During the last five years, enterprise-class storage arrays have evolved from all-HDD, to Hybrid HDD/SSD, to all-flash media inside. Leading storage vendors also offer NAS, SAN and unified versions of each. Until this year, the array portfolio of leading storage vendors included only all-HDD arrays with an option to add some flash. The breakthrough year for the industry came in 2014, highlighted by the introduction of all-flash storage arrays from leading vendors including Dell.