I can't add more than 12 USB drives to my linux farming server

Hi Guys,

I’m running Ubuntu 20.04

I’d read that Linux can handle virtually unlmited hard disks, but when I add my 13th disk via USB it isn’t recognised. I’m finding it very hard to find help online as most articles indicate there is no limit.

Any advice?


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Ive only read about a USB-limit of 128 or 256.
12 rly is much lower, than I expected.

There are 128 adresses on a USB bus, but that doesn’t mean you can connect so many devices.
As with all things computers it is much more messy


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I had the exact same issue today with 11th device.

I have 2 7-port USB hubs (Amazon.co.uk)

One is full, the other one has 3 devices connected to it. I tried to plug in a 4th device and it wasn’t recognized.

I currently have free space in the devices already plugged in so didn’t spend too much time but it will soon become an issue.

I’ll post here if I find a solution. Also will bookmark this thread in the meantime.

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One hub to split one port into 7? Is the original 3.0 port capable of allowing this?

Yes, you can plug 7 devices into the hub while using 1 USB port in the computer.

I’m not sure about USB 3.0 being capable. Since they are directly connected to the machine I imagine the speeds should be enough for farming.

USB 3.0 HUB is usefull for farming, but not for plotting, and I recommend use powered ones, even u’ve powered external HDD’s.

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The ones I use are powered

good for all of us.
less plots you have, more money we can win.

Thanks a lot guys, I will try one hub, see how it goes…on a totally separate topic - you guys remember X-Files?

That was a great link @Yae, thanks!

So, I’m fairly convinced now that its my main USB host on the motherboard that is limiting me, not the hub. I’ve ordered a new PCIe USB 3.0 card and will test it out tomorrow to see if it resolves the matter. I’ll update my findings here


I guess they are not getting enough power, maybe better do with a external “self-powered” hub.

How do you prevent the spinning drives from sleeping in Ubuntu - for the life of me, I couldn’t get the settings to stick…

I use crontab to schedule a write to each disk every 5 minute.

date > /mnt/Disk8TF/Io.txt

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This is getting fairly off topic @Kwyjibo - best to add a new question.


@richardwhatever Did you manage to find a solution for this?

So, i bought a dedicated USB 3.0 card, bypassing the USB host on the motherboard, and now it works fine.

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I see. I’m farming on a laptop so I guess that’s not an option for me.

This will depend on the USB controller on the motherboard, type of hub you’re using and as well the device you use. For example, the USB controller allow up to 127 devices. You plugged a 8-port USB hub and each ports on the USB hub take up 2 of the 127 devices allowed. You plug a USB HDD that maybe take up 2 USB of the devices allowed. In total after you plugged in the USB hub and 1 USB device into that hub, you may have already used up 2-4 or maybe more of the USB devices allowed. Sorry if I explained it correctly. Also as well power requirement.

To get exact number, look up your motherboard USB controller, USB hub and device specification.