Maximizing speed of USB 2.0 clients on USB 3.0 hub

Question

I need to connect 2 USB 2.0 cameras and one USB 3.0 SSD to a single USB 3.0 hub. I would like both of the cameras to run at 480 Mbps and the SSD to use the rest of the bandwidth. Is this possible?

I intend to use following setup::

• USB 3.0 hub
  • USB 3.0 SSD client
  • USB 2.0 camera client
  • USB 2.0 camera client

Will the cameras run at 2 x 480 Mbps like this? If no, is three a setup (maybe with additional USB hub) with which they will? Can I influence how much of the bandwidth each of the clients (2.0 or 3.0) uses other than by trying to control the transfers on my SW side? (so that the SSD wont use more than about 4 Gbits - not really sure how this could be done in SW now)

Answer 1

USB 3.0 and USB 2.0 use different buses and even different wires in the cable. The USB 3.0 device will probably have no slowdowns from one or more USB 2.0 devices on the same hub.

However the two USB 2.0 devices will compete with each other for bandwidth meaning that if they both want all the bandwidth of USB 2.0 (480 Mb/s) either one will not negotiate and leaving only one working, or they both will not work. It's possible the devices will also figure out they don't have enough bandwidth and auto-negotiate down to "share" nicely, but video will likely be choppy or even low resolution.

The other limitation may come from power. While the two different USB versions use different data buses, they may share power hardware in the hub and/or computer. A powered hub may alleviate some issues here, but it's still likely you would only get one device on each hub working if they use a lot of USB Bandwidth.