For farming i am using Raspi4 with Ubunto desktop 64bit.
It is powered with 5v, 3A power adaptor.
I have a not powered USB hub (model ORICO 7 Ports transperant usb 3.0) with in tot 8 external hard drives connected to.
All external hard drives are with their own power supply. And some of they have also their own integrated usb hub. In that way i have connected some of the discs.
The problem is that when i restart the PI from the power, it wont fire up. The only way to fire up is to disconnect the usb hub.
After it is booted, i can connect the hub and all works fine.
Please advice how to solve this problem, as my PI is installed on a remote location and is hard to ask someone to unplug/plug th hub. ?
btw, when you say that with such a disc with integrated hub i am wasting my slots, is that mean that if i bye 8 discs, each with 2 additional usb, they will count as 3 per disc and total will become 24 slots in the controller host ?
As i know, thats above the RPI4 limit of 20 slots. So this mean my 8th disc will have problems and will start to randomly disconnect, right ?
I think I understand you said, this problem is cause by your usb hub.
your hub don’t have a Reverse current protection,
the external power supply will reverse the current to the PI when the PI main power down, resulting in failure to start or other problems. You can try it when there without external power supply. It should be work normal, you need a usb hub with Reverse current protection
Although some cheap hubs are marked with yes, they do not. If you know how to test, you can test whether there is countercurrent protection
As it Involving high-frequency circuit and high-speed data transmission, it can not be simply filtered.
Sorry,I don’t have these links, you can ask somebody who are using these type of usb devices or ask the seller to confirm
I have found workaround.
I just removed the hub and pugged it in one of the external discs usb ports, and then i plugged this disc in the RPi. I suppose the external discs have some reverse current protection, because the problem was solved.
Anyway, i will update here when i get the VKUSRA USB Hub also.