Seems these can picked up fairly cheap these days on eBay.
Looking at picking up a new motherboard that supports up to 2TB of Optane DIMMs and I was wondering what kind of support Scale has for this. Will it just be seen as standard DRAM for ARC?
Does it support app direct mode where I could use the NVDIMMs as an sVDEV or L2Arc?
Support should be down to what the motherboard can expose; to ZFS, it would be just RAM and/or another NVMe drive.
I remember I saw a comment that Optane DCPMM were not so great SLOG as one would hope.
As for L2ARC, one would have to consider how many tier levels make sense. RAM is tier 1; L2ARC is an optional Tier 2. DCPMM in memory mode would be Tier 1.5, with the real RAM being Tier 1—but ZFS would not know which is what, when “ARC” is actually in RAM and when it is fast-but-slower-than-RAM Optane DCPMM. My gut feeling is that DCPMM would be best used in memory mode to provide a HUGE ARC without any L2ARC.
If you’re using Optane DIMMs in Memory Mode, they will appear as standard DRAM, and ARC will benefit by having more memory for caching. However, in App Direct Mode, you can use them for ZFS features like L2ARC or sVDEV but only if your system allows direct configuration of ZFS. Platforms like Scale Computing HC3 may not expose that level of control, so App Direct use for things like L2ARC might not be supported out of the box.
WOuld a PC boot from such a drive?
