umount /mnt/[driveName]says that
device is busythen it means that some process is still accesing the drive..
To check what process is accessing the drive, try
fuser -v /mnt/[driveName]..
In my case, i got
So all i do is kill the konqueror process with a
and the device umounts successfully
Great source for understanding the /etc/fstab file that has the filesystem configuration information: http://www.tuxfiles.org/linuxhelp/fstab.html