2018 Mac Mini Consistent External NVME TB3 Data Rates?

[Ginger]

I have a 2018 Mac Mini i7 6 core w/ 32GB ram, 1TB internal running Mojave 10.14.6. I've got one 2k 24" monitor off the HDMI port, another off a TB3/USB-C port via an adapter to DVI. Both USB 3 ports are used - one for non-power stuff like keyboard, etc. The other has a powered USB-A 3 dock hanging off it. Nothing else on the TB3/USB-C ports.

I just purchased a Crucial P2 2TB PCIe M.2 2280SS NVME SSD for external storage. It's rated up to 2400 R/1900 W. I've tried 2 different 10Gbps USB-C cases (Sabrent & XCellon) and I cannot get data rates above 954 write/ 798 read. Iv'e tried different cables, different ports, etc. It is on the second set of TB3 ports as I am aware they have separate buses and I didn't want to hang it off the bus being used for video thinking there would be more bandwidth on the unused side.

What gives? I've read that cables can be finicky but how many should I try? Are the cases this inconsistent? If so, does anyone know of a reliable case that can take advantage of the full specs of the drive? Is it because this is a mac mini issue I should hang it off a powered TB3 dock?

How can I get closer to the speeds the drive is rated for? Also, oddly, if I run Aja, change cables, run it again, I get INSANELY low rates. If I do a restart and change nothing else, run Aja Drive Test again, then I get the same 954/798. This happens with multiple drives so seems like a mac mini/software issue.

Anyone know what the deal is here? Very frustrating.

[dominicperry]

I'm not following entirely here, but I think you are trying to run a very fast drive in a USB3 enclosure, off a USB3 hub. So you won't get TB speeds, you'll get USB3 speeds (most likely 5 or 10 Gb/s - unlikely to be a USB 3.2 Gen 2x2 hub running at 20Gb/s) compounded by losses transferring from USB to USB to NVME.

I'm assuming your transfer rates quoted (954/798) are MB/s (megaBYTES) a second.
- 5Gb/s (gigaBITS a second) is 625 MB/s.
- 10Gb/s is 1250 MB/s.

So my guess is that your hub is running at 10Gb/s (in fact, I've just re-read and you state the enclosure is this speed) for a maximum of 1250MB/s and the loses you see from multiple protocol and hub hops are taking it down to 954MB/s.

Given that no one else has answered here, can I politely suggest that you will probably get better answers from a forum like MacRumors, where there's plenty of discussion about storage speeds.

Dominic

[dominicperry]

Looks like TB enclosures are available for NVME 2280 disks - you still won't get speeds like an internal drive but you might get 1500MB/s+

I'm no expert on this, so please do your research - I can't guarantee that these will work. These links are to UK sites, but I'm sure these products or similar are available in the US.
One last thing - if you connect anything else to the TB port on the MacMini, you will get the lowest common denominator - i.e. the lowest speed of any connected peripheral. So dedicating a port is a necessity for the best speeds.

https://www.sabrent.com/product/EC-T...osure-ec-t3ns/

https://www.flexxmemory.co.uk/storag...le-fan-cooled/

https://www.orico.shop/en/thunderbol...-sky-gray.html

Dominic

[Ben Jenssen]

I have several thunderbolt enclosure with fast ssds connected directly and they are never over 500/500 mb/s. I think it'll have to be pcie connected to get multiples of that. Like the mini internal.

[Ginger]

Originally Posted by dominicperry

... but I think you are trying to run a very fast drive in a USB3 enclosure, off a USB3 hub. So you won't get TB speeds, you'll get USB3 speeds (most likely 5 or 10 Gb/s - unlikely to be a USB 3.2 Gen 2x2 hub running at 20Gb/s) compounded by losses transferring from USB to USB to NVME.

No, I'm not running off a hub. I'm directly connected to the mini. So there should be no loss. The enclosures I'm using are 10Gbps so I wasn't expecting TB speed, but I was expecting over 1000mbps which I am not getting. Additionally, the speed is inconsistent even though I'm not changing anything. I can get drastically different speeds running Aja several times in a row without changing any connections or anything else. It's incredibly frustrating.

I will post in other forums if nothing productive comes from here.

[Ginger]

Originally Posted by dominicperry

Looks like TB enclosures are available for NVME 2280 disks - you still won't get speeds like an internal drive but you might get 1500MB/s+

I'm no expert on this, so please do your research - I can't guarantee that these will work. These links are to UK sites, but I'm sure these products or similar are available in the US.
One last thing - if you connect anything else to the TB port on the MacMini, you will get the lowest common denominator - i.e. the lowest speed of any connected peripheral. So dedicating a port is a necessity for the best speeds.

https://www.sabrent.com/product/EC-T...osure-ec-t3ns/

https://www.flexxmemory.co.uk/storag...le-fan-cooled/

https://www.orico.shop/en/thunderbol...-sky-gray.html

Dominic

Thanks for the links. I'm aware of TB3 bus loading. This is currently on a bus with nothing else connected. I'm not expecting 1500mbps+ with a 10Gbps enclosure, but I did think getting over 950 would be possible. The more disturbing thing is the inconsistency when absolutely nothing has changed.

[JFreak]

1500 theoretical 1000 practical, that is pretty normal