[dfox]

The idea behind defragmentation is to make the files themselves consecutive, which is not done in any way in this game, which makes it somehow confusing. The fact that DOS/Windows defrag also moves the used space to the beginning of the block device is mostly an implementation detail (and the experience with unix filesystems seems to indicate that it is actually better strategy to intentionally fragment the files by allocating the space almost randomly as long as the fragments are "large").