On Mon, 31 Mar 2008, vze284qe@verizon.net wrote:

On Sun, 30 Mar 2008 21:25:28 -0400 Mike Frysinger <vapier@gentoo.org> wrote:

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On Sunday 30 March 2008, Chuck Noyes wrote:

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I had mounted an external usb drive /dev/sdb2 onto /media/sdb2 and was coping several mega-bytes of files to it when I got some I/O errors. Then I noticed that all of my /dev/sdb* files were missing from /dev.

When I do an ls -al /dev, all the files are there except the sdb files.

How can I get these back? I'm running Ubuntu 'gutsy' 2.6.20-16-generic.

the device nodes only exist as the kernel thinks the device exists. if you got I/O errors and then the device nodes disappeared, the kernel probably detached the device. so even if you made the device nodes by hand, it wouldnt matter as the kernel still wouldnt think the device was attached. review your `dmesg` and if need be, unplug/plug in the USB device. -mike

Well....this is really strange!

I booted up another kernel a 2.6.18, and I noticed that the /dev/sdb* files were still missing! All of the other /dev files were there.

So I shut down the computer - power off, unplug, remove battery (it's a laptop) and waited a minute. I reinstalled the battery, plugged it in and booted up the usual kernel, et voila...the /dev/sdb* files reappeared!! All looks good! Even Linux has some strangeness I guess.

I don't know what caused this in the first place...transient lightning bolts? spurrious darktrons?

A few thoughts... Is the external USB drive self-powered? Did you power-cycle it at any point? The device itself might have gotten wedged. It might have shown up as /dev/sda* on some of those interim reboots, depending on whether there were any other usb storage devices present. "lsusb", and the tail command Eric suggested, are your friends. What is sda currently? [ these work on 2.6.23, not sure about earlier kernels ] $ cat /sys/block/sda/device/model $ cat /sys/block/sdb/device/model Anyway, glad to hear it at least works again. -Jamie