I have read an article on physical file defragmentation on a SAN or RAID system http://www.raxco.com/products/perfectdisk2k/whitepapers/pd_raid.pdf.

The gist of RAID/SAN defrag is that

a) Not all defrag tools are compatible with SANS/RAID arrays.

b) It is the LCN numbers that get defragged rather than the physical files and this improves performance.

There is a benefit in performance of having the data striped across the disks in a RAID/SAN but the LCN benefit from having contiguous blocks.

Has anyone got any practical experience with this?