What Is Mainframe Rehosting and Why Should You Care?

by Moses Mathuram, Vice President of Global Channels and Partnerships

What is mainframe rehosting? It is a solution for addressing the challenges of an aging, expensive mainframe. When a mainframe is not able to meet increasing and ever-changing demands for agility, modern applications and processes, digital transformation, innovation, and cost-effective computing, there are several options for addressing the challenge. You can replace the mainframe with a new one, write new front-ends for its applications, rewrite its applications, convert code, or rehost.

This post defines mainframe rehosting, explains how it works, provides reasons for choosing it, and shares examples of successful rehosting projects.

What Rehosting Is

Rehosting is a cost-effective method of addressing the challenges of maintaining a decades-old mainframe and its applications. Commonly referred to as “lift and shift,” rehosting moves (“lifts”) mission-critical and core applications off the mainframe and migrates (“shifts”) them to new hardware or the cloud. The most comprehensive form of rehosting is sometimes referred to as “replacement,” because the end result is the migration of core mainframe programs onto the modern system.

Other variations of mainframe rehosting are MIPS reduction and re-platforming. MIPS is an acronym for “millions of instructions per second,” and it’s a measurement of computing resource consumption. MIPS reduction offloads high-consumption workloads in mainframe environments onto less costly open systems or the cloud. Re-platforming uses automated tools to convert legacy applications and mirrors their data structures onto an open system or cloud platform. It compiles the programs, translates the sequential files, and installs and configures a new environment.

How Rehosting Works

Rehosting recompiles mainframe applications in a modern open system, such as a multi-tiered, SQL-based x86 environment or the cloud, without changes to the business logic. This new environment runs specialized rehosting software that provides the development and execution environment required by traditional mainframe programming technology. Once the mainframe application is rehosted, it can continue to function with minimal code changes.

The most effective rehosting solution breaks mainframe applications into isolated tiers and provides tools for moving mainframe data to an isolated database tier that supports industry-standard SQL databases. After the move is completed, you can access mainframe data with existing data analytics tools. You also have the choice of supporting mobile with presentation tools that address the application layer.

Why Rehost Your Mainframe?

Why should you consider mainframe rehosting? Here are five good reasons.

• Rehosting your mainframe is fast and low-risk. Mainframe rehosting can take as little as nine months. Also, there are no changes to the underlying business logic or user interface and no negative impact on your enterprise. It requires minimal training, and the system operates the same.
• Rehosting your mainframe reduces costs. Rehosting has been proven to dramatically reduce infrastructure and operating costs. For example, for the financial services arm of a global conglomerate, the costs of running a portfolio management system fell by 66% after rehosting. You can reallocate these cost savings to innovation, such as rewriting legacy apps so they are more flexible, reusable, and able to deliver new customer experiences.
• You can rehost your mainframe with your current resources and skills. Mainframe, COBOL, and PL/I experts are difficult to replace because younger programmers are trained in more modern language and technology. With rehosting, your existing resources with any or all of these skills can be utilized. There’s no need to hire more.
• Rehosting your mainframe offers the opportunity to modernize. Rehosting creates a fast, flexible foundation for quickly responding to market change and future integration requirements with no proprietary lock-in. You can take advantage of modern technology, such as reusable components, microservices, and containers, so you can do more business faster.
• Performance and reliability improve. Your customers and employees expect a super-fast experience. Rehosting creates an environment that dynamically scales based on business demand so that, even during peak processing, your end users experience the same maximum service and reliability.

For more details and examples of these reasons, check out “A Good Night’s Sleep for IT: 5 Reasons to Rehost Your Mainframe.”

Who Is Rehosting?

Curious about companies that have adopted mainframe rehosting? Here are two success stories.

A Major U.S. Retailer Reduces TCO and Increases ROI with Mainframe Rehosting

A major U.S. retailer’s 10 core business systems (9,500 MIPS) were housed in six IBM mainframes. Each year, licensing fees and the costs of maintaining the mainframes and their massive footprint of 93,271 batch processes increased significantly. To reduce costs and become more agile, the retailer chose a rehosting solution for its IMS applications. As a result, the retailer reports, there has been a significant reduction in TCO, a 50% reduction in costs, and an increase in ROI when compared to the mainframe environment.

Mainframe Rehosting Reduces Costs Dramatically for a Global Insurer

The core business system (1,600 MIPS) of a global property and casualty insurance company was housed in an IBM mainframe with a footprint of 19,000 batch processes. After rehosting, the insurance carrier has a lower-cost, more manageable environment. They report enhancements in CPU capability (10,000 MIPS), improvements in transactions per second (4x), a response time of 200 milliseconds, and optimized batch processing. Cost reductions were estimated to be $17.5 million in the first five years after the project.

Ready to Explore Mainframe Rehosting in More Depth?

An industry leader in mainframe rehosting, TmaxSoft OpenFrame offers flexible solutions for your enterprise. In our eBook, Lift, Shift and Modernize: Proven Mainframe Modernization Strategies that Enable Digital Transformation, you can get more details about rehosting options and which will suit you best, along with an introduction to rehosting with OpenFrame.