Non-Uniform Memory Architecture
Non-Uniform Memory Access or Non-Uniform Memory Architecture (NUMA) is a computer memory design used in multiprocessors, where the memory access time depends on the memory location relative to a processor. Under ccNUMA, a processor can access its own local memory faster than non-local memory, that is, memory local to another processor or memory shared between processors. NUMA architectures logically follow in scaling from symmetric multiprocessing (SMP) architectures.
ccNuma is Cache Coherent Numa as cache is the rule rather than the exception in general genereal purpose computing the cc is often omitted. Still the cache coherence is one of the major challenges in a good Numa design.
Their commercial development came in work by Burroughs (later Unisys), Convex Computer (later Hewlett-Packard), Silicon Graphics, Sequent Computer Systems, Data General (later EMC) and Digital during the 1990s. Techniques developed by these companies later featured in a variety of Unix-like operating systems, and somewhat in Windows NT.
The NUMA designs used by Convex, Sequent and Data General was developed by the the Numascale team that now has made a modernized design for Hypertransport.