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

vSphere HA restarts a virtual machine with Flash Read Cache on a target host that meets the Flash Read Cache, CPU, Memory, and overhead reservations. If unreserved flash is insufficient to meet the virtual flash reservation, vSphere HA does not restart a virtual machine. If the target host does not have sufficient virtual flash resource available, reconfigure the virtual machine to reduce or drop the Flash Read Cache.