When configuring your cluster, you should be aware that not all vSphere features can interoperate with Fault Tolerance.
The following vSphere features are not supported for fault tolerant virtual machines.
Snapshots. Snapshots must be removed or committed before Fault Tolerance can be enabled on a virtual machine. In addition, it is not possible to take snapshots of virtual machines on which Fault Tolerance is enabled.Note:
Disk-only snapshots created for vStorage APIs - Data Protection (VADP) backups are supported with Fault Tolerance. However, legacy FT does not support VADP.
Storage vMotion. You cannot invoke Storage vMotion for virtual machines with Fault Tolerance turned on. To migrate the storage, you should temporarily turn off Fault Tolerance, and perform the storage vMotion action. When this is complete, you can turn Fault Tolerance back on.
Linked clones. You cannot use Fault Tolerance on a virtual machine that is a linked clone, nor can you create a linked clone from an FT-enabled virtual machine.
Virtual Volume datastores.
Storage-based policy management. Storage policies are supported for vSAN storage.
VBS enabled VMs.