The following checklist contains cluster, host, and virtual machine requirements that you need to be aware of before using VMware Fault Tolerance.

Review this list before setting up Fault Tolerance. You can also use the VMware SiteSurvey utility (download at to better understand the configuration issues associated with the cluster, host, and virtual machines being used for VMware FT.

You must meet the following cluster requirements before you use Fault Tolerance.

Host certificate checking enabled. See Enable Host Certificate Checking.

At least two FT-certified hosts running the same Fault Tolerance version or host build number. The Fault Tolerance version number appears on a host's Summary tab in the vSphere Client.


For hosts prior to ESX/ESXi 4.1, this tab lists the host build number instead. Patches can cause host build numbers to vary between ESX and ESXi installations. To ensure that your hosts are FT compatible, do not mix ESX and ESXi hosts in an FT pair.

ESX/ESXi hosts have access to the same virtual machine datastores and networks. See Fault Tolerance Best Practices.

Fault Tolerance logging and VMotion networking configured. See Configure Networking for Host Machines.

VMware HA cluster created and enabled. See Creating a VMware HA Cluster. VMware HA must be enabled before you can power on fault tolerant virtual machines or add a host to a cluster that already supports fault tolerant virtual machines.

You must meet the following host requirements before you use Fault Tolerance.

Hosts must have processors from the FT-compatible processor group. It is also highly recommended that the hosts' processors are compatible with one another. See the VMware knowledge base article at for information on supported processors.

Hosts must be licensed for VMware Fault Tolerance.

Hosts must be certified for Fault Tolerance. See and select Search by Fault Tolerant Compatible Sets to determine if your hosts are certified.

The configuration for each host must have Hardware Virtualization (HV) enabled in the BIOS.

To confirm the compatibility of the hosts in the cluster to support Fault Tolerance, you can also run profile compliance checks as described in Create VMware HA Cluster and Check Compliance.


When a host is unable to support VMware Fault Tolerance you can view the reasons for this on the host's Summary tab in the vSphere Client. Click the blue caption icon next to the Host Configured for FT field to see a list of Fault Tolerance requirements that the host does not meet.

You must meet the following virtual machine requirements before you use Fault Tolerance.

No unsupported devices attached to the virtual machine. See Fault Tolerance Interoperability.

Virtual machines must be stored in virtual RDM or virtual machine disk (VMDK) files that are thick provisioned. If a virtual machine is stored in a VMDK file that is thin provisioned and an attempt is made to enable Fault Tolerance, a message appears indicating that the VMDK file must be converted. To perform the conversion, you must power off the virtual machine.

Incompatible features must not be running with the fault tolerant virtual machines. See Fault Tolerance Interoperability.

Virtual machine files must be stored on shared storage. Acceptable shared storage solutions include Fibre Channel, (hardware and software) iSCSI, NFS, and NAS.

Only virtual machines with a single vCPU are compatible with Fault Tolerance.

Virtual machines must be running on one of the supported guest operating systems. See the VMware knowledge base article at for more information.