Unable to unmount USB key

[lolwhites]

I've just started using Knoppix, and am working through the "Knowing Knoppix| beginners guide. I've worked out how to mount the USB drive and save to it, but when I try to unmount it, I get the message "Device is busy". I've tried typing umount /media/sda1 into the root shell but get the same response.

Any idea what the problem is?

[Zelmo]

I don't know the cause, but I've seen this problem on USB flash drives as well as local hard drives. One way to get around it is to pass the -l flag to umount, like so:

# umount -l /media/sda1

That will release the mountpoint. Be careful with this one, though, because if the device really is still busy, it will continue to finish up any operations it was doing even after you unmount it. So it's possible to yank the USB key before it's done, and it won't complain (since it was unmounted). Because of this, don't pull it out until you're confident it really is done being accessed.

[unclebubbles]

Try right clicking the desktop icon, and in the menu that pops up, you should have an option to unmount.