vSphere HA monitors a cluster of ESXi hosts and, in the event of a host(s) failure, it attempts to restart virtual machines that were running on the failed host(s) onto other available hosts in the cluster. This is more of a fault-recovery solution, and the virtual machines do incur a downtime, which translates to application/service downtime. There can be mission-critical applications in your environment that cannot tolerate such a downtime. Virtual machines hosting such applications require continuous availability—which can be achieved by enabling FT.
With vSphere FT enabled on a virtual machine, the guest operating system or the application will never incur downtime due to an ESXi host failure.
In this recipe, we will learn how to configure Fault Tolerance on VMs.