Comment 26 for bug 1007394

St├ęphane Graber (stgraber) wrote :

Right, so it doesn't have any mapper entry open, making it more likely to be a kernel problem (/dev/sda1 hanging in I/O wait) than anything else.

Can you perhaps try something like:
dd if=/dev/sda1 of=/dev/zero bs=1024 count=1

And see if that hangs as well?

(I'm only assuming the I/O wait is on /dev/sda1, there's no clear proof of that but it's certainly the most likely)