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Replacing vs. maintaining legacy systems

Understanding issues such as which systems hinder organizational performance can help IT leaders decide which legacy systems to replace and which to maintain.

Few CIOs escape the complexity of deciding whether to maintain legacy systems or replace them altogether. The right choice, as with most things in life, is: It depends.

IT leaders might want to replace a legacy system because of outdated hardware, increased security risks or a desire to enable a digital transformation initiative. But replacing existing systems isn't always in the company's best interest. Legacy systems can remain in place if the existing system is reliable.

CIOs and IT leaders should consider the benefits and challenges of replacing vs. maintaining legacy systems.

Prioritize a strategic assessment

One alternative to completely replacing or maintaining legacy systems is to modernize them. Modernized systems might be more cost-effective, while increasing efficiency and improving existing processes at the same time.

Michael Bradshaw is currently working through a multiyear plan to modernize the technology at Kyndryl, a New York-based IT services company.

After about two years of planning and execution, the goal is to complete the big moves by November, he said. A strategic assessment of the company's existing systems and applications was the first step in the process.

His modernization plan calls for the digitalization of the company's entire business chain, Bradshaw said. Previously, about 1,800 applications supported that chain, but the number should drop to 360 by year's end and eventually down to 300.

His IT team partnered with the business to develop a target, as well as a roadmap on how to get there, he said.

The goal of this strategy is to streamline the modernization efforts.

The strategic assessment enabled IT to identify what legacy systems to immediately target for modernization and which could wait, Bradshaw said.

A focus on competitive advantage helped steer the roadmap, too.

"Ultimately, all the systems we provide are to support the execution of business, so you start with the business needs, what's most important for the business," he said.

Organizations that want to modernize must choose systems that support their objectives.

The company considered cybersecurity concerns, maintenance requirements and operational costs to determine which apps to prioritize for modernization, Bradshaw said.

Replacing vs. maintaining legacy systems

Many organizations still rely on legacy systems for some of their workloads, which can limit innovation efforts.

Seventy-two percent of all respondents believe that their organization's digital transformation efforts are lagging due to technical debt, while 51% cite a complex legacy IT infrastructure as one of their key challenges over the next year, according to the 2023 report "CIO Pulse: 2023 budgets & priorities" from cloud software provider SoftwareOne, headquartered in Milwaukee.

Yet, many CIOs don't always have a well-formulated path forward. A good portion of IT leaders are unclear on what they should modernize first and what legacy systems are OK to keep running.

Some might end up shedding a legacy system under duress, said Joe Davey, partner at West Monroe, a digital services firm, headquartered in Chicago.

"Often, it takes a catalyzing event," Davey said.

In some cases, CIOs replace legacy technologies without a clear strategy in mind.

"[The strategy is] technology for technology's sake," he said. "[But] there's a lack of understanding how that technology can help them get ahead."

Although companies eventually need to replace all legacy technology, CIOs don't need to modernize all systems at once -- nor is an undertaking of that magnitude usually possible. Instead, CIOs must determine what legacy systems need to be replaced sooner and which can be replaced later, both Davey and Bradshaw said.

5 reasons to replace legacy systems

Organizations should carefully evaluate their existing systems before making any changes. IT leaders should understand the following reasons why legacy systems should be prioritized for modernization.

1. The system creates an unacceptable security risk

Many IT teams can't patch some legacy systems because vendors don't release new patches. Other systems have significant security vulnerabilities IT can't address for another reason.

Any such system with "security vulnerabilities that could bring the [organization] to its knees should be a high priority for replacement," said Dave Powner, executive director of the Center for Data-Driven Policy at Mitre Corp., a nonprofit research and development organization, based in McLean, Va., that provides technical and cybersecurity support to U.S. government agencies.

2. The system hinders the organization's performance

Inefficient systems can cause delays and decreased productivity.

Organizations should prioritize replacing systems that affect efficiency, said Mihir Patel, vice president of cloud architecture at Apps Associates, a consultancy and MSP, headquartered in Acton, Mass.

Enterprises can pursue new opportunities or significantly improve mission capabilities by modernizing legacy systems, Powner said.

3. The system doesn't fit into the organization's future state

A legacy system without immediate problems can still be a priority for modernization if the processes it supports aren't critical for the organization's long-term goals.

When developing a modernization strategy, CIOs should focus on where the company wants to be, said Suneel Ghei, principal research director at Info-Tech Research Group, an IT services management company, based in London, Ont.

4. The system costs too much to maintain

All systems come with run costs. In some cases, a system's maintenance costs might exceed its business value, including the cost of modernizing the system.

Excessive run costs draw resources away from pursuing innovation and new opportunities, Patel said.

CIOs need to do that math and know when they're approaching or have gone past that point so they can take appropriate action.

5. The system is at a high risk of failure

Systems with no vendor support, that depend on obsolete programming languages or are highly customized with scant documentation and no remaining institutional knowledge of its buildout are highly fragile. Organizations could have a difficult time recovering if the system should fail.

For example, some businesses have needed help with IT systems but couldn't find IT talent to service the systems. It's best to replace those systems before that happens to ensure business continuity.

3 reasons to maintain legacy systems

Companies can maintain legacy systems under the right circumstances. Here are three reasons to maintain a legacy system that IT leaders should understand.

1. The system has an acceptable level of risk

A system no longer supported by a vendor or built on an obsolete programming language does have security vulnerabilities. But it might not create unnecessary risks.

For example, a company might rely on the system for a noncritical back-office function. There would be minimal effects on daily operations if the system failed.

Or the CIO might have or could easily access the talent needed to keep it running at a reasonable cost.

In such cases, the CIO might reasonably opt to make modernizing that system a lower priority.

2. The system still supports the organization's needs

A system that meets the organization's needs, while not hindering its ability to pursue new competitive opportunities, is a strong candidate to stay in place.

Organizations might do themselves a disservice by replacing legacy systems with modern versions they're not ready to use or optimize, Patel said.

For example, replacing an existing system with a modern app featuring AI might seem like a good strategy. Still, a company needs to have the maturity required to use the AI component successfully to get ROI that justifies the modernization.

3. The system's processes can be sunsetted or shifted to other systems

Maintenance makes sense when the organization's long-term strategy doesn't include the legacy system in some way.

CIOs might opt to keep a legacy system in place if they know that the business processes it supports will be sunsetted by the organization or shifted to other systems, said Nitin Naik, technical fellow at Mitre Corp.

Replacing a system that won't be needed in the future won't deliver good ROI.

Next Steps

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How to perform an application modernization assessment

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