Do I need a retimer? CSE847 / SAS3-826-EL1-N4 / PCI Gen3 U2

[whoknew123]

I need someone to save me from going down a never ending rabbit hole here.

I have a CSE847 case and plan to get a BPN-SAS3-826-EL1-N4 for some Gen3 U2 drives. Motherboard is romed8d-2T. Will I need a retimer card or will a passive x16 to 4x U2 card(with bifurcation enabled) work?

 

[i386]

For pcie 3.0 passive adapters (+ short cables, like within a standard server chassis) should be fine, for pcie 4.0 and newer it will depend on cable & connector quality and cable length

 

[NablaSquaredG]

ill I need a retimer card or will a passive x16 to 4x U2 card(with bifurcation enabled) work?

Redrivers also exist (they are in between "passive" and "retimer"), e.g. Supermicro AOC-SLG3-4E4R

It's difficult to say, really depends on your cables, quality of your passive breakout card and whether the board has any redrivers or not.

 

[whoknew123]

Redrivers also exist (they are in between "passive" and "retimer"), e.g. Supermicro AOC-SLG3-4E4R

It's difficult to say, really depends on your cables, quality of your passive breakout card and whether the board has any redrivers or not.

Are there any "good" brands of passive cards? The only one from a familiar brand I've found is 10gteck.

From the reading I've done, not a ton, it seems the general sentiment is that redrivers often come with a host of random issues if passive cards didn't work. Kind of felt like either passive works or you're better off going straight to a retimer. Again, that's my takeaway after a couple hours of reading, so by no means an educated opinion.

 

[NablaSquaredG]

Kind of felt like either passive works or you're better off going straight to a retimer. Again, that's my takeaway after a couple hours of reading, so by no means an educated opinion.

I have some machines with this exact backplane, BPN-SAS3-826-EL1-N4, and the Supermicro redrivers work like a charm.

For Gen3, I found redrivers to be generally sufficient. For Gen4, I prefer retimers.

 

[whoknew123]

I have some machines with this exact backplane, BPN-SAS3-826-EL1-N4, and the Supermicro redrivers work like a charm.

For Gen3, I found redrivers to be generally sufficient. For Gen4, I prefer retimers.

Ah, perfect then. These cards Do Not use a proprietary pin out right? As in, I can use any brand mini sas hd to mini sas hd cable?

And are you running any of them on 3rd party/non SM boards?

 

[mattventura]

You should first use the two OCuLink ports on the motherboard before moving onto a card.

Supermicro and ASRock both seem to have a slightly non-standard (pre-standardization?) OCuLink pinout, but they supposedly have the same non-standard pinout, so the appropriate supermicro cable should work.

 

[whoknew123]

You should first use the two OCuLink ports on the motherboard before moving onto a card.

Supermicro and ASRock both seem to have a slightly non-standard (pre-standardization?) OCuLink pinout, but they supposedly have the same non-standard pinout, so the appropriate supermicro cable should work.

I’ve got 3 gen3 drives. Feels like a waste to put them on gen4 ports when I’d have to figure something out for the 3rd either way. I’d rather put these 3 of a card of some sort than have to re do things later when gen4 prices come down.

 

[UhClem]

For pcie 3.0 passive adapters (+ short cables, like within a standard server chassis) should be fine ...

I agree, but doubt that "short cables" (ie ~50cm) is even required.
See here [Link] for a perfectly functioning signal "quagmire".