Why does umount say, “device is busy”?
That just means you’re still using the filesystem on that device. Unless something has gone very wrong, you should be able to unmount after you stop using the filesystem. Here are a few ways you might be using the filesystem without knowing it: • NFS might be exporting it. Stopping the NFS service will unuse the filesystem. • A process might be holding open a file on the filesystem. Killing the process will unuse the filesystem. • A process might have some directory on the filesystem as its current working directory. In that case, you can kill the process or (if it’s a shell) cd to some other directory that’s not on the fs you’re trying to unmount. The lsof command can be helpful in finding processes that are using files.
