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furryspider 08-13-2004 10:48 AM

Can't mount 2 usb-storages after one another on same port?
 
Hi,

I'm on Slack10, using at times a 128MB USB-RAM-Stick as well as a digital camera. Both I can access through /dev/sda1.

However, whenever I mount either of the storage devices, and unmount them after the data transfer, I cannot mount the other one anymore. When trying to, mount tells me that /dev/sda1 isn't a valid block device. I am able to mount the SAME storage device again, though.
E. g.:
Mount Camera, copy contents, unmount camera
then:
a) mount usb-ramstick => not a valid block device
b) mount camera again => no problem

I noticed that two processes become active whenever I mount a usb storage device, and stay active even after I unmount the device. The processes are:
usb-storage-0
scsi_eh_1

Does anybody know what's going on?

Thanks,
FurrySpider

Dark_Helmet 08-13-2004 02:06 PM

I don't have a definitive answer, but a guess...

The system might save device information when you mount it, meaning that it associates /dev/sda1 with a particular USB device identifier. If you plug in another device that no longer matches, the system might then be forced to associate it with a different device: /dev/sdb1 for instance.

Give that a shot; try to mount the second device using /dev/sdb1. Like I said, it's a guess, and the worst thing that could happen is the system tells you "/dev/sdb1 is not a valid block device" :)

furryspider 08-14-2004 02:24 PM

Spot on Dark_Helmet! It works like you said!
I was actually trying to find the place where the system would store that 'device information', so I could go and tamper with it. I just didn't, and still don't have a clue where that might be.

Anyway, following your directions I don't have to bother anymore. Thanks!

Dark_Helmet 08-14-2004 03:03 PM

Glad I could help!

And the "device information" I referred to earlier is probably stored in RAM somewhere. It might be part of the USB modules loaded for the device, stored in some special kernel memory, or any number of other places. Since you could plug in either device after a reboot and access it as /dev/sda1, that suggested the information was lost on reboot, and that implies RAM...

Anyway, useless trivia... the important part is, you're good to go ;)


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