By Stuart Dee
Throughout my career as an Enterprise Architect, I have consistently seen organisations chase three strategic goals: improving efficiency, optimising costs, and accelerating innovation. This pursuit has brought a powerful paradox to enterprise IT. The very systems once labelled outdated, often dismissed as “strategic technology debt,” are now proving to be an essential foundation for modern digital transformation.
Initially unfamiliar with mainframe technology, I was quickly impressed by their remarkable reliability, robust security, and exceptional capacity for handling immense transaction volumes. As digital transformation has accelerated, mainframes are no longer seen as relics, but as strategic assets ripe for evolution.
A 2024 BMC study revealed that 94% of participants hold a positive view of mainframe technology, seeing it as a sustainable, long-term platform. Similarly, the 2024 Planet Mainframe survey found that a quarter of organisations are actively developing or implementing AI and machine learning models directly on their mainframe infrastructure. Furthermore, an IBM Institute for Business Value report indicates mainframes are considered equal to or even better than cloud computing in terms of total cost of ownership (TCO).
The Transformation Philosophy
The core of mainframe transformation is not necessarily about wholesale replacement; it is a strategic philosophy centred on extracting and evolving the valuable business logic locked within heritage systems. It is about viewing decades of investment not as a sunk cost, but as a deep well of institutional knowledge.
The modernisation journey typically begins with thorough exploration and evaluation, a form of digital archaeology. Organisations must first map the complex relationships between user interfaces, COBOL applications, JCL procedures, and data structures. This initial stage is crucial for identifying obsolete code, uncovering operational clusters, and establishing the groundwork for the most suitable modernisation approach.
Strategic Modernisation Approaches
To help organisations navigate their options, Gartner offers a widely recognised framework: the “7 Rs of Application Modernisation.” For mainframes, the most common and effective strategies tend to be Replatform, Rearchitect, and a powerful combined approach often called “Hollow out the Core.”
Replatform – “The Lift-and-Shift” Strategy
This approach involves migrating existing mainframe workloads to modern cloud environments using hardware and middleware simulation tools. This enables rapid transition to cloud infrastructure whilst preserving existing application logic. Everything remains the same, making this the most conservative modernisation strategy and providing time to prepare for the next phase of transformation.
Rearchitect – The Microservices Transformation
A more profound path is to completely redesign applications into a modular microservices architecture. For instance, legacy COBOL batch operations can be rewritten as modern Java Spring Batch workflows, and hierarchical IMS repositories migrated to relational databases. This approach delivers enhanced application scalability, improves development agility, and offers better integration built on modern architectural patterns.
A Combined Strategy – “Hollow out the Core”
This increasingly popular approach combines the best of both worlds. Organisations retain the mainframe for its unparalleled transactional strengths and stability whilst migrating peripheral applications and services to modern platforms. This strategy provides a gradual, low-risk path, preserving core system stability while modernising non-critical workloads, leading to optimal resource allocation and a phased journey to a hybrid future.
Containerisation: Bridging the Divide
A significant recent development in mainframe modernisation is the widespread adoption of containerisation technologies. Modern mainframes now support containerised workloads, allowing organisations to run Linux containers natively on z/OS. This effectively bridges the gap between traditional mainframe applications and contemporary cloud-native development practices.
Containerisation on the mainframe is particularly valuable for hybrid architectures. It allows enterprises to keep core transactional processing on the mainframe whilst deploying supplementary services in lightweight, portable containers. This approach facilitates easier integration with modern DevOps pipelines and supports the deployment of modern development frameworks alongside existing COBOL applications.
Navigating the Journey: Challenges and Success Factors
Despite compelling benefits, mainframe transformation demands meticulous planning across multiple dimensions. Critical success factors include assembling expert teams with dual expertise in legacy mainframe systems and modern technology stacks, supported by robust automation tools and comprehensive transformation platforms.
However, the cornerstone of success remains a well-defined strategy that directly aligns with business objectives whilst addressing resource limitations. Replatforming offers a particularly attractive solution to the mainframe talent crisis, enabling organisations to tap into the more readily available pool of cloud-native expertise whilst safeguarding existing business logic. This strategic pause creates breathing space to evaluate current capabilities and develop thorough modernisation roadmaps.
Each modernisation approach carries distinct complexity and risk profiles that fundamentally shape the transformation journey.
Conclusion
Mainframe transformation is not a demolition project; it is a journey of renewal. The evidence shows mainframes are experiencing a renaissance, transforming from a traditional monolithic form into a modern, AI-enabled, containerised platform. This evolution respects the heritage of solid infrastructure whilst fully embracing the future of flexible, cloud-native enterprise IT. The key to success is selecting the appropriate modernisation strategy that aligns with an organisation’s unique business objectives, technical constraints, and long-term vision. The mainframe paradox has been solved, it is no longer a burden, but a powerful digital enabler.
If you would like to find out more about how I can assist in your mainframe modernisation, please reach out for a chat.