Linux has long been the perennial bridesmaid of the computing world: Good enough to drive Web servers and other front-end applications, as well as being a favorite with academics, but not steady enough to pair with most companies' critical back-end operations.

Proponents have argued recently that the situation is changing. This year, the open-source operating system may be closer to making big inroads into the enterprise, with a slew of brand-name vendors introducing products and services for advanced Linux-based computing models.

IBM, which got behind Linux about two years ago, says the operating system underpins the future of grid computing, under which all computers inside a company, from desktops to mainframes, are linked by intelligent software that can direct processing power to where it's most needed. The type of load balancing required for such a model will work only in a totally open-source environment, says Ross Mauri, VP for eServer development at IBM. "There's no way of connecting all the heterogeneous systems you would typically find in a corporation into a usable grid," he says.

IBM will begin releasing products designed to enable commercial grid computing as early as this year, starting with load-balancing software for Linux. How serious is the vendor about open source? It's conceivable that IBM could ditch all of its own operating systems, including zOS and AIX, in favor of Linux within five years "if that's what customers want," Mauri says.

No one says businesses will soon dump everything in favor of Linux, but the fact that IBM concedes there may be a time when it's the only operating system IBM ships is surprising, considering the millions of dollars the vendor has spent developing Unix systems in the last decade.

Hewlett-Packard expects "a breakout year" for Linux, CEO Carly Fiorina says. This spring, HP will add Linux systems to the pay-per-use programs it offers Windows and Unix users. Under the program, HP assumes full life-cycle management of a customer's servers, and customers can dictate the size of their infrastructure based on computing needs. HP is also enhancing its broader Linux services; for example, it will offer Linux porting and migration services, along with security and telecommunications application services.

Dell Computer last week unveiled a partnership with Cray Research to offer services that will let business customers of its Intel-based servers create the kind of supercomputing clusters normally associated with multimillion-dollar mainframe and Unix systems. The services will be available for Windows and Linux.

Linux distribution pioneer Red Hat Inc. last month launched new enterprise services aimed at making it easier to deploy and manage Linux installations over the Web. Later this year, Red Hat will unveil an Advanced Server edition of its software with features such as improved clustering and load balancing that are ordinarily found in expensive, commercial operating systems. SAP last week endorsed Linux distributor SuSE Linux's 2.416 kernel for use with its MySAP ERP program.

Linux proponents say the operating system's open-source status gives businesses more flexibility to shape IT infrastructures as they see fit. But critics say the fact that Linux is controlled by the open-source community means that updates and patches won't be predictable, a problem for business users that need to update systems on a timetable. Indeed, Internet user groups of late have been abuzz with complaints that Linus Torvalds, who invented Linux and retains the right to release official updates to the core kernel, is too busy with other commitments to manage the process effectively.

Tony DiBitetto, director of global telecommunication and desktop services at Eastman Kodak Co., says multinational companies such as Kodak need to be able to implement software upgrades and service packs on a predictable schedule. "We don't yet know the implications for sourcing, quality, and how to operationalize Linux," DiBitetto says. "We're looking at it, but right now it's just thoughtware."

Linux's open-source status and its Unix roots appealed to Western Geco, Venkataraman says.

Such concerns don't seem to bother Western Geco, the world's largest seismic services company, which is building clusters of Linux-based Dell PC servers to run computer-intensive research algorithms. Western Geco, a unit of Schlumberger Ltd., has eyed Linux for some time, but it's only in the last year that the Sussex, United Kingdom, company felt it was ready for its IT environment, says Kannan Venkataraman, area manager for worldwide computer systems and support. Linux's open-source status, combined with its Unix roots, was a big draw. "A lot of the tools that we used in the Unix environment port to Linux very easily," Venkataraman says.

E-Trade Group Inc. was also attracted by Linux's open-source status (see "E-Trade Taps Linux For New Web Site"). The company last month said it was switching from Sun Microsystems to IBM Intel-based servers running Linux to power its new Web site. Chief technology officer Josh Levine says he wanted to continue working with Sun, but Sun didn't have open source. "What's happened in the past is that you had to line up with a hardware vendor because of their operating system," he says. "With Linux, we can run our code and if we decide to swap out a vendor, there's no harm done."

Some say moving to a platform that has yet to prove itself as an operating system fit for crucial applications may be risky. Levine thinks otherwise. Linux was ready a year ago, he says, but E-Trade held off on its decision to implement the operating system because of the vendors. "We were looking for the hardware manufacturers to come out and support it, patch it, run it, and be accountable," he adds.

By year's end, Linux installations will capture 32% of the Intel server market, up from 27% last year, according to International Data Corp. Even Sun, which may have the most to lose from Linux's growth, is embracing the operating system at some level. The company is making its iPlanet Application Server work on Linux servers and releasing a version of Star Office for Linux.

E-Trade and other major companies also are looking to Linux for savings. About 5% of the business units within electronics manufacturer Philips N.V. that run their Web applications on Intel systems do so using Linux rather than Windows. Richard Bogues, who runs the company's data center in South Plainfield, N.J., says his internal customers like the idea of running a Unix variant on low-cost Intel systems.

"Intel systems are getting more and more powerful," he says. "On the other hand, running Unix on RISC is still very expensive by comparison."