VCHA configuration fails to deploy due to vSAN error "There are currently [X] usable fault domains. The operation requires [Y] more usable fault domains"

Products

• VMware vCenter Server

Issue/Introduction

• VCHA configuration fails with status seen in GUI: 
  

  Status
  
  Cannot complete file creation operation.
  There are currently 4 usable fault domains. The operation requires 2 more usable fault domains.
  Failed to create object.

• vpxd.log shows: 
  error vpxd[07007] [Originator@#### sub=Default opID=###] [VpxLRO] -- ERROR task-###--  -- Datacenters -- com.vmware.vcenter.vcha.cluster.
deploy: :vim.fault.CannotCreateFile
--> Result:
--> (vim.fault.CannotCreateFile) {
..
..
-->          message = "Failed to create object."
-->       },
..
..
-->          message = "There are currently X usable fault domains. The operation requires Y more usable fault domains."
-->       }
-->    ],
-->    file = "xxxx - Upgraded-Passive (Cannot Create File)"
-->    msg = "Cannot complete file creation operation."
• VCHA is being deployed in a vSAN enabled cluster 

Environment

• VMware vCenter Server 8.x
• VMware vSAN (All versions)

Cause

• The vSAN cluster does not have enough healthy, active fault domains to satisfy the Failures to Tolerate (FTT) rule defined in the assigned VM Storage Policy
• In vSAN, a fault domain is typically an individual ESXi host, an explicitly defined group of hosts, or the vSAN Witness appliance

Resolution

Please follow the resolution steps outlined in KB 326856