Hi everyone, I am not so active here, I apologize, however I am a very regular viewer of the YouTube show.
I am currently wanting to build a no-compromise Home NAS from Quasi-Enterprise Grade Stuff. I have the ASRockRack EPYC3251D4I-2T mainboard (https://www.asrockrack.com/general/productdetail.asp?Model=EPYC3251D4I-2T#Specifications) and want to connect to it:
6x SATA HDD (4x SATA on OCULink 4x Header, 2x SATA on SATA Headers)
5x M.2 SSD (4x PCI-Express x4 from two OCULink x8 Headers, 1xM.2 on-board)
I am currently having a problem connecting up the M.2 SSDs to the OCULink Headers and I am not sure why. I am using the following cables/doodads:
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OCULink x8 connector to dual-U.2 SFF-8639 connectors (https://www.ebay.de/itm/115632152878). This should allow connecting two U.2 SSDs to a single OCULink x8 header on the mainboard. From what I can measure with my multimeter, this cable pretty much conforms to SFF-9402 (page 21, SFF-8621 and SFF-8639 columns, here: https://members.snia.org/document/dl/27380). Although it seems that pins such as CPRSNT[A|B] don’t seem to be connected to anything?
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ICY BOX U.2 to M.2 adapter in 2.5" form factor. Accepts the U.2 cable and takes a M.2 drive. (https://www.amazon.de/dp/B08M3WT4WL?psc=1&ref=ppx_yo2ov_dt_b_product_details). I have tested this adapter with other cables (such as a M.2 → U.2 pigtail) and it works as expected.
Now the issue is, that no matter what I do, my 4 U.2 (M.2) drives don’t get detected by the UEFI or the Linux Kernel. I have already configured the bios such that the OCULink x8 Headers are in x4x4 Mode and PCIE (not SATA).
The issue has to be the OCULink to U.2 cable in my opinion, but lacking experience with Enterprise stuff, I am unsure where to start looking. In the SFF-9402 spec, this adapter cable is missing a lot of sideband pins on the SFF-8639 (U.2) side, which are present on the OCULink side. E.g.: Two-Wire (SMBUS), CPRSNT[A|B], BP_TYPE[A|B]. Are they not needed? I suspect the PCI-Express Host will require at least some of these pins to have a definite state, if they are not connected through to the SFF-8639 header.
Could this be my problem? How would it be possible to connect the M.2 drives to my OCULink x8 headers?
Thanks a bunch in advance, guys for any pointer you can give me!
EDIT: I can open the OCULink Connector (the other one is overmolded…). Does it make sense to try pulling CPRSNT low permanently?
