Mac Mini (2018) Misconfigures USB 3.1 (gen 2) Hub using Mojave (both 10.14.2 & 10.14.3)

an alternative is to put the external drives on a StarTech HB30A3A1CST coming off one of the macmini's USB-A ports . It's a self-powered USB 3.0 hub that has a 2A output @ 12VDC, and supports 5 Gbps

https://www.startech.com/Cards-Adapters/USB-3.0/Hubs/4-port-usb-3-hub~HB30A3A1CST

how many times does 560MB/s go into 5 Gbps?

Can you post a screenshot of the device tree that shows this?

This should include devices connected to the hub.

Can you post a screenshot of the device tree that shows this?

This should include devices connected to the hub.

Let me make sure I understand this correctly:

1. The empty hub correctly shows as USB 3.1, but...
2. The second you plug in the USB Flash Drive the entire mess reverts to USB 2.0, but...
3. When you remove the USB Flash Drive the hub correctly shows as USB 3.1.

Am I getting this?

It appears the Flash drive is USB 2 and the hub is reverting to USB2 speed.

Yes, the 10 Gb/s speed should be preserved. However, for your case it does not make any difference since your disks

https://www.g-technology.com/products/portable/g-drive-mobile-ssd-r-series#0G06052

only have a transfer rate of

Transfer Rate

Up to 560MB/s

I'm planning on connecting two G-Technology drives, both 1TB G-DRIVE mobile SSD Durable Portable External Storage - USB-C (USB 3.1 Gen 2) - [0G06053] to the macmini 2018 w/Mojave via that same StarTech 4-Port USB-C Hub [HB31C4AB]. The G-Technology product page says the kit contents include both a USB-C to USB-C and a USB-C to USB-A cable, the latter is what I would use to connect to the hub

would this preserve USB 3.1 Gen 2 (10Gb/s) speed? I'm not aware of any difference in USB-C to USB-A cables themselves, and believe that the speed would be limited by the lowest USB implementation used by any device on the hub

thank you, David. I understand the concern, and had hoped that they would consume less power than conventional, spinning drives. Unfortunately these economical SSDs do not have a separate power adapter, so I will follow your direction and check with the manufacturer. I may be able to find a powered enclosure; otherwise I'll have to bite the bullet and go for the more expensive drives that are self-powered

it's precisely because of the (relatively) slow transfer rate that I wanted to avoid occupying the limited number of TB3 ports :-(

I do very much appreciate your clearing up my bus question :-)

assuming bus power is not an issue, at 560MB/s how many G-Technology 1 TB SSD drives [0G06053] can I attach to a 3.0 supporting 5 Gbps, like StarTech's [HB30A3A1CST]

how many times does 560MB/s go into 5 Gbps?

just an fyi (for demonstration purposes includes inexpensive solutions, no RAID or multidisk JBOD configurations)

@ 10 Gbps USB 3.1 gen 2 supports 1.25 GB/s

so a hub would support

2 x G-Technology 1 TB mobile SSD drive [0G06053] @ 560MB/s (2 TB capacity available)

https://www.g-technology.com/products/portable/g-drive-mobile-ssd-r-series#0G06053

assuming power requirements were within the 5A bus power limit (need confirmation on this 5A number!)

or 3 x G-Technology 1 TB ev RaW SSD [0G04759] within G-Technology ev Solo docks [0G04547] @ 400MB/s (2 TB capacity available)

https://www.g-technology.com/products/portable/g-drive-ev-raw-ssd#0G04759

https://www.g-technology.com/products/accessories/g-dock-ev-solo#0G04547

with power provided by the docks :-)

--- alternatively

@ 40 Gbps Thunderbolt 3 supports 2750 MB/s

so a single G-Technology 1 TB mobile Pro SSD drive [0G10311] @ 2800MB/s (only 1 TB capacity available)

https://www.g-technology.com/products/portable/g-drive-mobile-pro-ssd#0G10311

with power provided by a direct TB3 connection

what configuration to use would depend on how you have your data distributed (fixed vs hot-swapable disks), the capacities required, and costs

any needed corrections or qualifications are appreciated