I came across this article on a so called advanced compression feature in OnTap: https://communities.netapp.com/docs/DOC-14329. There is a bunch of marketing fluff in the beginning of the article till you come to the second section where the real technique is illustrated. This is a simple idea being drummed up a bit. There is nothing special compared to what I had implemented for and the OpenSolaris livecd years back. It is the very same feature.
Don’t believe me? Head over to my livemedia slides: http://www.osdevcon.org/2007/slides/osol_livemedia.pdf (slide 13). This is the presentation I delivered at the First OpenSolaris Developer Conference in 2007 in Berlin. It was hosted by the good folks of the German Unix User’s Group.
At the high level there are but a couple of differences with the NetApp implementation. The OnTap version of course provides write capability which I did not implement since I was dealing with CDROMs. OnTap uses a compressibility threshold of 25% while I used 12% in the livecd case.
When I wanted to leave SUN and was looking for a change I had interviewed briefly with NetApp but decided not to pursue it for the sake of BeleniX at that time (OpenSolaris+ZFS was NetApp competition). However I had put all details of my CDROM Filesystem I/O scheduler and transparent compression implementation with URLs in my resume.Who knows if someone in NetApp decided to pull the good ideas from that into their product – ha.