IBM taps Linux for mainframes

Boas Betzler, leader of the mainframe Linux project at Big Blue, used a famous mountaineering line to describe the impetus at the LinuxWorld Conference and Expo here. Betzler said he and a handful of other programmers got started on the project in late 1998 "because it was there."

But now, the formerly unofficial project has grown to be more than just a curiosity. It's now an official component of IBM's S/390 mainframe strategy, uniting one of the most radical elements of the computing landscape to one of its most traditional.

In fact, IBM now believes running Linux on a partition of an S/390 will be useful for customers as big as Salomon Smith Barney and Schwab, said Irving Wladawsky-Berger, the newly appointed head of the IBM effort to bring Linux to all four of its server lines. There are several pilot S/390 Linux projects under way, he said in an interview.

The reason to use Linux on a mainframe is to make processes ordinarily on outside servers run faster and be more secure, Wladawsky-Berger said.

IBM is showing Linux running on an S/390 at the expo. "It's a real deal, running on the metal," said Edward Gauthier of the S/390 division.

The S/390 with Linux is a stark illustration of how far Linux has come since Linus Torvalds started the project in 1991 and since the mainstream computing industry started paying attention in 1998.

Torvalds, who long has joked that his ultimate goal for Linux was "world domination," yesterday said he was surprised by the appearance of Linux on an S/390 mainframe.

"This is not something I envisioned back when I started. I didn't envision that a year ago," Torvalds said yesterday during a keynote address.

As previously reported, the extra software needed to run Linux on an S/390 has been incorporated into the heart, or kernel, of Linux.

IBM engineers weren't the only ones to try to bring Linux to the S/390. Linas Vepstas had his own project, called "Bigfoot." However, the IBM effort was done independently--not the typical open model for open-source programming. When IBM's software was released, Vepstas wrote on his Web site, "Because (the IBM) port was done in secret, without contact with the outside world, it is completely incompatible with the first."

Mainframes are powerful servers that predate most computing systems available today. Unlike most of today's computers, mainframes use a powerful separate system to handle communications between the software and the storage disks, enabling very high-speed transactions such as recording a sale in a database.

While many predicted the demise of the mainframe because of the expense of buying and maintaining them, their reliability and transactional speed has made them popular for some types of Web sites such as online trading companies that can't afford not to stay up and running.

The S/390 systems can be divided into several "logical partitions," essentially separate computers running at the same time on the same hardware. Linux runs alongside the traditional OS/390 operating system and is able to communicate quickly with the rest of the system, Wladawsky-Berger said. The technique allows many different Linux systems to run side by side on the same S/390.

IBM believes Linux is a key part of the software needed to run corporate Internet sites. Sun Microsystems, however, isn't such a big fan and instead is pouring its energy into improving its Solaris operating system. Chief operating officer Ed Zander disparaged IBM's approach two weeks ago during a conference call.

"It's amazing to watch as IBM chases down the Linux path the way they did with Windows" four or five years ago, Zander said.

IBM has its own version of Unix, called AIX, which most agree is well advanced over Linux in terms of features such as support for multiple CPUs in one system. So why use Linux instead of AIX?

For one thing, that would have been harder because AIX is more tightly wedded to the underlying hardware than Linux is, Wladawsky-Berger said.

"That's where open source makes all the difference," Wladawsky-Berger said. Linux, designed to run on numerous different chips, is built up from modules and "is ideal to be ported across many platforms." IBM could have done the same thing with its AIX version of Unix, but "that would have been a lot harder," he said.

The port to Linux was relatively simple, Betzler said. The main addition required was a software module that lets the input-output system for Linux communicate with the S/390's particular hardware.