The group I'm in at NASA Goddard has two UV300s. They have 96 cores each (no hyperthreading) and 6TB of RAM. And they are loud.

The SGI Altix line, which used Itanium 2, could go up to 1024 cores with a single system image, which is just insane. We had one of those at Goddard a decade or so ago, but I didn't have access to it.

I'm fairly sure UV (or some SGI labelling) has gone up to 1024-ish cores in a single system image, but I don't have a reference. (SGI Origin 3000 was spec'ed to 512 cores long ago.)

1536 cores on Cambridge’s COSMOS SGI Altix UV2000 system:

http://www.cosmos.damtp.cam.ac.uk

Speaking of SGI, I was expecting the Cray XC family to be able to do that with the ludicrously fast interconnects they have, but I couldn't find any mention of it.

No, an XC40 runs a kernel on each node, the programming model is MPI, not SSI with NUMA. It runs a minimalist Linux distro called CLE. The nodes are surprisingly small, in terms of memory too, 64 or 128G. Physically they are beautiful to look at, so clean, just a CPU and some memory and nothing extraneous. Cray really should do glass cases.

They used to make beautiful computers.

The salient hardware difference is probably cache coherence in the SGI interconnect.

No, the Ares interconnect is brutally fast but it fundamentally isn’t doing anything as complicated as that. It acts as both storage and networking between the nodes.

I missed this at the time, but yes -- that's the point, in comparison with NUMAlink or whatever it is now. (s/Ares/Aries/)