SHARE in Anaheim: The Ugly Truth about Rehosting

If you’re feeling pressure to move your company’s workloads off the mainframe, pause and do a total cost of ownership (TCO) analysis before taking the leap.

That’s the message Innes Read delivered Tuesday during his presentation at SHARE in Anaheim, “Mainframe Rehosting – The Ugly Truth about Costs and Quality of Service!”

Though it may seem like your business will save big by transitioning to a distributed environment, the actual price can be monumental.

Read, an enterprise IT architect at IBM, sees the costly reality every day while performing such TCO analyses with the IBM Eagle Team.

“Of all the studies we’ve done, most mainframe z/OS systems are already the best place to be running for those organizations,” he said. “That may be horribly disappointing to some or great news for others.”

Only very rarely does rehosting reduce costs, he said. And often, it significantly increases them.

One financial services company, for example, was running a midsized workload of 1,660 MIPS, equivalent to six processors, with a five-year TCO of $17.9 million. After the migration, it needed 176 processors to handle the same workload—that’s 29 times more cores than before, at a five-year TCO of $25.4 million.

Part of that skyrocketing cost is associated with software, which is normally licensed by core, Read said. But businesses often neglect to think about those licensing costs when pondering a move off the mainframe.

Rehosting bears another risk in that many companies that start the project never finish, despite making a significant investment. One public company planned to finish its migration in June 2007. More than two years later, it had moved just more than half of its applications and had blown its budget by 536 percent.

“This project was a dismal failure,” Read said. “It ran over by years. The resulting pair of solutions cost more than the single solution did beforehand.”

A better understanding of mainframe workloads and the platform, he said, can prevent companies from starting a rehosting project that will ultimately cost them dearly.

System z, he said, is highly efficient and designed to benefit from statistical multiplexing of many workloads. And if your company needs to run large consolidated workloads, it’s crucial to be able to run mixed workloads.

The consolidation factor, it ends up, is much more important than your hardware’s age or differences in technology. And in that regard, there’s still a big difference between distributed platforms and the mainframe.

Doing a little research will go a long way toward ensuring you’re looking at the right factors when considering rehosting, Read said.

“Look at the costs, understand the costs,” he said, “and do some real math.”

Miss out on SHARE in Anaheim or simply looking to revisit a presentation? More than 25 sessions, including “Mainframe Rehosting – The Ugly Truth about Costs and Quality of Service,” are available for purchase at

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