[rachelbythebay]

If you're allowed to call a multi-node setup a "supercomputer", then how about 3 40 machine racks of Xeons where each one is dual-socketed, has 12 DIMMs per socket, and is using 128 GB DIMMs?

3 racks * 40 boxes * 2 sockets * 12 DIMMs per socket * 128 GB = 368640 GB or 360 TB raw. Remove some of that for overhead (kernel, OS gunk, network buffers, whatever code you'd have to run to make it into a cluster), and there's your 256 TB with a bunch left over.

Stuff like this is why I sometimes say that a lot of these startups could be done with "three Xeon racks" if they actually cared about doing it right.

[Note: assumes 2nd generation Xeons (Skylakes), with 24 DIMMs. Ice Lake = more/bigger memory, fewer actual machines.]