Not long ago Non-Uniform Memory Access (Numa) architecture was being dismissed as a niche technology. But now Microsoft is to introduce support for Numa into future versions of .Net Enterprise Server and .Net Datacenter Server.

Numa is a type of parallel processing architecture in which each processor, or small group of processors, has its own local memory but can also access memory owned by other processors.

Microsoft's move makes sense, because far from being a niche technology pursued by specialist server suppliers, there is every chance that Numa will become one of the dominant memory architectures for servers. Hewlett-Packard's Superdome and just about every other high-end server earmarked for transition to Intel's IA-64 Itanium processors are Numa systems.

What is more, there is a long history of Unix being the chosen operating system to work with Numa, which means that there is now a growing connection between Numa and Linux, Microsoft's most serious rival in the server marketplace.

Getting a grip

Microsoft is keen to strengthen its grip on this market, and will no doubt be heartened by a recent report from analyst company Aberdeen Group on the cost of ownership of Windows 2000 servers for enterprise applications.

Aberdeen Group says that running key back-office applications on Intel servers with Windows is significantly cheaper than Unix systems.

Thomas Manter, research director at the Aberdeen Group, said the cost advantage was larger than anticipated. According to Aberdeen Group, buying and maintaining an Intel-based server running Windows 2000 costs about $1.3m less than a Unix equivalent over a period of three years. For two-way servers, which represent some 75 per cent of the server population, the cost advantage is 70 per cent, because Unix and Risc systems are more expensive and the cost of support staff is much greater. "We did not expect [the cost advantage for Windows[ to be this high," said Manter.

It would be interesting to see a similar analysis comparing Windows 2000 with Linux.

Microsoft said that its move towards Numa architecture is being driven by the release of Intel's Xeon MP server chips, which can be used to build multiprocessor systems. In such systems, Numa can be used to link two or more systems to form a single large server.

Another brick in the wall

Multiprocessor configurations will be increasingly common in servers. But these will not be the single, monolithic systems with which firms are familiar. The trend, with the new Xeon MP processors and, in the longer term, Intel's IA-64, 64bit processor family, is for modular systems, also known as brick servers.

Like blade servers, brick servers will slot into rack systems, but they will be more powerful, with modular elements for specific functionality. And like traditional rack-mounted servers, they will connect into a backplane system. Each manufacturer will have its own design of backplane and this will be a differentiator between them.

The backplane will create a tightly coupled, but readily scalable, multiprocessor system for which Numa-style memory architectures are well suited. John Enck of analyst company Gartner Group said: "In many ways, bricks are the next evolution in Numa technology."

Brick servers are not expected to be widely available much before the end of this year, with either IBM or Compaq expected to lead the way.

The new brick servers, especially those based on IA-64 processors, could be a good bet for the high end, and could threaten the dominance of Unix and Risc systems in the long term. With Numa likely to be a key component in such systems, Microsoft's move is necessary if it is to stand a chance in this market.

BRICK SERVERS SCALE UP

• Microsoft is to introduce support for Numa memory technology into future versions of .Net Enterprise Server and .Net Datacenter Server.
• Microsoft said its move is being driven by the release of Intel's Xeon MP server chips, which can be used to build multiprocessor systems.
• Numa architecture is well suited to the emerging class of modular, multiprocessor brick servers.