need to defrag?

Apparently not :

There are two kinds of fragmentation: file fragmentation and volume fragmentation. File fragmentation refers to what happens when a file gets broken into lots of tiny pieces so that every little nook and cranny of the hard disk can get used.

Volume fragmentation (the kind that Norton looooves to point out) just means that all of the files aren't crammed together in one (mostly) contiguous part of the hard disk. File fragmentation can be bad--volume fragmentation: not really.

In Classic Mac file systems (HFS and HFS+) and DOS/Windows file systems (FAT, FAT32, NTFS), an "optimized" disk means that not only are files themselves contiguous, but all those files are jammed together in a tidy block. It seems efficient and neat, however... from the second that a disk has been defragged, it becomes more and more inefficient. All that packing together of data means that the moment a temp file is deleted, part of your business proposal is probably going to get stuffed in it's place--instant fragmentation.

In UNIX, however (like MacOS X's underpinnings), typical filesystems use high degrees of _volume_ fragmentation to combat file fragmentation. Anybody who has had some sectors go bad on a hard drive knows that lots of file fragments mean the possibility of a much greater number of corrupted files.

In short (oops, too late). Defragging in the UNIX (and now MacOS) world is more likely to do harm than good.
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Depends on your use of the computer. Normally, I'd say no - just like Apple does. There _are_ some cases (mainly working with big audio and video files) where fragmentation can still be a problem. But there I'd go with backups and formatting the disks used instead of defragmenting, which can take a _lot_ more time.
 
The "hot zone" is where OS X stores frequently-used files for faster access. In the earlier days of OS X, it was one of the main reasons people recommended against defragmenting. It could decrease performance, they said, because it would muck with the hot zone. (I personally think that was a silly argument, since OS X would just reestablish its hot zone in a matter of days, but anyway...) Most modern defragmenters respect the hot zone.

I agree with Fryke: most people don't need to worry about it. It's simply impossible for me to say whether YOU would benefit from defragmenting, but as a rule, if you don't have very good reason to believe you would, then you probably wouldn't. I also agree with Fryke about backing up and reformatting rather than using dedicated defragmenters. It's a lot safer. And sometimes faster, as well.

There's been a lot of discussion on this topic on these boards, so use the search feature if you want more info.
 
Doesn't every update in OS X automatically defrag? I thought that was what the "Optimizing" process does, in the seemingly endless final stage before you have to restart your Mac.
 
Not true. Diskwarrior or reformatting will repair this damage.
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But the problem may come back again - if they aren't marked as being bad. And if there are bad sectors its usually the start of something bad...

Doesn't every update in OS X automatically defrag?
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I believe its only with large files.
 
MrTAToad said:
I believe its only with large files.
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Actually, it's only with small files (<20MB). Also, OS X makes no effort to keep free space unfragmented. In fact, it actively fragments free space so that files that are edited will not be instantly fragmented (this is generally a good thing). These two factors are what makes fragmentatation a problem when you deal with large files, like graphics and video.
 
this is why people have separate volumes for video-editing usually.

having said that, i used to have my itunes library on a seperate external disk, sorted and organised by itunes, with nothing else on it. try defragging one of those volumes in windows. it's impressive, in that you get one huge block of 0% fragmentation, and that's it. a perfect volume.
 
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