Santa Clara, Calif.-based Sun specializes in servers, higher-end networked machines that run 24 hours a day handling chores such as delivering e-mail or recording credit card charges. Sun's continued support for its lower-end servers isn't necessarily a new competitive strategy for the company; however, the incorporation of Linux represents the first time Sun has supported another operating system besides its own Solaris version of Unix.

The new servers will pack two processors into a single 1.75-inch-thick enclosure about the size of a pizza box, a first for Sun in its efforts to pack more computing power into less space. Later this year, Sun is expected to take the next step, introducing super-thin "blade" servers stacked in a single enclosure, similar to books in a bookshelf.

Sun Chief Executive Scott McNealy is scheduled to announce the new servers Aug. 12 and its Linux plans Aug. 13 in the opening keynote of the LinuxWorld Conference and Expo in San Francisco, according to an advisory and a Sun representative.

"You're going to see a great big new Linux world out of Sun," McNealy said in July after Sun reported its latest financial results--a brief show of profitability despite eroding profit margins.

The moves are critical for Sun as it seeks to stave off competition from Intel, Microsoft and their allies. Linux has put pressure on Sun's arch-foe Microsoft, but conversely Linux servers from rivals have eaten into Sun's low-end server sales, the company has said.

Loving Linux
Linux is a clone of Unix created by hundreds of open-source programmers, often volunteers, who share programming code without the constraints that keep proprietary the inner workings of software such as IBM's DB2 or Microsoft Windows. For years Sun eschewed Linux, arguing that Solaris was superior, but in February the company reversed course, saying it would release its own version of Linux on servers with Intel or Intel-compatible processors.

Sun's announcement came years after IBM, Dell Computer and Hewlett-Packard embraced Linux, but the company doesn't have as much catching up to do as might appear at first blush. Special-purpose servers from its Cobalt group already run Linux and use Intel-compatible processors. The system interface hides Linux beneath the covers so users don't know it's there.

Supporting Linux on general-purpose servers, though, will mark a major difference in that Sun will have to make sure its entire Sun Open Network Environment (Sun ONE) software collection works on Linux as well as Solaris. Sun also will have to stay on top of bug fixes and make sure Linux systems can be easily managed.

While Sun has agreed with IBM that Linux is worth backing, it disagrees about where it's best used. IBM backs Linux on everything from Intel servers to its top-end mainframes, but Sun advocates its use only on relatively low-end servers with just one or two processors.

Sun's version of Linux is based on the version from Red Hat, Sun executives have said.

Servers based on Intel processors are often hard to tell apart, but blade servers are taking a wide variety of shapes as server makers find different ways to squeeze computers into their enclosures.

While still part of a young market, blade servers already have emerged from HP and start-up RLX Technologies, and are scheduled to debut at IBM and Dell this fall.

Linux and blade servers sit at the low end of Sun's product line. At the high end of the server spectrum, Sun and its competitors have been creating ever more powerful machines, with dozens of processors and hundreds of gigabytes of memory, for strenuous tasks such as governing Ford Motor's manufacturing operation.

At the opposite end of the spectrum, server makers have been creating ever-smaller products for handling jobs such as dishing up Web pages, which requires a large number of small servers rather than a small number of behemoths.

IBM is taking a high-end approach with its BladeCenter products, due by the end of September. Its blades will be as powerful as many stand-alone systems, with dual-processor blades using 2.2GHz Xeon processors and accommodating up to 8GB of memory.

Up to 14 blades will fit in a single enclosure 12.25 inches thick in the IBM system. In coming months HP, which already sells lower-end blades, will release higher-end products that have eight two- or four-processor blades in a 10.5-inch rack.

HP's existing blade servers squeeze 20 into a 5.25-inch enclosure, while pioneer RLX managed 24 in the same size.

Dell and Sun are both aiming for that 5.25-inch thickness, but are otherwise different. Dell's coming PowerEdge 1655mc, expected this fall, will have six two-processor blades, whereas Sun's first products will have a larger number of single-processor blades.

Sun's system also includes a built-in network switch to ease communications among the different blades and to the outside network.