Quad Port U.2 card?

Hetz Ben Hamo

New Member
May 16, 2019
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Hi,

I'm sure I'm not the only who is looking for such a solution: I'm looking to purchase 4 U.2 drives and hook them into a Threadripper based motherboard (I didn't buy any motherboard yet, still planning).

Surprisingly, the only card I found is the Supermicro AOC-SLG3-4E4R (and the 4E4T variant) and I cannot find any information if this card will work on any non Supermicro board.

Does anyone know any alternative card? I can find tons of Quad M.2 PCIe cards, but almost-none with a U.2 version. I can buy a quad M.2 and connect 4 M.2 to U.2 converters, but it's a very ugly hack.

Thanks
 

JoshDi

Active Member
Jun 13, 2019
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Look at the 4 port Oculink card (AOC-SLG3-4E4T) or 8 port Oculink card (AOC-SLG3-8E2P), both from Supermicro. You need to use the CBL-SAST-0956 cables from Supermicro to use them with U.2 drives. I currently use the AOC-SLG3-8E2P with 4 Intel DC 3520 1.2tb drives and get full 16x speed. The AOC-SLG3-4E4T requires pcie bifurcation and the AOC-SLG3-8E2P is a HBA so just needs a 16x pcie slot.
 

UhClem

Member
Jun 26, 2012
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Look at the 4 port Oculink card (AOC-SLG3-4E4T) or 8 port Oculink card (AOC-SLG3-8E2P), both from Supermicro. ... The AOC-SLG3-4E4T requires pcie bifurcation ...
I think both are excellent suggestions (especially the 8E2P). I'm pretty sure that the AOC-SLG3-4E4T does NOT require bifurcation--that large heatsink is most likely covering a PMC-Sierra/Microsemi/Microchip fanout switch, probably the PM8532 (configured as x16-in, 4_by_x4-out) [part of their Switchtec PFX family http://ww1.microchip.com/downloads/en/DeviceDoc/00002849A.pdf]

[Speculating further ... I think that] Your AOC-SLG3-8E2P probably uses a PMCetc storage switch, probably the PM8543 (configured as x16-in, 8_by_x4-out) [part of their Switchtec PSX family https://www.microsemi.com/document-...chtec-psx-storage-switch-family-product-brief].

It is very nice to see that greedy Broadcom/Avago (they acquired PLX) has some (formidable, I hope) competition in the PCIe switch business. [(wild) speculation:] I expect this functionality to be flexibly integrated into workstation-class motherboards in a few years.

Please note: I know NOTHING. I retired 20+ years ago.
 

JoshDi

Active Member
Jun 13, 2019
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I think both are excellent suggestions (especially the 8E2P). I'm pretty sure that the AOC-SLG3-4E4T does NOT require bifurcation--that large heatsink is most likely covering a PMC-Sierra/Microsemi/Microchip fanout switch, probably the PM8532 (configured as x16-in, 4_by_x4-out) [part of their Switchtec PFX family http://ww1.microchip.com/downloads/en/DeviceDoc/00002849A.pdf]

[Speculating further ... I think that] Your AOC-SLG3-8E2P probably uses a PMCetc storage switch, probably the PM8543 (configured as x16-in, 8_by_x4-out) [part of their Switchtec PSX family https://www.microsemi.com/document-...chtec-psx-storage-switch-family-product-brief].

It is very nice to see that greedy Broadcom/Avago (they acquired PLX) has some (formidable, I hope) competition in the PCIe switch business. [(wild) speculation:] I expect this functionality to be flexibly integrated into workstation-class motherboards in a few years.

Please note: I know NOTHING. I retired 20+ years ago.
The AOC-SLG3-4E4T definently requires bifurcation.

Please check this post: https://forums.servethehome.com/ind...aoc-slg3-4e4r-on-x10drh-ct.24600/#post-231280
 
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UhClem

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Jun 26, 2012
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The AOC-SLG3-4E4T definently requires bifurcation. ...
Thanks for the correction on the 4E4T.
I'd really like to see a comprehensive test/review of a fully-populated 8E2P--any pointers?

