The question has been closed for the following reason "The question is answered, right answer was accepted" by SignOff May 07 '11 at 14:17
Did you mean to say UFS, or Apple's File System: HFS+? HFS+ is a proprietary format off of UFS, derived from back in the NeXTStep days.
UFS, since you asked about it, stores data in groups of cylinders, keeping data that is more closely related to each other, physically closer together on the platter's surface. Latter versions even try to preallocate (or reserve) disk space for file expansion, thus keeping the file contiguous. (You can do this manually in NTFS by changing the cluster sizes, but depending on what you're storing, this could waste disk space.) But, if you edit a file a lot (let says a video editor), then as the reserved blocks are taken away and the file will become somewhat fragmented across the disk, but due to it cylinder location, it will still try to keep it close.
HFS+ uses some of same techniques that UFS does, being a variant of USF and USF-based. It will preallocate space for file growth. It does on-the-fly defragmentation, moving files that meet certain criteria to other parts of the disk where it can be kept contiguous. It also has "Hot File Clustering," which in its own way build a file somewhere else on the disk, then writes it to its permanent area, but this is only if the file is less than 10MB.
NTFS does thing a little differently. Its fragmentation can be limited by choosing larger cluster sizes, but this can be wasteful, unless you have large files. The MFT can also slow things down, and can be defragmented to help performance. NTFS is somewhat more complicated, in my opinion, than UFS and HFS+. NTFS's major advance was security over FAT32 with on-the-fly encryption and better file attributes. Personally, NTFS needs to do defragging in the background like the other two file systems!
I hope this helps explain things. And, anyone, if I'm wrong don't flame this answer. Please help me make corrections!
answered Nov 03 '10 at 20:54