This research examines storage best practices for hosted virtual desktop deployments by Gartner. Some stuff I violently disagree with. 

The article has some very good information in it, at a 20,000 feet view of course. One of the reasons why I think this article is incomplete, is that there is no mention of using local storage (note that the URL has 'Netapp' in it so guess who was sponsoring that :-)). Why on earth would you NEED to use SAN storage in VDI? That is almost the same thing as upgrading a company lease car plan so everyone can drive a Ferrari. 

Which brings me to my next point. One of the quotes is "To avoid simultaneous outages of all virtual desktops, users should specify, configure, and operate storage for the highest levels of data protection and availability. Technology and practice for recovery from logical failures must be selected for appropriate RPO and RTO."

I think there needs to be a very important distinciton here: only use this DR functionality for data that matters: user data. Please dont waste money on replicating and snapshotting OS Data unless you NEED to. You probably NEED to do this when you are using persistent desktops. Want to drive costs down? Make sure that you use as many pooled desktops as you can. Want to drive costs down even further? Use Terminal Server if you can. That is not a joke - it is actual advice.

here's the original Gartner doc (which is still recommended reading): http://goo.gl/btoIY