If you receive the following error message from your QNAP NAS:

The file system is not clean. It is suggested that you run “check disk”

and a disk check is failed with that message:

[Mirror Disk Volume: Drive 2 3 4 1] Examination failed (Cannot unmount disk).

ssh your qnap and do the following: [php]/etc/init.d/services.sh stop && /etc/init.d/opentftp.sh stop && /etc/init.d/Qthttpd.sh stop umount /dev/md0 e2fsck -f -v -C 0 /dev/md0 mount /dev/md0 reboot[/php]

If you receive the following error while trying to unmount the device: umount: /share/MD0_DATA: device is busy try to figure out which process is still using the device: [php]# lsof +f -- /dev/md0 COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME sh 10721 admin cwd DIR 9,0 4096 16252936 /share/MD0_DATA/ lsof 29119 admin cwd DIR 9,0 4096 16252936 /share/MD0_DATA/ lsof 29120 admin cwd DIR 9,0 4096 16252936 /share/MD0_DATA/[/php]

Which indicates that your current shell is trying to use the device, simply use: cd / and umount again.

That should help