VMware HA & FT - Important Note

[Alexey]

While using VMware HA will protect you against the failure of an ESX/ESXi host, VMware HA won’t—by default—protect you against the failure of the guest operating system. An OS-level cluster, on the other hand, does protect against the failure of the guest operating system.

VMware FT won’t protect you against guest operating system failure—a crash of the OS in the primary VM generally means a crash of the OS in the secondary VM at the same time—and it won’t protect you against application failure.