28 or 14 usb mass storage devices on raspberry pi4
Posted: Wed Jan 22, 2020 9:14 am
Hello!
I'm sorry, if this is in the wrong section, but I don't really know, what is causing my problem.
My application: I want to connect 28 mass storage devices to my rpi4. I've built a system with four 7-port-usb-hubs. These hubs are powered with 20 amps in total. On my rpi3 just 14 devices showed up in /dev. On my rpi4 21-24 devices are showing up. At first I thought, that it is a problem caused by too low current. So I tried everything with Y-cables in addition. Same result. So now am I at the point where I think, that this is not caused by too low current. Raspberry has a 5.1V 3A source too. In /boot/config.txt I set max_usb_current=1. Still the same result.
Now I decided to just use 14 devices per raspberry and use two of them connected via ethernet. But sometimes 7 devices disconnect and reconnect after 2-3 seconds (this happens every 2-5mins). This is not caused by the hubs, as I used different hubs from different manufacturers. 7 devices on their own are stable everytime. But if I just plug one device into the second hub, it sometimes is reconnecting.
I also tried to connect this "hub tree" with all my 28 devices to an expensive laptop (~2000 euros) with windows 10. All 28 are recognised.
Cheap desktop pc with windows 10 (~200 euros): 21
Rpi4: 21-24
Rpi3: 14
Is it possbile that the usb hardware is just not "fast" enough to handle that many devices?
At first I want it to work with two rpi4 each connected to 14 devices without reconnecting to have a backup-solution.
But in the best case it should work with only one rpi4.
Does anyone know, what is causing this problem?
Sorry for my bad english,
terror404
Pi: Raspberry Pi 4 Model B
OS: Raspbian Buster
I'm sorry, if this is in the wrong section, but I don't really know, what is causing my problem.
My application: I want to connect 28 mass storage devices to my rpi4. I've built a system with four 7-port-usb-hubs. These hubs are powered with 20 amps in total. On my rpi3 just 14 devices showed up in /dev. On my rpi4 21-24 devices are showing up. At first I thought, that it is a problem caused by too low current. So I tried everything with Y-cables in addition. Same result. So now am I at the point where I think, that this is not caused by too low current. Raspberry has a 5.1V 3A source too. In /boot/config.txt I set max_usb_current=1. Still the same result.
Now I decided to just use 14 devices per raspberry and use two of them connected via ethernet. But sometimes 7 devices disconnect and reconnect after 2-3 seconds (this happens every 2-5mins). This is not caused by the hubs, as I used different hubs from different manufacturers. 7 devices on their own are stable everytime. But if I just plug one device into the second hub, it sometimes is reconnecting.
I also tried to connect this "hub tree" with all my 28 devices to an expensive laptop (~2000 euros) with windows 10. All 28 are recognised.
Cheap desktop pc with windows 10 (~200 euros): 21
Rpi4: 21-24
Rpi3: 14
Is it possbile that the usb hardware is just not "fast" enough to handle that many devices?
At first I want it to work with two rpi4 each connected to 14 devices without reconnecting to have a backup-solution.
But in the best case it should work with only one rpi4.
Does anyone know, what is causing this problem?
Sorry for my bad english,
terror404
Pi: Raspberry Pi 4 Model B
OS: Raspbian Buster