vSAN - The current topology that contains stretch cluster is not supported

Products

• VMware SDDC Manager / VCF Installer
• VMware vSAN

Issue/Introduction

When performing a precheck using SDDC Manager, you witness this error. 

Environment

VMware Cloud Foundation 9.0
VMware vSAN 9.0.1.0

Cause

Using VMware Cloud Foundation Fleet Deployment with Site High Availability (Across Zones) and Enhanced High Availability via a vSAN stretched cluster requires a minimum of 8 hosts. With fewer than 8 hosts, you cannot use a vSAN stretched cluster and must instead choose either the vSphere Single-Rack Cluster Model or the vSphere Multi-Rack Cluster.

Design	Attribute	Details	Implications
VMware Cloud Foundation Fleet Deployment with Site High Availability (Across Zones) Design	Enhanced High Availability	Provides fault domains to ensure site high availability.   Distributes resources across fault domains to minimize the impact of hardware failures.	Deployments across two fault domains enhance availability but require careful planning to meet latency and bandwidth requirements.

Resolution

• Read the Deploying a New VMware Cloud Foundation or VMware vSphere Foundation Platform documentation.
  
  
• Plan carefully and select a deployment model that fits your available resources.
  
  
• Redeploy a new VCF instance.