USB 3.1 on 5,1 Mac Pro

[pierre1610]

I have a CalDigit FASTA-6GU3 Plus card in slot 4, i've installed the 10Gbps firmware but am only able to get 400 MB/s from a NVMe 970 Pro in a USB 3.1 caddy which is capable of over 1000MB/s

What gives?

Slot-4
Link width of card is x2
Link speed 5.0 GT/s

I also only have USB 3.0 Bus under system information

OS is high sierra

 

[startergo]

I have a CalDigit FASTA-6GU3 Plus card in slot 4, i've installed the 10Gbps firmware but am only able to get 400 MB/s from a NVMe 970 Pro in a USB 3.1 caddy which is capable of over 1000MB/s

What gives?

Slot-4
Link width of card is x2
Link speed 5.0 GT/s

I also only have USB 3.0 Bus under system information

OS is high sierra

Try this:
https://github.com/pciutils/pciutils
Use lspci -nnvv to see what is going on

 

[fhturner]

Anything in Slot 3?

 

[pierre1610]

Anything in Slot 3?

Yes all other slots full

is slot 4 slow then?

Slot 1 GPU
Slot 2 SSD blade
Slot 3 SSD sataiii

 

[fhturner]

Slots 3 & 4 share an x4 PCIe link. If you have activity on that SATA III SSD in Slot 3 while doing your testing, OR if you're testing by transferring from that SATA SSD to the USB3 970 Pro, that shared bus would definitely impact your results.

If that's not the case, I wonder if the card is a little bit hamstrung by the way it routes traffic to PCIe. The x2 link on a Mac Pro is going to practically max out around 750-800MB/s. If the card is dividing the eSATA and USB3 halves each onto their own x1 PCIe link, then each would be limited to about 375-400MB/s...which coincides w/ the cap you're hitting. That would seem strange for a card they're promoting as 10Gbps USB3.1, but not inconceivable...

 

[pierre1610]

Slots 3 & 4 share an x4 PCIe link. If you have activity on that SATA III SSD in Slot 3 while doing your testing, OR if you're testing by transferring from that SATA SSD to the USB3 970 Pro, that shared bus would definitely impact your results.

If that's not the case, I wonder if the card is a little bit hamstrung by the way it routes traffic to PCIe. The x2 link on a Mac Pro is going to practically max out around 750-800MB/s. If the card is dividing the eSATA and USB3 halves each onto their own x1 PCIe link, then each would be limited to about 375-400MB/s...which coincides w/ the cap you're hitting. That would seem strange for a card they're promoting as 10Gbps USB3.1, but not inconceivable...

Correction, i have a SSUBX in slot 3 which gets nearly 1GB/s

 

[fhturner]

Correction, i have a SSUBX in slot 3 which gets nearly 1GB/s

Okay, gotcha. So your SSUBX and 970 Pro are going to be contending for that shared PCIe x4 bandwidth, which tops out at about 1500MB/s. So I'd say, unless one of them is completely idle, the other will not be able to max out its PCIe connection (which in the case of the 970 Pro, would be either x1 (~400MB/s) or x2 (~800MB/s) across your CalDigit card.

What testing method are you using to get 400MB/s? Benchmark or transferring large files?

 

[bookemdano]

fhturner's explanation sounds spot on, and pretty easy to test. Remove the SSUBX you have in Slot 3 and rerun the benchmark. Or, if the SSUBX is your boot drive, take out the SATA drive in slot 2 and move the SSUBX there to re-test. I'd be curious to see the new numbers.

 

[fhturner]

Or, if the SSUBX is your boot drive, take out the SATA drive in slot 2 and move the SSUBX there to re-test.

Good thought. One thing to remember, too, is that you'll want to get that firmware updated to v138.0.0.0.0 or v140.0.0.0.0 so that your Slot 2 adapter w/ SSUBX will negotiate a PCIe 2.0 link @ 5GT/s. If you don't, it'll negotiate PCIe 1.1 @ 2.5GT/s.

 

[pierre1610]

I'm getting a x4 5.0GT/s link on my SSUBX

Just moved my PCIe cards around.

Slot1 - GPU
Slot2 - SSUBX x4 5.0 GT/s
Slot3 - FASTA-6GU3 x2 5.0GT/s
Slot4 - Sata iii Angelbird SSD x2 5.0GT/s

i still don't have USB 3.1 hub listed anywhere, only 3.0

boot drive is now slot 4

 

[pierre1610]

Re-updated the firmware and now the system reads a 3.1 USB hub, still no faster though

 

[fhturner]

What testing method are you using to get 400MB/s? Benchmark or transferring large files?