What Is A Legacy System? Risks And Modernization Strategies

  Table of Contents hide What Is A Legacy System? Why Do Legacy Systems Still Exist? What Are The Risks of Keeping A Legacy System? …



The word “legacy system” is frequently used by experts, and it has a lot of negative implications. Some companies believe that legacy systems must be avoided at all costs, while others discover that the majority of their key activities rely on old software or procedures. For example, 42 percent of agencies spend more than 25 percent of their IT spending on maintaining systems that are already outdated.

Furthermore, the Social Security Administration announced in 2018 that they were ready to begin the process of phasing down legacy systems, but that it would take five years to virtually fully eliminate them. This implies that many of their systems are still in use today.

As organizations strive to stay up with changing times, it is critical to understand the systems that support your critical activities. A legacy system consists of more than simply outdated software. What are legacy systems, and is it beneficial for your organization to replace them?

What Is A Legacy System?

What Is A Legacy System?

It is difficult to characterize a legacy system since no one definition is in use. Technically, this category includes some computer systems, programming languages, software applications, and specialized procedures or technologies. However, there are a few features that define a legacy system:

  • Legacy systems no longer receive support and maintenance, despite the fact that they can’t be replaced because they are critical to the operation of the business.
  • They are built on obsolete technology and hence incompatible with modern, more sophisticated alternatives.

That being stated, any technology that can no longer be automatically supported and upgraded is considered a legacy system. It doesn’t even have to be that ancient; a one-year-old IT system may be called one provided it meets the criteria.

Why Do Legacy Systems Still Exist?

Simply because they are difficult to replace, particularly if they power critical business operations in an organization. When you consider the chance of crucial data being lost or distorted, the risk of altering the status quo may be too high. Furthermore, legacy programs sometimes lack technical requirements, making it difficult to build a new system with the same functionality. Not to add the widespread “fear of the unknown” in many companies.

What Are The Risks of Keeping A Legacy System?

With technology advancing at such a rapid pace, it’s not unexpected that IT systems must be upgraded to stay up-to-date. Particularly since they may ultimately become incompatible with more contemporary systems and platforms that may be critical to your organization.

Although legacy systems continue to function, they might be unstable owing to incompatibility as well as a lack of support and maintenance. They are basically transferred from one developer to the next, and the more fixes they have, the more vulnerable they are to security breaches. Not to mention that the performance of such systems is deteriorating, with a rising number of breakdowns. This, in turn, has an impact on the organization’s efficiency and production.

What Is Legacy System Modernization?

Legacy system modernisation is the process of modernizing and improving corporate IT systems in order to improve operational savings, overcome technical limits, satisfy customer expectations, and promote adoption and integration with other systems based on newer technology platforms.

Legacy system modernisation begins when a company is forced to choose between retaining older, more expensive gear that is incompatible with new technologies and undergoing the massive work of redesigning infrastructure to take advantage of a best-fit platform to support its business goals. As a result, CIOs and IT executives must weigh a number of considerations to decide the best time to modernize, where modernisation will have the greatest impact, and how to properly organize the project to minimize business interruptions.

The bare minimum for legacy system modernisation is to achieve like-to-like system parity with operational improvements. The ideal objective is to produce major improvements in performance, agility, and innovation.

7 Legacy System Modernization Approaches

7 Legacy System Modernization

There are seven typical techniques to legacy system modernization, generally referred to as the “seven Rs,” each with its own level of complexity and payback. The best alternative for your company will help you cut expenses while also making your operations more agile. The legacy modernization Rs are as follows:


Completely decommission and replace existing legacy components.

In this method, you totally replace the previous system with a completely new system that takes into account new needs and modified or streamlined business processes. Replace a historical email system, for example, with cloud-based Microsoft 365, or your indigenous CRM system with Salesforce CRM.

Replacing with SaaS outright can be a speedier path to the cloud, but it needs extensive planning. IT teams must plan how old data will be moved and used in the new system, as well as account for the business interruption caused by user training and learning curves. You should also consider assessing enterprise platforms or systems that satisfy the business requirements and hosting them in a contemporary cloud environment.


Materially restructure and optimize legacy elements into a cloud native environment.

A full rebuild is the most time-consuming and expensive option, but it provides the most benefits. For most companies, this is the desirable end state, with many of the other possibilities only acting as stepping stones along the way.

A full rebuild, as opposed to alternative strategies that just partially exploit updated infrastructure, completely redesigns the old system into a fully modernized, cloud native environment. Implementing DevOps approaches and technologies such as containers, service meshes, microservices, immutable infrastructure, and declarative APIs are all part of this. In the long run, the combination of approach and technology allows for greater flexibility, improved performance, and cheaper operational expenses.


