I am running an iMac G-3 Power PC with a Mac OS 10.3.9. Do I need to defragment my Hard Disk and, if so, what is the simplest way to do this? Thanks.

Probably not.

Most unix-like systems dont have issues with fragmentation. I believe that as the OSX filesystem (HFS+) is journalised, it defrags when idle (but dont take my word for that)

You do not have to defragment your hard drive (for reasons stated above), but if you do not leave your Mac running (all the time / at night) then some essential scripts may not be performed.

You can perform these maintenance tasks manually with apps like these:
Onyx
Main Menu
Cocktail
(among others)

These are available on sites like MacUpdate and VersionTracker

You can also run them yourself in Terminal without a GUI based app if you wish:
[ site with info about this ]

Being a longtime Mac user, I've seen this question before. I am quite certain that defagging cannot be done on Macs. If you hear of something to the contrary by all means let me know, but I even checked the Mac OSX reference manual and it didn't mention anything on that subject matter.

Edward

>I am quite certain that defagging cannot be done on Macs.
Fragmentation isn't as big a deal as it used to be. With large hard drives, hard drive caching, and more intelligent filesystems, data isn't fragmented in the first place as often. However, defragmenting *can* be done on Macs, in fact, it's done on-the-fly. A feature built into the Darwin kernel called "Hot-File-Adaptive-Clustering" helps keep fragmentation low, automatically.

In the case that fragmentation is more serious, there is a third party tool called iDefrag that can do the job instead. Or, you can simply wipe the disk and reinstall.

TechTool Pro defrags the main HDD and any external I've used since being on Leopard. How much it helps, I'm not sure. It's sort of like Disk Warrior's optimization.
Not sure if it's compatible with 3.9. I still use Disk Warrior on my eMac that has that.

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