Using clusters of relatively inexpensive Intel-based servers to handle high-performance computing workloads has taken off in the past couple of years among researchers and academics. That poses a challenge for Stratus Technologies Inc., which is working to position its Windows-based fault-tolerant servers as a competitive alternative. The company Monday will add to its fault-tolerant lineup two servers that will ship with Windows Server 2003 Enterprise Edition.

Stratus' midrange ft5600 and enterprise-class ft6600 are smaller and about half the price of the company's earlier line of fault-tolerant servers. Combined with the entry-level ft3300, which also ships with Windows Server 2003 Enterprise Edition, the servers range in price from $20,000 to $100,000.

"Stratus is competing with companies that sell clustering technology," says Denny Lane, director of product marketing, "Unlike them, we don't have failover or recovery processes because we don't need them."

Fault-tolerant servers are designed to run operations in parallel to protect a company against downtime, in the event one set of operations fails because of hardware or software problems. This was an expensive proposition when Stratus' servers ran either its VOS Unix-derivative operating system or HP-UX. Concerned about the lack of growth in the Unix market, the company decided several years ago to build high-availability servers on Intel processors and Windows.

This move has helped the company compete against server clusters that are replacing supercomputers in high-performance computing situations. "Clustered systems need a degree of scripting and testing, then rescripting and retesting as the cluster grows," Stratus CEO David Laurello says. Although fault-tolerant servers can't compete with clusters in terms of scalability, Laurello says his company takes the crown when it comes to high availability.