Testing Mac mini M2 usb ports speed for music production

[aero+]

Hello,
In an effort to better spread my SSDs for audio I’m running some tests on my new Mac mini M2, and I’m finding some very unexpected results.

The major surprise is that when I hook a usb hub to one of the USB-A ports (let’s say port B), the read speed of the SSD directly connected to other port (port A) drops down dramatically, compared to when no hub is connected to port B (this particular Mac mini has 2 USB-A ports and 2 T4 ports).

It would be great if someone with a similar Mac mini (M2 octacore) would be so kind to try and replicate this test and share its findings

A couple of readings:

A Crucial X6 SSD rated for 800 Mbps directly connected to USB port A without anything else connected to USB port B

crucial x6>mac usb A di destra.png

The same Crucial SSD on the same port but this time with a 10GBps hub connected to port B with nothing attached to it

crucial X6 a sx and orico 10gbs a dx senz a nulla attaccato a dx.png

[BertKoor]

The USB-A ports on a M2 Mac Mini are rated up to "only" 5 Gbps, so these would be formerly named USB 3.0 SS.

Note the small letter b for bits, not a capital B for Bytes. To convert bits into bytes you can divide by 8 giving 625MBps but for safety I'd divide by ten, to factor in the serial protocol could have a start & stop bit for each byte: USB 3.0 SS = 500MBps max, in theory.

It is not uncommon that multiple ports are on a shared chip serving both ports. Maybe the hub is interfering, keeping it busy, even with nothing connected.

It would be interesting to see test results with the SSD drive connected via the hub.

[aero+]

Yes sorry about the 'b' typo.

Interesting hypothesis, I also tried the same configuration on an older intel Mac mini and I got no hub interference at all.

If connected via the 10 Gbps hub I have similar results as the second test, roughly, write: 400 MB/s, read: 150 MB/s

It would be great if someone with a similar Mac could replicate the test (I tried with multiple hubs and SSDs already)

[Funky40]

hmm, interesting.
M2pro / 2 SSDs on 2x USB-C Hubs

Samsung T7 has 370MBs (USB-C) / and my older Samsung 850Evo or so has 430MBs (USB-A) .
hmm, both on a own USB-C hub, into a own USB-C port, each.
TB4/USB-C ports 3 and 4 on my M2

[aero+]

Thank you, would you be so kind to test the usb a ports too? First One ssd in one usb a port and nothing in the other usb a.
Then keep the ssd in that same port and attach a usb hub of any kind to the other usb a and see if the Ssd on the first usb a port speed decreases … if you can spare the time

I know it makes little sense but that’s what I’m seeing

[BertKoor]

Also worth a try: get a USB-C -> USB-A adapter so the SSD drive can be connected exclusively to a Thunderbolt/USB-C port. Because if you want to use it at speeds close to the upper bandwidth limit of what USB3 can do, then don't let it share that.

[Funky40]

Thank you, would you be so kind to test the usb a ports too?

I´ve heard you.
But i just had no lust to move there any connections around since i *really* have a cable mess there, and have had some problems recently.

[rACatkvr]

Thank you, would you be so kind to test the usb a ports too? First One ssd in one usb a port and nothing in the other usb a.
Then keep the ssd in that same port and attach a usb hub of any kind to the other usb a and see if the Ssd on the first usb a port speed decreases … if you can spare the time

I know it makes little sense but that’s what I’m seeing

Makes sense if the ports are running off the same controller within the Mac.

[aero+]

Yes maybe that’s what’s happening which a surprise, as my older Mac mini, as an example, doesn’t suffer from the same architecture.