring, you can also adapt to changing requirements since cloud-native, and microservice architectures make it possible for applications to add new features or modify existing ones right away. 

There are a few downsides to consider. First, without automation, this strategy requires a large number of manual resources. It is much more complex than lifting and shifting, so it traditionally has taken much longer for projects to become profitable. You can’t rely on just anyone to refactor because you need a team with advanced coding, automation, and DevOps skills. The code, infrastructure, and configuration are also at high risk of errors. Last, the smallest mistakes in refactoring cause delays, many cost overruns, and service disruptions. Automation can address these issues.

Rearchitect (Modernization)

The design of some outdated applications prevents them from working in the cloud because they are just not compatible. When this occurs, it is prudent to modernize the application in its entirety by rearchitecting it. It takes a lot of coding to move to a new application architecture in order to make the most of the apps’ features. 

With this modernization method, you break up applications into smaller, more manageable pieces for subsequent individual adaptations and development. You can transfer each component, or microservice, to the cloud separately.

In addition to requiring significant adjustments, without intelligent automation and analysis tools to support the architect, this effort will take a great deal longer and cost more than other alternatives. Nevertheless, the benefits include more flexibility, scaling, and control over the architecture.

Rewrite (Modernization)

Using this approach is a good idea when you need to upgrade a business application and  need to alter some of the previous specifications or functionality while retaining others. This is a good approach for companies that have invested significant amounts of time and money in developing their own applications. A business that rebuilds and innovates, can retain its intellectual property and unique selling propositions, making it a good option for them.

During the rewriting process, you will be able to engage with customers once again and make your customized applications even better. Unfortunately, this approach requires substantial time and expense investment, as well as considerable expertise. 


This solution offers to replace the application with a brand new version of the software or SaaS service that will take into account any further requirements, user requests and perhaps even use a different technology stack.

In replacement, you can compare different apps and get the ones that work best for your business. If you find something that works better, you can switch apps relatively easily. With the replace approach, the app’s developer is responsible for updating, improving, and securing your application with the replace approach. This can also help relieve you of other migration concerns.

On the other hand, replacing old systems can be problematic for employee engagement due to users becoming attached to the old systems since they are accustomed to using them. Managing change and collaborating with your user base is vital, or you might have a hard time while they adapt. Without custom apps, you might lose future ROI, and you’ll have little say on future features or updates.

Partnering Strategically to Make Application Modernization Happen

Both migration and modernization strategies can be complex and diverse, as you may have noticed. Determining which one is the best, implementing it, and preventing risks is not a simple process. However, you can choose a strategic partner to achieve the best results.

vFunction is at the forefront of cloud and application modernization. Its goal is to assist leading companies globally in accelerating their journey toward cloud-native architecture and gaining a competitive edge. With a factory model purpose-built for cloud-native modernization, the solution removes the time, risk, and cost constraints associated with manually updating business applications.

The vFunction AI-driven platform enables software architects to rapidly and incrementally modernize their legacy application portfolios and technology leaders to unlock the power of the cloud, innovate, and scale. The vFunction Platform consists of two products:

  • vFunction Assessment Hub: vFunction Assessment Hub analyzes the technical debt of a company’s monolithic applications, accurately identifies the source of that debt, and measures its negative impact on innovation. The AI-powered solution measures app complexity based on code modularity and dependency entanglements, measures the risk of changes impacting stability based on the depth and length of the dependency chains, and then aggregates these to assess the overall technical debt level. It then benchmarks debt, risk, and complexity against the organization’s own estate, while identifying aging frameworks that could pose future security and licensing risks. vFunction Assessment Hub integrates seamlessly with the vFunction Modernization Hub which can directly lead to refactoring, re-architecting, and rewriting applications with the full vFunction Modernization Platform.
  • vFunction Modernization Hub: vFunction Modernization Hub is an AI-driven modernization solution that automatically transforms complex monolithic applications into microservices, restoring engineering velocity, increasing application scalability, and unlocking the value of the cloud. Utilizing both deep domain-driven observability via a passive JVM agent and sophisticated static analysis, vFunction Modernization Hub analyzes architectural flows, classes, usage, memory, and resources to detect and unearth critical business domain functions buried within a monolith. Whether your application is on-premise or you have already lifted and shifted to the cloud, the world’s most innovative organizations are applying vFunction on their complex “megaliths” (large monoliths) to untangle complex, hidden, and dense dependencies for business critical applications that often total over 10 million lines of code and consist of 1000’s of classes.

Through our solutions, software companies can become faster, more productive, and truly digitally transformed. Contact us if you want to see how we can convert your legacy application to a modern, high-performance, scalable, and authentic cloud-native architecture. Request a demo today.

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