Move runtimes to a modern platform.

The replatforming method transfers an application’s components to a new runtime platform with minimal code modifications and the same functionalities (e.g., moving a COBOL-based system from a UNIX or mainframe system to a LINUX or Windows environment).

To adapt to the new platform, developers can make minor modifications to the code without affecting the code structure or the system’s features and functionalities. Compilers that allow you to transfer apps from one platform to another are frequently available. With no effort, a business may benefit from lower infrastructure expenses and increased performance. Furthermore, it is able to draw value from legacy investments.


Deploy old pieces in a new environment (physical, virtual, or cloud infrastructure) without recompiling, editing code, or changing functionality.

By rehosting, enterprises may preserve their investment in legacy systems such as ERP or databases while benefiting from improved performance and security provided by the cloud’s underlying infrastructure.

Rehosting, often known as the “lift and shift” migration method, allows companies to migrate to the cloud more quickly without having to restructure or re-engineer existing systems. An organization migrates its existing ERP system, database, or other workload to the cloud (e.g., moving an SAP system from an on-premises data center to AWS or GCP). This strategy, however, does not fully leverage cloud native technologies, performance gains, or cost savings.


Incorporate new technologies in application layers to take use of cloud-based or other systems, as well as modify code in chosen tiers.

This strategy, which is commonly found in hybrid setups, takes use of modifying sections of the older component to optimize code for greater performance. Often, this involves adjustments on the backend with no significant changes to the frontend of old systems or the functionality provided. Although technical limits may limit what is achievable, this is less disruptive than a complete overhaul.

In this case, a business may migrate a monolithic program’s database to the cloud while keeping the remainder of the application on-premises. As the name indicates, the system’s application architecture is optimized, generally through code modifications. This may involve making backend changes to legacy elements to ensure that legacy systems integrate well with cloud elements. This allows a company to analyze each application component independently in order to select the best-fit platform for increased performance.


Maintain the current environment with no changes or updates.

An impending merger, end-of-life announcement, or other factor may indicate that there isn’t a strong enough rationale for system modernisation. Even if the short-term option is to keep, a long-term strategy should be in place to ensure the sustainability of important functions.

In general, retention is a short-term metric rather than a long-term strategy. Organizations should use caution when using this “kick it down the road” strategy. The longer inefficient, resource-intensive infrastructure exists, the less money and resources are available to invest in innovation.

A retain strategy may need the construction of “connectors” or “bridges” in order to interoperate with other current parts in the organization. Low-tech, tried-and-true AI models like Robotics Process Automation (RPA) may breathe new life into aging systems with little effort and risk.


Shut down the system completely after assessing the workloads, consumption, and business consequences. 

Following an evaluation of the workload, you may decide that it is best to retire the IT system and transition any remaining users to other systems that are already in place. This frequently necessitates process redesign to fill the vacuum in operational procedures left by the retired technology, and it may also provide a chance for better and optimized business processes.

Preparing For Legacy System Modernization

Preparing For Legacy System Modernization

Your system modernization project might involve upgrading just a little but critical backend system that barely creates a glitch, or it could involve a large-scale change that affects the entire business. In both circumstances, it is critical to plan for a legacy modernisation project by concentrating on the following three areas:

Step 1. Assess your maturity

The first step in application modernisation is determining your maturity level. If your organization has never migrated a legacy system and is still in its early stages of maturity, you should likely concentrate on low-hanging fruit, such as multiple instances of the same application, different applications that handle the same business functions, or non-essential or underutilized applications.

Step 2. Build a plan

Collect data on schedules, finances, and business requirements to evaluate where modernization activities deliver the best return on investment. At this level of the modernization planning process, your data, security, and compliance teams, in addition to the IT team, should be involved.

Step 3. Plan ongoing modernization stages

Application modernisation should be a continuous activity that affects all aspects of your IT and business operations. By definition, it entails maintaining the most recent, efficient, feature-rich, and contemporary infrastructure accessible. There will always be areas that can be modified and enhanced because of today’s technological advancement.

Final words

Regardless of what approach you choose to modernize your legacy system, software modernization is a demanding and risky process. However, the results are well worth the risks, especially if you work with a competent team that can help you bring your software into the future. 

If your company doesn’t have the expertise to execute your legacy system modernization project  in-house, it’s best to find a good service provider to help you. 

CMC Global is among the top three legacy system modernization services providers in Vietnam. We operate a large certified team of cloud engineers specializing in Amazon AWS, Microsoft Azure, and Google Cloud who are able to migrate your legacy assets to the cloud in the most cost-effective way and in the least amount of time. 

For further information, fill out the form below, and our technical team will get in touch shortly to advise!