Redmond's move reinforces the chip's position as a component mainly meant for powerful multiprocessor servers.
Intel in recent years has positioned Itanium chiefly as a processor for powerful multiprocessor servers, a prestigious market, but one much smaller than originally envisioned. Microsoft's move essentially reinforces this big-iron positioning.
"Longhorn Server for Itanium won't run all workloads," a Microsoft representative said in a statement.
The operating system is designed for three specific types of higher-end tasks: databases, custom jobs and line-of-business applications such as accounting and customer relationship mananagment, or CRM. Among the tasks it won't be able to handle are "fax server, Windows Media Services, Windows SharePoint Services, file and print servers, and others," Microsoft said in a bulletin.
Microsoft's move is the latest illustration of the less-ambitious role projected for Itanium. The processor family's debut was marred by delays, poor performance and software incompatibility with servers using x86 processors such as Intel's Xeon and Advanced Micro Devices' Opteron. Many of those initial problems are now fixed, but in the meantime, x86 servers grew more powerful, and IBM ceased developing its own Itanium server. Itanium allies haven't given up and are still working on Itanium market development projects.
The narrower role for Longhorn on Itanium dovetails with Microsoft's plans for an earlier server operating system, Windows Server 2003 R2, which is due out at the end of this year and won't be available for Itanium.
The features coming with R2 are geared chiefly for tasks run by lower-end servers, Microsoft argues. Those features focus on identity and access management, branch office servers, and storage system setup and management.
Novell's Suse Linux Enterprise Server and Red Hat Enterprise Linux also run on Itanium. And Hewlett-Packard, which began the development of Itanium and cooperated for years with Intel on the chip, offers its HP-UX version of Unix for Itanium, as well as its OpenVMS and NonStop operating systems.