[Beowulf] Tiered RAM

[John Hearns]

Over on the SLURM list we recently had a very good discussion on swap
space and job suspension. I commented that for large memory systems we
should be seeing tiered RAM devices by now.


I had a look at the Intel pages on Optane memory. It is definitely
being positioned as a fast file cache, ie for block
oriented devices.
https://www.intel.com/content/www/us/en/architecture-and-technology/intel-optane-technology.html

I mentioned Diablo Technologies, who I think have gone out of
business. They had available a DRAM form-factor high capacity memory
device using flash. This worked by tiering RAM memory - ie a driver in the Linux
kernel would move little used pages to the slower but higher capacity
device.
I though the same thing would apply to Optane, but it seems not.
Can anyone comment? I do not expect anyone under NDA to comment of course.

I have probably said this on many forums - we are seeing the trend to
wards higher and higher memory systems, which enable more detailed
meshes, bigger models and in-memory databases. But do we need huge
amounts of expensive and fast DRAM to do this?