Stratus will ship the 64-bit version of Linux with its hardware beginning in early August. This Linux offering doesn't change hardware pricing on the Stratus ftServer models that now only run Windows Server 2003, said Denny Lane, director of product marketing at the Maynard, Mass.-based vendor.

Linux isn't entirely new to Stratus. The company has been making an embedded version of the operating system, built on Version 2.4 of the Linux kernel, available to some customers for specific uses, such as power-generation control. Lane said this version has been heavily customized by Stratus to work in a fault-tolerant environment and isn't ready for broader use.

Lane said the company believes the newer 2.6 kernel is ready for a fault-tolerant environment, and said Stratus has only had to make a "modest amount of changes around the edges" of the Linux kernel to prepare it for its servers.

Gordon Haff, an analyst at Illuminata Inc. in Nashua, N.H., said Linux on Stratus may be seen as a substitute by users who rely on Unix clusters to achieve high availability.

"What a lot of people have found over the years is that the complexity of clustering often acts against clustering delivering higher availability in practice, said Haff.