Introducing vSphere SMP Fault Tolerance
Since the introduction of vSphere Fault Tolerance (FT) in vSphere 4, you have been limited to protecting workloads only with a single vCPU. vSphere 6.0 introduced SMP-FT, a complete re-write of vSphere Fault Tolerance that allows you to protect VMs with up to four vCPUs. So, even if you have a machine that you want to protect that has only a single vCPU, under vSphere 6.0 it will be delivered using the new SMP-FT technology. The only time you will see FT on a vSphere 6.0 cluster is for virtual machines that were enabled for FT on a version of vSphere cluster prior to 6.0, which was then upgraded to vSphere 6.0.
Previous versions of vSphere FT used a technology called vLockstep, but it was limited to a single vCPU per FT-enabled VM. vSphere SMP-FT uses a new technology called FastCheckpointing to scale beyond a single vCPU. Whereas vLockstep would take an input and execute it simultaneously on both the primary and secondary VMs, FastCheckpointing...
