This document provides an overview of software-defined storage (SDS) concepts and discusses several SDS solutions from major vendors. It defines SDS and explains how adding a control layer allows for visibility, communication, and allocation of storage resources. Benefits highlighted include efficiency, automation, flexibility, scalability, reliability and cost savings. Specific SDS products are then profiled from vendors such as EMC, HP, IBM, NetApp, VMware, Coraid, DataCore, Dell, Hitachi, Pivot3, and RedHat.