Server restarts when i connect too fast to multiple devices

Submitted by Jaco9307 on #1

I currently have 20 devices connected to a Linux server. When i connect to them in smaller batches, it works as intended.
If i select more than 5 or so, it some times crashes, and the list of devices disappears before loading up again. Looking at the server i can see that all the USB connections get disconnected and the reconnect.
I get a windows message saying a USB malfunctioned and some times when this happens, I also get a error on the client saying "operation not permitted (-1)"
While just connecting to a few at a time does avoid the problem, it also kicks everyone else who is using the devices off.
So if someone isn't careful, they could kick everyone else off their devices, possibly during updates or similar.
It seems pretty inconsistent as to when it happens, some times it even happens when i connect to 3 devices.
Any idea as to what is going on and how to avoid it? If a hardware update is necessary, its doable

Submitted by Michael on Fri, 2019/09/20 - 09:58

#2

It definitely sounds like a power issue. I think when you initially connect to the usb devices they pull more current than available from the hub and so they drop off. I think you need to good quality separately powered usb hub. What hub model are you using at the moment?

Submitted by Jaco9307 on Fri, 2019/09/20 - 19:12

#3

I am currently using two icy box ib-a6113. They both have a separate 12V 5A power supply.
I think its a network thing though. When trying it again later in the day, The issue was entirely gone and i could connect to all 20 at once with no issues, multiple times.
Trying it again now during the more active hours i get the same issues again.

Submitted by Michael on Sat, 2019/09/21 - 11:37

#4

If you dont mind could you reproduce the problem, then send me the /var/log/syslog from the server so i can see what the kernel is doing. mail [at] virtualhere.com (mail[at]virtualhere[dot]com)

Submitted by Michael on Wed, 2019/09/25 - 08:34

#5

Thanks for sending me the log

Im pretty sure this message is the culprit

Sep 24 15:22:16 hek-G8-Lenovo kernel: [1121357.189372] hub 2-1.2.1.4.4.4:1.0: Unsupported bus topology: hub nested too deep

Basically you have connected too many downstream hubs together, can you flatten the tree somehow, e.g by plugging a hub into a higher level hub instead