Need recommendations for PCIE NVMe Adapter

[Kailee71]

Hi all,

i'm seeing more and more sync writes on my truenas server and so am planning to try out using a couple of 32Gb Optane M10 M.2 NVMe ssds (MEMPEK1J032GA) in my DL380p and/or Dl560 (both Gen8) als SLOG devs and/or boot volumes. As a test I've temporarily used a standard SATA ssd on the internal 2Gb P420i (yes, with battery backup) to see if performance would benefit, and it made a real difference. So as I'm not totally confident using the onboard RAID (even if "only" as a battery backup slog dev) I'm willing to spend a few euro on testing with the small 32Gb 3D Xpoint NVMe ssds on PCIe adapters. Ideally, I'd use a dual adapter with 2 32Gb M.2 Optanes, one to boot from, one as an slog, but if these don't exist I'll happily just get a single for the slog dev.

Can anybody recommend which PCIe adapters are compatible with the drives I'm looking at? I'm guessing the 32Gb optanes are true NVMe, and not NGFF of even SATA, but I'm unsure how to actually tell which adapters will work for these - I'm confused by the different keys and which ones signify which interfaces actually in use.

Any pointers much appreciated!

TIA

Kai.

 

[jgreco]

You won't be able to boot from an NVMe device unless that is supported by your system's BIOS.

You can use pretty much any $5 single M.2 NVMe adapter, easily found on eBay, for a single device. Quality varies.

In order to use the inexpensive dual M.2 NVMe adapters, you need a board that supports PCIe bifurcation. A good (but expensive) one is

Supermicro AOC-SLG3-2M2

There are MUCH cheaper variations on this out there, eBay has cheapies for like $15. These are basically just boards with power regulators and directly attach the SSD's to the PCIe lanes. This means that two PCIe devices show up in a single slot, so PCIe bifurcation support is needed for the second one to show up and work. A dual card like this will let a single NVMe device work in a non-bifurcation mainboard though.

Supermicro AOC-SHG3-4M2P

A card like this, on the other hand, has a built-in PLX switch and does not require bifurcation support. This is the correct way to add multiple NVMe M.2 drives in a single slot on a non-bifurcation board.

 

[Kailee71]

Hi jgreco and *many* thanks for the (as usual from you) detailed info. I found very little on whether gen8's support bifurcation but from what I did find it doesn't seem they do. So I think I'll stick with 1x m-key 1x b-key dual card, something like this; I'll use an old 860evo to boot from (SATA M.2, connected via cable to host) and then the second slot holds the slog optane. I'll report back with results when I receive the adapter.

Cheers,

Kai.

 

[jgreco]

In my experience the SilverStone stuff is very nice although perhaps a bit overpriced. As discussed elsewhere, I've been using their SDP11's for refurb work and am quite pleased with them.