I have just implemented a file server with a RAID-5 array (four spanned drives, total capacity equal to three drives with 1/4 of each drive storing redundant parity informaiton, RAID is all handled in the hardware controller).

I am using the NTFS file system on this RAID array. Significant thrashing will occur (files of varying sizes will be constantly added and removed in willy-nilly fashion).

Must this RAID drive be defragmented regularly?

The only reason I ask is because the OS sees only a "virtual" drive from the RAID controller. I don't see how a third-party defragmenter could do any good in this situation. Is my hunch correct?