Satya's blog - External HDD and ehci module

I have an external HDD which connects by USB. Ubuntu Hardy will usually automount such devices when they're connected. Today it would not mount at all, and of course I don't know the device names to mount it manually (turns out it shows up as /dev/sdc, which I tried, which didn't work). dmesg and /var/log/syslog showed that the USB system was doing something, but it wasn't recognizing the physical device, let alone enough to give me a mountable device node.

After much googling, I did "rmmod ehci_usb". 'ehci_usb' was mentioned in syslog as new high speed USB device using ehci_hcd and address (number). After re-plugging the drive, it detected and automounted. (I had previously installed the usbmount package. I don't know if that affected anything.)

This post is Google-bait for anyone with similar problems, including me. I've had USB flash drives refuse to automount before.

Update: First! Check the permissions on the /dev/ node for the device (lsusb command will give you an idea of where to look, for Bus 002 Device 004 /dev/bus/usb/002/004 is it). Also check the group on that node, find out what groups you're in with the "groups" command, and chgrp it if you have to.

Last updated: Sep 14 2008 10:06