What is the difference between Free Space Defrag and Free Space Defrag (Allow Fragmentation)? If i do the latter it does what i'd expect - move the data to the front of the drive and make a nice big clear space (i'm not bothered about the odd file being left behind). It does this and the files are fragmented when the run has finished. If i do the former i expected the same but for the drive to be defragmented at the same time. I expected it might take longer. However i can't see any difference between the two options. Both move the data where i expected but the data is still heavily fragmented once it's been moved. In fact the level of fragmentation is often higher than before i started, meaning i have to run a seperate defrag afterwards.... Have i missed something?