The following checklist contains cluster, host, and virtual machine requirements that you need to be aware of before using vSphere Fault Tolerance.
Review this list before setting up Fault Tolerance. You can also use the VMware SiteSurvey utility (download at http://www.vmware.com/download/shared_utilities.html) to better understand the configuration issues associated with the cluster, host, and virtual machines being used for vSphere FT.
The failover of fault tolerant virtual machines is independent of vCenter Server, but you must use vCenter Server to set up your Fault Tolerance clusters.
Cluster Requirements for Fault Tolerance
You must meet the following cluster requirements before you use Fault Tolerance.
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 Web Client.Note:
For legacy 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 legacy hosts are FT compatible, do not mix legacy ESX and ESXi hosts in an FT pair.
ESXi hosts have access to the same virtual machine datastores and networks. See Best Practices for Fault Tolerance.
Fault Tolerance logging and VMotion networking configured. See Configure Networking for Host Machines in the vSphere Web Client.
vSphere HA cluster created and enabled. See Creating a vSphere HA Cluster. vSphere 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.
Host Requirements for Fault Tolerance
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 http://kb.vmware.com/kb/1008027 for information on supported processors.
Hosts must be licensed for Fault Tolerance.
Hosts must be certified for Fault Tolerance. See http://www.vmware.com/resources/compatibility/search.php 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 Cluster and Check Compliance in the vSphere Web Client.
Virtual Machine Requirements for Fault Tolerance
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.
vSphere Fault Tolerance is not supported with a 2TB+ VMDK.
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 http://kb.vmware.com/kb/1008027 for more information.