Amazon’s global infrastructure is broken up into Regions. Each Region supports the services for a given geography. Within each Region, Amazon builds isolated and redundant islands of infrastructure called Availability Zones (AZ).
With VMware Cloud on AWS, ESXi hosts traditionally reside in an AWS Availability Zone (AZ) and are protected by vSphere HA. A new feature called Stretched Clusters for VMware Cloud on AWS is designed to protect against an AWS availability zone failure.
Now applications can span multiple AWS availability zones within a VMware Cloud on AWS cluster. vSAN Fault Domains are configured to inform vSphere and vCenter which Hosts reside in which Availability Zones. Each Fault domain is named after the AZ it resides within to increase clarity.
Some of the advantages are
More information on Stretched Clusters for VMware Cloud on AWS can be found here.