defragment Mac drive or not?

[briananderson@v]

what's the deal here? Snake oil or actual remedy? Is it necessary to actually defragment a Mac hard drive or does it really do it by itself? Some experts claim Mac automatically defrags it's drives and some say on files only 20mb or less. Does defrag really help to optimize performance or is this just a lot of Hooey! Dazed and confused by all the claims and counterclaims. All opinions appreciated. Thanks

[jbennet]

Mac automatically defrags it's drives

windows xp does that too, but only when its left idle, so on Xp its best to run it manually

Does defrag really help to optimize performance

It increases performance. Really

Is it necessary to actually defragment a Mac?

i dont think they have issues with fragmaintation. Unix based systems like OSX tend to have much less problems with it that windows based ones

[John A]

Here it is, right from the horse's mouth:
http://docs.info.apple.com/article.html?artnum=25668

In short, under normal circumstances you shouldn't need to defragment an HFS+ volume, as Mac OS X tends to prevent fragmentation in the first place in the way that it caches the writing of files to the disk and automatic optimization of the volume. And if you've really reached the point where your system performance is affected by fragmented files on your hard disk, it's probably time for a fresh installation of your operating system anyway.

Although I should throw in that iDefrag is probably the best defragmentation tool out there on the Mac platform, but it should only be used in exceptional circumstances.