If your running a x64 bit Ubuntu or other Linux and find USB transfers hang at the end apply this fix:
echo $((16*1024*1024)) > /proc/sys/vm/dirty_background_bytes
echo $((48*1024*1024)) > /proc/sys/vm/dirty_bytes
I suggest you edit your /etc/rc.local
file to make this change persistant across reboots.
sudo nano /etc/rc.local