New Generation of Hardware Needed for DataCenter To Scale Beyond Eight CPUs

A new generation of Intel-based systems that combine the benefits of both the mainframe and PC server worlds is making its appearance this year. These systems promise to offer the high degree of reliability, availability, and scalability previously available only on mainframe-class systems, yet offer the open architecture, standard components, rapid evolution, and lower cost of the PC server world. This will give OEMs significant opportunities for differentiation, as they move away from Intel’s ProFusion architecture and develop their own methods of balancing memory, processors, cache, and input-output (I/O) to allow their large systems to efficiently scale up to 32 or more processors.

As the number of processors grows beyond four, bus contention between the CPUs and main memory limits the ability of a system to linearly increase its processing power. Intel’s ProFusion architecture increased this limit to eight, but beyond that a different approach is necessary. Some large system vendors, such as IBM’s Sequent division, abandoned the symmetrical approach and adopted a Non-Uniform Memory Access (NUMA) architecture. NUMA uses pods of 4-CPU modules, each with its own memory, all connected via a Scalable Coherent Interconnect (SCI). Unfortunately, this architecture requires extensive changes to the operating system to account for variability in the location and response time of system memory.