Mux needed for AOC-SLG3-4E4R / AOC-SLG3-2E4R?

[lunadesign]

I'm interested in building a storage server and using a few AOC-SLG3-4E4R / AOC-SLG3-2E4R cards to connect to a bunch of NVMe drives.

Per this Supermicro page, AOC-SLG3-4E4R, AOC-SLG3-2E4R (and all the other cards without a PCIe switch) require a mux for more than one card on same PCIe bus.

Can someone please explain:
1) Why is a mux needed?
2) What sort of mux product would I need to obtain?
3) How much would a mux impact performance?

Thanks!

 

[BlueFox]

1. You are connecting multiple PCIe devices to the same slot.
2. Your motherboard needs to support PCIe bifurcation. You cannot get one separately.
3. No noticeable impact.

If your motherboard doesn't support PCIe bifurcation, you will need to get one of the cards with a switch.

 

[lunadesign]

1. You are connecting multiple PCIe devices to the same slot.
2. Your motherboard needs to support PCIe bifurcation. You cannot get one separately.
3. No noticeable impact.

If your motherboard doesn't support PCIe bifurcation, you will need to get one of the cards with a switch.

I might be reading this wrong, but are you saying that the mobo bifurcation support *is* the required mux?

FWIW, the Supermicro page says "Needs MUX for more than one card on same PCIe bus". Note that it says "more than one card" not "more than one drive".

 

[lunadesign]

Anyone else have any thoughts on this? I'm guessing *someone* has tried using multiple non-switch cards on the same motherboard to ruh more than 4 NVMe drives....

 

[TrumanHW]

Anyone else have any thoughts on this? I'm guessing *someone* has tried using multiple non-switch cards on the same motherboard to ruh more than 4 NVMe drives....

I agree with you!
I was doing very similar research...perhaps you actually have a SuperMicro MB..? Or server..?

One thing to remember about most mfrs; They speak changlish as a 2nd language. Don't be surprised if it's an error.

I'm researching the SSD7120 (forFreeNAS) & was sugg. to use AOC-SLG3-4E4R which led me to consider AOC-SLG3-4E4T & similar HBAs.

Some SuperMicro's HBAs explicitly state:This product does not work with 3rd party servers. It can only work with validated Supermicro server systems and Supermicro motherboards. Please refer to the validated platforms list.

They difference between the AOC-SLG3-4E4R and AOC-SLG3-4E4T ... based on the below definition, RETIMER sounds superior.
• 4E4R uses a - 'redriver' ... (Whether it's the reason for the naming convention or code or not)
• 4E4R uses a - 'retimer' ... not...that they explain the difference! lol.

RETIMER vs REDRIVER:
A retimer is a mixed analog/digital signal, protocol-aware-device able to fully recover data, extract the embedded clock & retransmit a fresh copy of the data with a clean clock. In contrast, a redriver amplifies a signal, whereas a retimer retransmits a fresh copy of the signal.


Do you have a 4E4R already..? Do you use it with a SuperMicro MB or 3rd party MB..? Have you EVER used it with a 3rd party MB..?

SuperMicro's HBA Product Matrix

Are you trying to use 2x HBAs for more than 4x NVMe devices (presumably, x4 lanes each)..? If so, how did you use the first 4 drives..?
What OS are you using it with..? (My goal is FreeNAS // Open ZFS) ... which SSD drives have you used..?
If you don't have a SM MB ... does the board you have not have bifurcation..? Or are you just clarifying..?
How many drives and which model // capacity SSDs..?

May I inquire as to your performance results (if it's not too inconvenient)

Did you consider other options, like the SSD7120 from HighPoint..?

Thanks!