6.0.1

Table 3‑2. Differences Between Legacy FT and FT (Continued)
Legacy FT FT
vStorage APIs - Data Protection
backups
Not supported Supported
Eager-zeroed thick .vmdk disk files Required Not required because FT supports all
disk file types, including thick and thin
.vmdk redundancy Only a single copy Primary VMs and Secondary VMs
always maintain independent copies,
which can be placed on different
datastores to increase redundancy.
NIC bandwidth Dedicated 1-Gb NIC recommended Dedicated 10-Gb NIC recommended
CPU and host compatibility Requires identical CPU model and
family and nearly identical versions
of vSphere on hosts.
CPUs must be compatible with
vSphere vMotion or EVC. Versions of
vSphere on hosts must be compatible
with vSphere vMotion.
Turn on FT on running VM Not always supported. You might
need to power off VM first.
Supported
Storage vMotion Supported only on powered-off VMs.
vCenter Server automatically turns
off FT before performing a Storage
vMotion action and then turns on FT
again after the Storage vMotion
action completes.
Not supported. User must turn off FT
for the VM before performing the
Storage vMotion action and then turn
on FT again.
vlance networking drivers Not supported Supported
Additional Requirements for Legacy FT
In addition to the differences listed for legacy FT, it also has the following unique requirements.
n
Your cluster must contain at least two FT-certified hosts that run 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.
n
ESXi hosts must have access to the same virtual machine datastores and networks.
n
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 use Fault Tolerance, a message indicates that the VMDK file must be converted. To perform the
conversion, you must power off the virtual machine.
n
Hosts must have processors from the FT-compatible processor group. Verify that the hosts' processors
are compatible with one another.
n
The host that supports the Secondary VM must have a processor that supports Fault Tolerance and is
the same CPU family or model as the host that supports the Primary VM.
n
When you upgrade hosts that contain fault tolerant VMs, verify that the Primary and Secondary VMs
continue to run on hosts with the same FT version number or host build number (for hosts before
ESX/ESXi 4.1).
NOTE If you designated a VM to use legacy FT before you upgraded the hosts in the cluster, that VM
continues to use legacy FT after the host upgrade.
vSphere Availability
58 VMware, Inc.