Mac Pro 2019 pci-e bandwidth limitation?

Question

Mac Pro 2019 pci-e bandwidth limitation?

I have the following setup:

Mac Pro

12 Core

64 GB Ram

Amfeltec Squid Carrier Card 6 NVME

4 WD BLACK SN750 1tb NVME's

2 Barracuda 1tb NVME's

Softraid Raid 0

No matter what configuration of raid that I set up with Softraid I cannot get more than what you see below via Blackmagic and AJA System Test. According to a Softraid forum admin, the new Mac Pro pci-e is capped at 7000mb/s(I assume just for nvme drives?). Is this the case?

But when using the ATTO Disk Benchmark I get the more expected results of about 9000-10000mb/s R/W.

From what I understand all three are well respected tests but what can I make of the speed discrepancy between ATTO and the others? Which do I believe? ATTO gives me what I expected while the others do not.

Mac Pro, macOS 10.15

Posted on Apr 28, 2020 8:32 PM

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Answer 1

Apr 29, 2020 12:26 PM in response to jessefromtorrance

When you change nothing between runs of different testing programs, the differences are clearly down to testing methodology of the different tests.

Black Magic Speed Test is aimed at a practical evaluation of whether your storage can handle real-world cinematic workloads. More of its screen space is devoted to showing different resolutions and encodings than the raw speed dials. For example, it may be using the smaller block sizes more typically used in playing back movies.

Others may be using more theoretical types of testing. That you see one of those test showing the expected numbers leads me to believe everything is working as designed.

The pre-conceived notions built in those 'tests showing slightly lower results' are reflecting lower top speeds, but they do not indicate anything is broken.

Conversely, if you had ALL tests showing HALF the expected speeds, then something is clearly wrong.

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