Windows Server 2016 introduces a new feature called "Fault Domain Awareness". With Fault Domain Awareness the physical placement of devices on the node-, chassis- and rack level, can be properly defined. In the configuration a node can be assigned to a chassis and the chassis can be assigned to a rack. When Fault Domain Awareness is configured, S2D will spread the data intelligently across individual Fault Domains.
Effectively, when a rack fails the data is already located on one or two cluster nodes located in other racks depending the chosen protection level and physical deployment.
Microsoft, S2D [SDS]/2019, Datacenter
Rack Failure Protection, Reads/Writes, Data Availability