Itanium 2 will change the way servers access memory, enabling a new class of low-cost, modular designs.

Until now, Windows software would only work on multiprocessor servers built to the symmetric multiprocessing (SMP) model. This provides equal access to memory for all processors. SMP is relatively simple to implement but imposes restrictions on the number of chips fitted. Given that all chips share the same bus to memory, every time one is added, the memory bandwidth available to each is reduced. The alternative is a non-uniform memory access (Numa) model, where chips have high-speed access to their own local RAM, and slower access to the RAM that is local to the other processors.

Numa has an important benefit. Servers can be scaled up by adding new processors and their associated RAM, and linking these blocks to the existing server using a lower-speed interface. IBM was first to market with this design, used in its x440 server.

Vendors such as Dell are expected to market modular, brick-format Itanium 2 servers that can be used as standalone systems, or linked together to form larger Numa systems.

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