http://www.datacore.com/storage-virtualization-viewpoint-blog/12-09-05/Software-Defined_Storage_for_Software-Defined_Data_Centers.aspx ...The storage hypervisor’s main role is to virtualize storage resources and to achieve the same benefits – agility, efficiency and flexibility – that server hypervisor technology brought to processors and memory. To fully achieve this goal, a storage hypervisor must meet certain requirements.
It must improve the utilization of existing storage resources; improve application performance to virtualized storage resources; integrate with heterogeneous hypervisors and popular operating system environments (Windows, Linux, UNIX, etc.); support existing physical and new virtual storage platform resources; and it must automate and simplify storage management. For an overview of the requirements of a storage hypervisor, please view the Storage Hypervisor Checklist: Nine Things to Look for In a Storage Hypervisor.