Are you using FAT32 or HFS?
But anyway you see it, unless you delete and add so many songs, you have no need to defrag this drive. In fact, I would do a restore over defrag, since that is much faster (restore then adding songs) and less strenuous on the HDD.
1G 5GB/2G 20GB/3G 20GB and 40GB/4G 20GB/Photo 30GB/5G 30GB Blk/1G Mini Blue/2G Mini Green/iPod Shuffle 512MB/iPod Nano 4GB Blk iPod Touch 8gb
Yeah, I own a lot of iPods. Yeah, I know it's a problem. Yeah, I know I should join iA(iPods Anonymous). Stop making new iPods Apple !!!