I just did a greenfield deployment of Windows Server 2012 R2 for a big virtualization environment, and ReFS was supposed to be ideal for that kind of application. Everyone I talked to about it told me it was a bad idea, mostly because the supposed gains in certain virtualization operations wasn't worth risking being the first sucker to find a corner case in refs.sys. Also, no data recovery tools support it outside of experiments.

Does anyone actually use ReFS in production?