Posted: 18 Apr. 2022 5 min. read

Modernizing your mainframe: Migrate to cloud

A blog post by David Linthicum, chief cloud strategy officer, Deloitte Consulting LLP 


Cloud technologies have been revolutionizing industries for quite some time now. Though the idea of finally migrating your mainframe to the cloud can be daunting, it has become crucial for businesses to run seamlessly.

Migrating from legacy systems to cloud

Mainframes hosted in datacenters are still the backbone of many organizations, especially in government and financial services organizations, but this setup tends to hinder them from upgrading monolithic legacy applications running on mainframes to their modern counterparts. Plus, finding the right resources to manage and maintain the mainframe is no easy task. There is a real talent shortage, particularly of those possessing the right skills to understand complex systems of mainframes. Mainframe operations demand a premium to run and manage, making it an expensive, unreliable, and complex resource to sustain for the long term.

Migration, therefore, can help reduce costs and increase efficiency. Customers benefit from this modern infrastructure or move to the cloud with improved reliability and resources.

Assessing the right strategies

When migrating from mainframe to the cloud, assessing the market for the different available technologies helps ensure the task is performed efficiently and sequentially. Customers moving from on-prem to cloud undertake one of three primary methods.

  1. Hardware emulation – Rehosting the mainframe system to the cloud, wherein all the coding and compilation has to be translated as per the systems offered by the cloud provider.
  2. Middleware emulation - In this method, the complete system is migrated to the target side without any modifications. The middleware emulator prepares the pre-requisites for applications to compile on the target location.
  3. Automated refactoring – One of the most sought-after migration patterns, automated refactoring, preserves the business functionality and helps attain functional equivalent. This can transform the entire software stack; for instance, the code from COBOL, RPG, or PL1 is transformed to a modern programming language like Java or C#.

Apart from these methods, another viable option for migrating mainframe applications to the cloud is manual rewrite, although it is the least popular and least preferred method.

Automation is the ‘next big thing’

Though most companies have already migrated their legacy applications to the cloud, it is imperative to use automation to finish the journey. Automation can assist in processing the transition to the new environment in the cloud and even running those applications in a risk-free manner. It is also easier to create test cases in an automated environment using the right tools and methods to ensure that the application is executing the functions and solving the business problems exactly the way it performed in the mainframes—and perhaps, even better post-migration to the cloud. It is really just a matter of time before the majority will migrate to the cloud, and automation will be the go-to method.

While the challenges are myriad, they are not insurmountable. Knowing about the right tools, having a sound knowledge of the business objectives and how those align with the technical requirements and the modernization options for mainframe applications, and undertaking continuous test scenarios to de-risk the overall migration process are some of the core components to realize a successful migration to the cloud with minimal interruption.

Learn more about this topic by listening to our On Cloud podcast by David Linthicum.


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David Linthicum

David Linthicum

Managing Director | Chief Cloud Strategy Officer

As the chief cloud strategy officer for Deloitte Consulting LLP, David is responsible for building innovative technologies that help clients operate more efficiently while delivering strategies that enable them to disrupt their markets. David is widely respected as a visionary in cloud computing—he was recently named the number one cloud influencer in a report by Apollo Research. For more than 20 years, he has inspired corporations and start-ups to innovate and use resources more productively. As the author of more than 13 books and 5,000 articles, David’s thought leadership has appeared in InfoWorld, Wall Street Journal, Forbes, NPR, Gigaom, and Prior to joining Deloitte, David served as senior vice president at Cloud Technology Partners, where he grew the practice into a major force in the cloud computing market. Previously, he led Blue Mountain Labs, helping organizations find value in cloud and other emerging technologies. He is a graduate of George Mason University.