--"If you push something hard enough, it will fall over." - Fud's First Law
 

JoshDi

Active Member
Jun 13, 2019
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I have that card. The 8x oculink cables will run as a total of 16x pcie3
 

zir_blazer

Active Member
Dec 5, 2016
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Look at the 4 port Oculink card (AOC-SLG3-4E4T) or 8 port Oculink card (AOC-SLG3-8E2P), both from Supermicro. You need to use the CBL-SAST-0956 cables from Supermicro to use them with U.2 drives. I currently use the AOC-SLG3-8E2P with 4 Intel DC 3520 1.2tb drives and get full 16x speed. The AOC-SLG3-4E4T requires pcie bifurcation and the AOC-SLG3-8E2P is a HBA so just needs a 16x pcie slot.
Not very reelevant, but I was checking out of curiosity the AOC-SLG3-4E4T Manual and found out that it uses PCI Express SMBus. For those that don't know, PCI Express Slots have two Pins reserved for an optional SMBus, which in many consumer Motherboard is not implemented (Nor mentioned at all). I noticed that several Supermicro Motherboards (Including my X10SAT) have some Jumpers to enable/disable a PCIe Slot SMBus pins, but I never hear about a card that actually used it, not for what.
Then, the question would be: Since this card uses PCIe SMBus, does it REQUIRES working PCIe SMBus support in order to work, or not? Also note that even if a Motherboard supports the optional PCIe SMBus, it may not do so in all PCIe Slots.
 

JoshDi

Active Member
Jun 13, 2019
177
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Not very reelevant, but I was checking out of curiosity the AOC-SLG3-4E4T Manual and found out that it uses PCI Express SMBus. For those that don't know, PCI Express Slots have two Pins reserved for an optional SMBus, which in many consumer Motherboard is not implemented (Nor mentioned at all). I noticed that several Supermicro Motherboards (Including my X10SAT) have some Jumpers to enable/disable a PCIe Slot SMBus pins, but I never hear about a card that actually used it, not for what.
Then, the question would be: Since this card uses PCIe SMBus, does it REQUIRES working PCIe SMBus support in order to work, or not? Also note that even if a Motherboard supports the optional PCIe SMBus, it may not do so in all PCIe Slots.
The AOC-SLG3-4E4T card comes with the SMBus cable to connect to Supermicro motherboards. From the sounds of the user manual, it is optional. I believe if it is not connected, hotswapping of U.2 drives will not be supported.
 

zir_blazer

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Dec 5, 2016
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The AOC-SLG3-4E4T card comes with the SMBus cable to connect to Supermicro motherboards. From the sounds of the user manual, it is optional. I believe if it is not connected, hotswapping of U.2 drives will not be supported.
Supermicro FAQ mentions lack of hotswapping support if that cable is not plugged. However, I have absolutely no idea why they would use a separate cable for SMBus when the PCIe Slots themselves already provides optional Pins for it (B5 SMCLK and B6 SMDAT). It would make more sense if that cable was used to connect the card to a backplane, not the Motherboard itself, as I think that OCuLink 3and U.2 have no Pins reserved for a sideband Bus so an auxiliary cable would be useful in that case (OCuLink actually has a pair of "2-WIRE CLOCK" and "2-WIRE DATA" pins according to the specification, so maybe it can do I2C/SMBus).
I did found mentions about the cable being used to connect the card to the Motherboard, but given what I mentioned about PCIe Slots, sounds stupid. I would love to understand what is going on behind some design decisions...
 
Last edited:

ipreferpie

Member
May 27, 2018
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Hi,

I was wondering if anyone has insights on solving my NVMe drives appearing sporadically after reboots on ESXi. Here's my config:

HBA: SM AOC-SLG3-4E4T
MB: X11DPH-T
Backplane: SM BPN-SAS3-846-8N
SSD: Intel D4502 U.2 7.68TB & Optane 905P U.2 960GB
Host: ESXi 6.7U3

I have 2 D4502 SSDs that are experiencing constant drop outs after reboots. I takes around 10x tries to even have 2 show up on ESXi since usually one one or none show up after rebooting. On the other hand the both Optane SSDs have no problem showing back up consistently. Does any one have similar experiences? I already ruled out thermal throttling since they're in the 35-45C range. Much appreciated!