Ever got the error ‘devise is busy’ when trying to umount?
I got this error once and I was CERTAIN no important scripts were running on it.
This is how I umounted:
sudo umount -l /mnt/mysql_data/
The -l is ‘lazy’
All I had to do is RTFM
“Note that a file system cannot be unmounted when it is `busy’ – for
example, when there are open files on it, or when some process has its
working directory there, or when a swap file on it is in use. The
offending process could even be umount itself – it opens libc, and libc
in its turn may open for example locale files. A lazy unmount avoids