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i use diskwarrior...seems to work fine. not OSX native, but still works booting into 9. you can try norton utilities, but I'm not sure if their proggie is jag compatible
 
i've looked around and there seem to be some defraging utilities for the unix variants, but i'm assuming that defragmentation is filesystem specific and that a hfs+ defrager would be needed to work on osx (is this correct?). it would make sense for apple (or me if i was not to lazy to learn how to program) to make a simple command line defrager (i'd write one myself, but all i gleaned from a "learn c in 21 days" book was how to make a prog that listed prime numbers, not very useful to anyone, which makes me wonder why they teach it to you...). making cocoa wrappers for darwin apps does not appear to be too difficult, and a program that ran the maintainence scripts, rebuilt the desktop, and ran the defragger could probably be hacked out in about an hour. better yet, apple could include it in diskutility.
 
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