Flash Read Cache is supported by High Availability (HA).

When vSphere HA restarts a virtual machine configured with Flash Read Cache, the virtual machine is restarted on a host in the cluster where the Flash Read Cache, CPU, Memory and overhead reservations are met. vSphere HA will not restart a virtual machine if unreserved flash is insufficient to meet the virtual flash reservation. You must manually reconfigure a virtual machine to reduce or drop the Flash Read Cache, if the target host does not have sufficient virtual flash resource available.