Lots of acronyms :)

VMAX - EMC VSP - HDS VAAI - VMWare's Storage API

I really liked a post by the storage anarchist as it quite eloquently explains what is happening and a great benefit of VAAI. Granted the post primarily speaks about the eraze part and I'm not that knowledgeable about VAAI itself to tell if there are any other features - but there is - at least according to this article on vmetc.com. This does not focus on the same two features that the anarchist mentioned. Maybe the storage anarchist did not want to mention all of these other features because they actually do work quite well for arrays that are behind the VSP.