Once upon a time I hacked on the AIX kernel which ran on POWER hardware (I think they're up to POWER8 or higher now). In my time there the latest hardware was P

Once upon a time I hacked on the AIX kernel which ran on POWER hardware (I think they're up to POWER8 or higher now). In my time there the latest hardware was POWER7-based. It maxed out at 48 cores (with 4-way hyperthreading giving you 192 logical cores) and a max of I think 32TB RAM. Not the same hardware as mentioned in the OP, but pretty big scale nonetheless. This shows a logical diagram of how they cobble all these cores together: http://www.redbooks.ibm.com/abstracts/tips0972.html?Open http://www.redbooks.ibm.com/abstracts/tips0972.html?Open I've seen these both opened up and racked up. They are basically split into max 4 rackmount systems, each I think was 2U IIRC. The 4 systems (max configuration) are connected together by a big fat cable, which is the interconnect between nodes in the Redbook I've linked above. The RAM was split 4 ways among the nodes, and NUMA really matters in these systems, since memory local to your nodes is much faster to access than memory across the interconnect. This is what I observed about 5-6 years ago. I'm sure things have miniaturized further since then...