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Parzival

macrumors regular
Original poster
May 12, 2013
154
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I need a lot of disks, and want them to be seperated as much as possible.

My question is, can all (or most) of the PCIe slots be used for this purpose?

I would be using cheap M.2 SSD to PCIe adapter cards.
 
Theoretically, yes. You might hit a limit at some point with total number being 6 available slots with GPU and I/O card in slot 8.

You might get better speed from something like Highpoint or Sonnet M.2 adapters, however.
 
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Theoretically, yes. You might hit a limit at some point with total number being 6 available slots with GPU and I/O card in slot 8.

You might get better speed from something like Highpoint or Sonnet M.2 adapters, however.

Thanks for your reply!

Would a card like the ASUS Hyper M.2 X16 Card V2 be a good choice as well? It's a lot cheaper than the Sonnet adapter:
https://www.asus.com/Motherboard-Accessories/HYPER-M-2-X16-CARD-V2/

Also, do you happen to know if, when using a card like this, the four drives show up like one big drive (because they're all on the same card), or do they show up as separate drives?
 
The Sonnet M.2 4x4 is the ONLY card listed with official MP7,1 compatibility at this time. It’s restricted to certain NVMe blades.

You’re going to have to wait until MP7,1 release and individual user testing to push that further, unless manufacturers directly start listing or advertising MP7,1 compatibility.
 
the asus don't work under macOS

use sonnet or highpoint card - both holds 4 NVMe (best with samsung 970!)
 
Thanks for your reply!

Would a card like the ASUS Hyper M.2 X16 Card V2 be a good choice as well? It's a lot cheaper than the Sonnet adapter:
https://www.asus.com/Motherboard-Accessories/HYPER-M-2-X16-CARD-V2/

Cards that split one PCIe slot into multiple M.2 slots can be implemented in two ways. One way is called port bifurcation. They simply route the lanes into multiple devices. This is cheap, but requires specific support from the chipset and firmware because you're plugging multiple devices into one slot. That's why they only work on some systems and motherboards.

The other way is to use a PCIe switch. This is standards compliant and should work on any system, but more expensive.

 
I would hope any multi-lane PCIe 3.0 switch should be compatible with the 7,1 Mac Pro.

With that said... Bifurcation of PCIe lanes on the Pro platform is long overdue and it wold be great to see multiple PCIe SSd's accessible without a switch. Why a feature that can be provided on many PC/EFI based motherboards hits the cutting room floor of the platform is truly a shame. Then again. - what can anyone expect from a T2 based architecture except than a consumer platform.
 
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I would hope any multi-lane PCIe 3.0 switch should be compatible with the 7,1 Mac Pro.

With that said... Bifurcation of PCIe lanes on the Pro platform is long overdue and it wold be great to see multiple PCIe SSd's accessible without a switch. Why a feature that can be provided on many PC/EFI based motherboards hits the cutting room floor of the platform is truly a shame. Then again. - what can anyone expect from a T2 based architecture except than a consumer platform.
Port bifurcation is a cheap solution designed to lower the build cost, it was never ever intended to be a Pro solution:
  • Needs firmware and OS help to work besides hardware support.
  • It's not on the fly, has to be configured before loading the OS.
  • Only can split the lanes, can't share it. Hypothetical example, if you have an 8x slot, with a 4 blade card, every blade gets two lanes, don't matter if you use one or three.
  • Lane bifurcation itself has limited ways that can be configured.
It's a useful resource to have, but it is what it is, a cheap way to connect PCIe devices without the cost and performance of a PCIe switch.
 
Port bifurcation is a cheap solution designed to lower the build cost, it was never ever intended to be a Pro solution:
  • Needs firmware and OS help to work besides hardware support.
  • It's not on the fly, has to be configured before loading the OS.
  • Only can split the lanes, can't share it. Hypothetical example, if you have an 8x slot, with a 4 blade card, every blade gets two lanes, don't matter if you use one or three.
  • Lane bifurcation itself has limited ways that can be configured.
It's a useful resource to have, but it is what it is, a cheap way to connect PCIe devices without the cost and performance of a PCIe switch.

Interesting opinion. That must be why bitrufication is reserved for PC workstation and server motherboards. Otherwise every low-end mobo would feature the tech.

On the T2 front. Clearly a consumer oriented interface and has no business on the MP as its been nothing but problems in the imac pro.
 
Interesting opinion. That must be why bitrufication is reserved for PC workstation and server motherboards. Otherwise every low-end mobo would feature the tech.

On the T2 front. Clearly a consumer oriented interface and has no business on the MP as its been nothing but problems in the imac pro.
Low end motherboards don't even have PCIe slots or lanes to split. Even bifurcation being a cheap solution to PCIe switches, is a costly solution to the low end market.
 
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