I'm wondering what is the maximum number of USB devices the Linux kernel can manage? Does this depend on the root-Hub or something else, too?
Is there a way to increase this maximum number?
I need to do this, because I've ran into problems while trying to write to a large amount of USB sticks. To do this, I have a setup as follows:
There is 1 computer running Ubuntu Linux, with 3 (active) HUBs attached to 3 USB ports of this machine. All of those three HUBs are 7 port HUBs. To 6 of those 7 ports, more HUBs are attached. This gives me the number of 3 * 6 = 18 HUBs in the "second" layer. Each of these HUBs is an active 7 port HUB, too. There is a USB stick attached to every port of those second layer HUBs. In total I have 126 USB Sticks connected to the computer.
I have a script that searches for all USB disk devices (through listing /dev/disk/by-path/ ). Each of the USB disk devices is then first partitioned, written to using cp and then made bootable using syslinux. This is NOT done in parallel!
The problem: I only get 105 USB disk devices using
ls -la /dev/disk/by-path | grep usb | grep -v part | wc -l
The LEDs of the sticks in 3 rows (one row corresponds to one HUB in the second layer) are off, too.
How do I get all of those sticks to work? (Or possibly even more?)