I have changed the hub and the new one is working and not back feeding power.Your hub is faulty or badly designed/constructed, or both.
Self powered USB hubs shoudl not back feed power to the USB host device. The only time I believe this is permitted is under USB C wihen USB-PD has negotiated it but that should be over one of the CC lines not over the VBus (+5v) line.
As for drive performance, it's what I'd expect to see. Hubs add ports but do not add bandwidth. The root port on the Pi provides a totla of 5Gbps bandwidth which is then shared by all downstream devices connected to that port. Copying data between two drives connected to the hub means that data has to go over the USB link from hub to SoC twice - once on read and once on write.
The Pi 5 has sufficient bandwidth between the SoC and the RP1 (which contains the USB controller) to run both USB root ports at maximum bandwidth so you'll get better per drive bandwidth by spreading them across the two available USB 3 ports. Which may require an additional self powered hub given the USB current limit imposed by the Pi.
I have moved the hdd from the hub to a USB 3 port on the pi and ran a test rsync. The difference in performance is enormous so cheers for that tip.
It's still running hot, 51 at idle rising to 73 under stress. It's within acceptable boundaries but higher than wjat I've seen reperted for the official fan in the official case, obviously nothing to do with power backfeed though as we have eliminated that.
Statistics: Posted by sorbiegunner — Sat May 11, 2024 1:39 pm