I purchased a USB 3.0 Hub with external power supply. When attaching identical USB3 platter-based hard drives to the hub, CrystalDiskMark reports drive speeds of 80-90MB/s (sequential reads) for the drive plugged in to the first port. For the drive plugged in to the second port, CrystalDiskMark reports drive speeds of 36-39MB/s.
In all tests, only one drive was being accessed at a time.
Does this sound like the controller chip in the hub is poorly designed or would these be the expected results? If the results are expected, can you explain why?
UPDATE
According to USB Device Tree Viewer v3.1.7, the hub always adds a "USB 2.0 MTT Hub" with a PID of 0610, and a VID of 05E3.
About half the time, when I plug in the hub, it also adds a "USB 3.0 Hub" with PID 0612 and VID 05E3.
When attaching hard drives to the hub, they sometimes get enumerated under the "USB 2.0 MTT Hub", even when the "USB 3.0 Hub" is present.
Interestingly, according to Windows 7 (via USB Device Tree Viewer), the "USB 2.0 MTT Hub" uses the USB3 driver iusb3hub.sys. Why?
Answer
USB 3.0 hub controllers with VID=05E3 and two PIDs 0610 and 0612 are manufactured by Taiwanese company Genesys Logic, according to Linux ID database. The chip controller is GL3520. This silicon chip is USB-IF certified, which means that it passes all requirements WHEN PROPERLY MOUNTED ON PROPER PCB with PROPER POWER SUPPLY and PROPER TRACE ROUTING. And this is the questionable part.
Here is a review of your hub product:
It says in part:
low-power devices like USB 3.0 card readers operate flawlessly off the hub – but devices which are a bit more power hungry like my SSD in a box fail to operate properly
I suspect that the power distribution along this "product" is not up to the task, and that's why the SuperSpeed links do not always work and are flaky, especially when two of HDD drives are connected and the link falls into USB 2.0 mode, with corresponding data transfer speeds. The hub product doesn't have USB-IF certification logo, probably for that very reason. You got what you paid for.
The fact that both hubs (2.0 and 3.0) operate under the same USB3 common driver is normal.
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