GA Release Dates:
S2D 2019: Oct 2018
S2D 2016: Oct 2016
2nd generation software. Because Storage Spaces Direct (S2D) is an integral part of the Windows Server platform, the first GA version of S2D was introduced as part of the GA release of Windows Server 2016 in October 2016. The second GA version of S2D was introduced as a part of the GA release of Windows Server 2019 in October 2018.
Microsoft recommends deploying Storage Spaces Direct on hardware validated by the Windows Server Software Defined (WSSD) program. For Windows Server 2019, the first wave of WSSD offers was launched in mid-January 2019.