不會的就放這邊 最近要搬家了 請至https://mcutodo.blogspot.com

當掛載出現問題且無法正常缷載(Device is busy)時，可以考慮使用以下強制缷載的參數試試看。

最後是用 umount -l /dev/sr0 就立刻缷載成功。

man umount

-f Force unmount (in case of an unreachable NFS system). (Requires kernel 2.1.116 or later.)
-l Lazy unmount. Detach the filesystem from the filesystem hierarchy now, and cleanup all references to the filesystem as soon as it is not busy anymore. (Requires kernel 2.4.11 or later.)