The 6240 has a 1TB memory cap (sum Optane+DRAM). You’ll want an “L” suffix SKU. A 6268CL or 8275CL will perform much better, and support 4.5TB of memory per socket.
Optane requires BIOS support, in addition to CPU support. It is not “plug-and-play” as such, and must be configured in the BIOS in one of the available addressing modes (memory mode, app direct, etc.).
I’d recommend checking your motherboard’s manual to make sure it has a DCPMM configuration utility built in. Nobody seems to know if the SAGE boards had DCPMM support, and ASUS doesn’t list it anywhere on their support page.
I ran 2TB of Optane DCPMM in my workstation for about a year before shelving the sticks and replacing it with DRAM.
In memory mode, hitting Optane (that is to say, when the dataset would not fit in the DRAM cache) increased my LLC miss latency from 150ns with DRAM only, to well over 3000ns. Whether that’s performant in your use case will obviously vary.
Official documentation recommends a 1:8 configuration of DRAM to Optane. I had much better performance running 1:4. In any case, it’s best used in a 2DPC configuration with 1 DRAM and 1 DCPMM per channel.
No, but you wouldn’t want to. DCPMM has to be interleaved by the IMC to be performant. Sequential read bandwidth is less than 8GB/s per stick. The more channels (up to 6) being interleaved, the better.
With current Fedora-based Linux distributions, you can partition your DCPMMs in app direct mode like any other disk. But the DIMMs are interleaved by the BIOS, and aren’t partitioned along hardware boundaries.
Debian-based distros, in my experience, lack the required NVDIMM driver OOTB.