Device or Resource Busy
An attempt to access or modify something failed as it is already in use. Probably the most common reason for seeing this is trying to unmount a disk partition while processes have open file descriptors on that device.
(your shell now using the floppy disk)
$ umount /floppy umount /floppy: device is busy
If you want to find out why a disk is busy
fuser -vm /floppy
will list the processes that are using that disk :)
8 pages link to EBUSY: