InformationWeek

The most dramatic example of the open-source operating system's move up the enterprise-computing food chain is the debut earlier this year of Linux for IBM's S/390 mainframes. With IBM's blessing and support, corporate IT departments can now run Linux apps on their big iron, using the available mainframe processing cycles to cost-efficiently meet their companies' E-business requirements.

"When I learned last fall about the possibility of running Linux on our mainframe, my eyes lit up right away," says Rich Smrcina, systems software specialist at Grede Foundries Inc., a $600 million producer of metal castings in Milwaukee. "There's just so much we can do."

Smrcina had been after IBM to bring some of its top apps, including Domino and DB2 Universal Database, to Virtual Machine, the operating system that Grede runs on its S/390 MultiPrise 2000 mainframe. But IBM never showed any indication of doing so. "They have that stuff running on OS/390, but it doesn't make economic sense for us to migrate to OS/390 just to get to those applications," Smrcina says. Such a migration would mean expensive OS/390 licensing fees and would force the company to repurchase OS/390 versions of many of its mainframe apps. The change in operating system would have also resulted in steep retraining costs. "It would be a financial nightmare for us," Smrcina says.

With the availability of Linux for his IBM mainframe, Smrcina now has access to all the applications he originally wanted-and more. "The fact that Linux for System/390 is source-compatible with Linux's existing software base is a tremendous benefit," he says. "I can download anything off the Internet, recompile it, and it works flawlessly most of the time." Among the applications that Smrcina has loaded on his mainframe: the popular Apache Web server; Bind, a Domain Name Server application; and Samba, which lets Unix servers appear as Windows NT machines to Windows clients.

Smrcina says he has good reason to run processes such as DNS and Windows NT emulation on his mainframe. For one, they don't consume many processing cycles, so they ride at virtually no cost on the mainframe's spare capacity. Smrcina also gains his mainframe's reliability. "It's the ultimate in high availability that you can achieve without actually moving to a clustered solution," he says.

Perhaps most important, Smrcina can reduce the number of servers on his network. "Instead of having three additional machines that I have to configure and maintain, I'm just making better use of one I already have," he says.

As he brings more applications onto his Linux for System/390 platform, Smrcina will continue to eliminate Unix, Linux, and Windows NT machines. Such server consolidation does more than just reduce system-ownership costs; it also lets application processes communicate with each other over the high-speed internal networking within the mainframe, instead of over LAN connections. "That architecture results in significantly higher performance and eliminates several potential points of failure," Smrcina says.

Bill Claybrook, research director for Linux at consulting firm the Aberdeen Group, echoes Smrcina's perspective on Linux for System/390. "Server consolidation makes a lot of sense if you have extra cycles on your mainframe," Claybrook says. He also points out that most enterprise data worldwide still resides on IBM mainframes. "If you access that data from Linux applications running on that same machine, you'll get better performance and you'll have better security than you would if you're running that application on a separate server,'' Claybrook says.

"It's a false perception that putting PCs on people's desks will ease the administration burden,'' says Phillipe Welsh, a systems administrator at Cassens Transport Co., a trucking company in Edwardsville, Ill., whose desktop applications are accessed from workgroup Linux servers (see story, p. 98). "We give our users all the benefits of standard PC and browser apps without the PC support hassles."

In addition to finding a home on the mainframe, Linux has also become a popular operating-system solution for high-end clusters. At $25 billion defense contractor Lockheed Martin Corp., Linux clustering technology has been used as an alternative to conventional supercomputing applications. Jeff Layton, a senior engineer, is part of a core group that offers expertise in structural engineering, aerodynamics, and flight control to the company's various aircraft programs. "We do a lot of very heavy computation," says Layton. "Linux has been extremely useful in accomplishing our goals in a fast, cost-effective way."

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