However, SMP systems suffer disadvantages in that system bandwidth and scalability are limited. Although multiprocessor systems may be capable of executing many millions of instructions per second, the shared memory resources and the system bus connecting the multiprocessors to the memory presents a bottleneck as complex processing loads are spread among more processors, each needing access to the global memory. As the complexity of software running on SMP's increases, resulting in a need for more processors in a system to perform complex tasks or portions thereof, the demand for memory access increases accordingly. Thus more processors does not necessarily translate into faster processing, i.e. typical SMP systems are not scalable. That is, processing performance actually decreases at some point as more processors are added to the system to process more complex tasks. The decrease in performance is due to the bottleneck created by the increased number of processors needing access to the memory and the transport mechanism, e.g. bus, to and from memory.

Alternative architectures are known which seek to relieve the bandwidth bottleneck. Computer architectures based on Cache Coherent Non-Uniform Memory Access (CCNUMA) are known in the art as an extension of SMP that supplants SMP's "shared memory architecture." CCNUMA architectures are typically characterized as having distributed global memory.