Here's an interesting architecture around the emerging trends around storage and specifically around scale-out NAS solutions. This article does a good job explaining the needs for scale-out NAS solutions and their evolution into cloud based solutions.
The article mentions some potential solutions that include Symantec's FileStore product. FileStore is one of the fastest performing scale-out NAS solutions in the market. While VirtualStore is not mentioned in this article it is a completely software solution that can be used to gain the same benefits mentioned in the article while using existing storage hardware.
You can find more information about Symantec's FileStore and VirtualStore products at