For cloud providers, offering predictable storage performance backed by firm SLAs will become a competitive differentiator that drives greater customer affinity and a better application experience. Many providers feel that a Software Defined Storage (SDS) frameworks hold the key to delivering guaranteed performance, yet this «software abstraction layer» is only half of the solution. SDS frameworks are dependent on the virtualized resources presented to it, and without the granular abstraction of physical storage resources, these frameworks will remain limited.