Several months ago VMware announce vSphere APIs for IO Filtering (VAIO) as a solution to implement 3rd Party Software-Defined Data Services in vSphere 6.0. VAIO offers partners the ability to put their technology directly into the IO stream of a VM through a filter that intercepts data before it is committed to disk.
It’s a good and efficient idea to implement features like caching or replication without the need of external components (or appliance) or kernel modules like today.
But this a partner program (like the Virtual Volumes) and unless partners have not developed this kind of solutions, it is useless.