There are valid reasons why a spinning HD used in music or video production should be defragmented. The important one is that defragging results in one contiguous area of "free space" at "the end" of the drive -- ready to receive new streams of data from the recording process.
DiskWarrior can't do it. All DW does is repair and rebuild drive directories. It will not "relocate" the files that are actually "out there" on the drive's sectors.
You need a defragging application. Some that come to mind:
- iDefrag
- Drive Genius
- TechTool Pro
It's recommended that you BACK UP the drive in question before you run the defragger. I will mention that in practice, I've never had a defrag program muck up a drive in a way that did any damage to it (if the defrag operation was cancelled "in-progress").
Aside:
The "poor man's" way to defrag:
- Copy the contents of the drive (or partition) to another drive (or partition)
- Erase the source drive (or partition)
- Copy the contents BACK from the second drive to the first one.
This works because during a full copy, the files will be copied contiguously, and the "free space" will be left "behind" the copied files -- the results are very similar to those you would see if you ran a defragging app.