MP 1,1-5,1 Slow PCIe NVME?

[iChan]

"Slow" is a relative term. It's much faster than the SATA SSD I had before, but I was expecting a lot closer to 1500MB/s, so I feel maybe I'm losing about 20-30%.



My Setup:

Mac Pro 4,1 -> 5,1, 144 bootrom, Mojave, RX580, WhateverGreen mod, Innie Mod.

Aqua Computer kryoM.2 evo PCIe 3.0 x 4
Sabrent 256GB Rocket NVMe PCIe M.2 2280

I got the small one just to test the speed, and I'm not that impressed with this speed. Might try a Samsung instead. I really don't know what the bottleneck might be. The Sabrent SSD is rated p to 3100MB/s.

I have yet to upgrade the CPU or RAM. So the CPU is still stock 2 x 2.26 (E5520). And RAM was supplied with 1x 16GB 1066MHz and 1 x 8GB. Dunno if CPU/RAM setup can have an effect on PCIe NVME speeds.

Does anyone else have experience with this drive/adapter combo? Is my result in-line with what I should be expecting? Would I get better results with a Samsung Evo 970?

 

[mikas]

Yes you would get closer to 1500MBps with Samsung EVO 970 with Black Magic.

Writes seems to be in accordance to specs, but Reads do not.
https://www.sabrent.com/product/SB-...gh-performance-solid-state-drive/#description

Real world performance could be evaluated better with for example AmorphousDiskMark.
Better random speeds e.g. Seq and 4K results would tell more about normal use, and Seq QD32 and 4K QD32 would tell about special cases of sustained continuous speeds (which cases do exist).

About SATA SSD versus NVMe SSD:
The last line 4K (random QD1) makes us realize that the difference in normal everyday use is not so much between a SATA SSD and NVMe SSD. At least not in everyday use.

There are use cases the difference makes a day for someone. Like Black Magic reveals, large continuous transfers would be an example of that. And so would an application which benefits of multiple simultaneous 4K transfer speeds, aka multiple parallel requests to read and write. There PCIe NVMe generally would shine too over SATA SSD. In everyday usage, ordinary SATA SSD would be just fine, some benchmark numbers could be even better over another (SATA SSD/NVMe SSD).

 

[iChan]

@mikas Thanks for all that info, very interesting!

I downloaded AmorphousDiskMark like you suggested. I'd seen that benchmark SW it before, but never noted what it was. So thanks for that.

Anyway, here are the results:

I'm not entirely sure what I'm looking at, but the numbers in "Seq" are similar to the BlackMagic ones. So I'm guessing that's what BlackMagic is giving me: sequential read & writes. Which makes sense for video.

But what is "Seq QD32"? I know QD is Queue Depth... those numbers seem a lot closer to spec. Again, I'm guessing here, but maybe the Queue is acting like some sort of buffer? To keep the data flowing in/out of the drive more consistently?

Out of interest, I ran the benchmark on the Intel SATA2 SSD as well. The 4K had a strange result of writing much faster than reading. I ran the test twice to confirm. This is odd, and far outperforms the Sabrent in 4k write speeds.

 

[mikas]

There is a lot to it, like: IOPS. You can see IOPS measurements too in the app if you hover over the result with mouse.

There is a forum too there you can go read at Amorphous:

I haven't read it, but there is a thread called: FAQ: how come write is faster than read?
Not much traffic there though.