What would the I/O access be like as I plug many USB drives into a Linux system with only 2 USB 2.0 ports and 1 USB 3.0 port? I expect I will have to have multiple levels of fan-out by plugging hubs into hubs to maximize the number of devices on each USB port.
performance on Linux system when daisy-chaining multiple USB hard-drives on USB hubs?
linux;performance;io
All of the IO to all of the drives still has to squeeze through the single USB port, so if you are trying to access them at the same time, then the performance will be poor.  If you are only accessing one at a time, then it will be no different just because there are other drives connected, but not being accessed at the time.