I've seen many threads about this, and I know that with Mac's we don't really need to defragment because HFS is based on the BSD file system (right?) and it does it in the background but with relatively small files. But my problem is, I have a 320GB hard drive in my macbook, and I've had Parallels/large files being moved around/deleted. I had a bootcamp partition before and had gotten rid of it. (So I could re-partition a larger portion) Now, when I go to the BC Assistant, it can't partition the drive [It say's unable to move files and fails. Once it actually made the partition, and I saw my Free space drop, but it ultimately failed with the same rror again] . And taking a look at the drive map iDefrag gives me, I don't have enough continuous space. That's fine, I ran iDefrag but now I have LESS continuous space: This is after I ran iDefrag once through (it took about 24 hours to finish), and it seems as if it just spread all my files out evenly. Should I run it again until it does its job? Or are there any other tried and true methods to clean and reorder my system? (Short of backing up and reinstalling OS X) Thanks!