DDN and GPFS
I have a couple friends at DDN myself (both among the new hires) it seems from their story a lot of their key stuff is because of IBM's GPFS at least on the NAS front. They support a few other file systems as well but it seems like GPFS is the king for the most part in their books.
Only mention it because the article sort of implies IBM is the sole provider of GPFS-based NAS based on DDN hardware when DDN does the same thing without the fancy IBM branding.