Disk Full

Santa and Banta work in a software company. One day, they were to move their m/cs to another building. Banta was having a tough time carrying his machine.
Santa : "My m/c has 500 MB disk. See how easily I am carrying it. Yours has just 250 MB. Can't you carry even this much?"
Banta : "But yours is empty and my disk is full"!!!