Fulfill the following prerequisites before starting the installation:
  1. Compatible versions for vSphere, vCenter must be installed and setup for the cluster i.e. vSphere 6.7 and vCenter 6.7.
  2. All ESX hosts must have access to same network so that when VM starts on other host it should access to same network.
  3. Each host in the HA cluster must be able to do DNS resolution of any other host in the cluster.
  4. Minimum 2 ESX hosts are required for setting up HA. However, to ensure redundancy and maximum Fault Tolerance protection, you should have a minimum of three hosts in the cluster.
  5. VM files (except for the VMDK files) and other configuration files must be stored on shared storage so that it should be available from any esx hosts. Acceptable shared storage solutions include Fibre Channel, (hardware and software) iSCSI, vSAN, NFS, and NAS.
  6. High bandwidth ethernet link between ESX hosts.