SGI gives Linux a helping hand

Tomorrow at Linux Expo in North Carolina, SGI will announce that it will freely license its XFS "journaling" file system technology, a core component of its Irix operating system, as open source software. Effectively, this means developers will be able to incorporate XFS into their own variants of Linux.

For SGI, the move is intended to promote affinities between the Linux community and its own products. "People will be able to take advantage of the unique capabilities on SGI hardware," said Dave McAllister, SGI's strategic technologist.

Going further, Tony Iams, an analyst at D.H. Brown, said releasing XFS as open source will allow SGI to become the hardware of choice for Linux-Intel systems. "It opens up opportunities for them, given their strategic dependence" on Linux, he said.

Linux currently lacks a journaling file system, a feature that makes it easier to get a Unix computer up and running after a system crashes. Although several people are at work on such a component, including programmer Stephen Tweedie at Linux seller Red Hat, its absence remains a weakness when it comes to using Linux at the high end, according to the D.H. Brown firm.

Numerous hardware and software companies are taking steps to support Linux, a Unix-like operating system that can be obtained for free, but SGI's effort goes farther than most, Iams said. "On balance, it's a rational decision for them," he said.

Without a journaling file system, rebooting a computer after a crash can be extremely time-consuming, a critical issue as companies look for computer systems that are available to users around the clock. That's particularly true of companies who base their business operations on computer systems, what the industry calls mission critical computing.

While SGI's announcement will come tomorrow, the software itself won't be available for download until the summer. SGI still is deciding how to structure the open source license, the company said, though it is sure to meet the requirements of the Open Source Definition, a spokesman said.

All major Unix flavors as well as Windows NT already have a journaling file system, Iams noted. The lack of one in Linux was one of its three chief weaknesses, he said, and SGI's release of XFS likely will speed its development.

XFS has many advanced features, but SGI isn't releasing all of them as open source, Iams added. The open source version--which anyone will be able to see, modify, and distribute--is limited to 64-bit file support and the journaling system.

Although SGI plans to release the software, that doesn't guarantee XFS will be adopted into Linux, cautioned Giga Information Group analyst Stacey Quandt. "That's really up to Linus [Torvalds, Linux leader] and the others," she said.

In addition, the open source community will pay careful attention to the exact terms under which SGI licenses XFS, she said.

McAllister said SGI has talked to open source journaling file system developers, and "most of them have been pretty enthused."

XFS is based on B-tree sorting method, a technique for finding files that's faster than the linear sorting method used in many file systems, McAllister said.

With the 64-bit file system in XFS, computers can manage files as large as 9 million terabytes and file systems of 18 million terabytes, McAllister said. Linux can't currently deal with files that large, he said. "We expect the technology is a little in front of the demand," he said, but already there are scientific users who nave data sets that large.

That need for large file system access will become stronger with the effort to get Linux able to take full advantage of 64-bit chips such as Sun's UltraSparc, Compaq's Alpha, Hewlett-Packard's PA-RISC, or Intel's upcoming Merced.