This article provides guidance to vSphere customers and server partners on vSphere Fault Tolerance (FT).

VMware vSphere Fault Tolerance provides continuous availability to virtual machines, eliminating downtime and disruption in case of a server host failure. The feature is dependant on the server CPU.

VMware vSphere 4.x and 5.x support “Legacy FT”: a fault tolerance feature for uniprocessor virtual machines. Legacy FT requires a separate fault tolerance certification by server partners in order to be officially supported.

VMware vSphere 6.0 supports both uniprocessor and multiprocessor virtual machines; it is the default for vSphere 6.0 hosts. Because FT supports SMP for vSphere 6.0, it is also referred to as “SMP-FT”. The FT feature can work on Intel Sandy Bridge (Intel Xeon E3 and E5 series processors) and above and AMD Bulldozer (AMD 3200, 4200, 6200 series Opterons) and above CPUs. The server must be equipped with a minimum of 6 CPU threads for FT to provide adequate performance. Legacy FT is still supported in vSphere 6.0 for backward compatibility with pre-existing virtual machines, however we do not encourage continued use.

VMware ESXi 6.5 supports only FT. The Legacy FT feature is removed from ESXi 6.5. However, vCenter Server 6.5 can still manage Legacy FT virtual machines on ESXi 6.0 and ESXi 5.5 hosts.

For VMware vSphere 6.x or later, the FT feature certification is solely based on the CPU. To simplify the CPU selection process, a new CPU property, "Supports SMP-FT," is added to the VMware Compatibility Guide (vCG) for CPU Series. If CPU’s Supports SMP-FT property is checked, the server with the CPU is supported. To check the CPU property, visit the vCG for CPU Series at http://www.vmware.com/resources/compatibility/search.php?deviceCategory=cpu.

As part of phasing out Legacy FT, VMware is not offering it on new processor generations launched after 2015 in any vSphere release. This means that Legacy FT will not be extended to include support for Intel Xeon E3-1200-v4, E3-1200-v5, Xeon D-1500, and any future Intel processors in any vSphere 5.x or 6.x release.