The list of things FT doesn’t like is … very long!

VMware FT is a wonderfull feature but it has so many restrictions and requirements…phew!

From KB


There are a number of requirements which must be met before FT can be setup.
  • CPUs: Limited processors must be the same family (no mix/match)
  • Requires Intel 31xx, 33xx, 52xx, 54xx, 55xx, 74xx or AMD 13xx,23xx, 83xx series of processors
  • SMP virtual machines are not supported.
  • Hardware Virtualization must be enabled in the BIOS.
  • Hosts must be in a VMware High Availability enabled cluster.
  • Storage: shared storage (FC, iSCSI, or NAS).
  • Network: minimum of 3 NICs for various types of traffic (ESX Management/VMotion, virtual machine traffic, FT logging).
  • GigE required for VMotion and FT logging.
  • Minimized single points of failures in the environment. For example, NIC teaming, multiple network switches, storage multipathing.
  • Primary and secondary hosts must be running the same build of ESX.


For VMware FT to perform as expected, it must run in an environment that meets specific requirements.
  • The primary and secondary fault tolerant virtual machines must be in a VMware HA cluster.
  • Primary and secondary virtual machines must not run on the same host. FT automatically places the secondary virtual machine on a different host.
  • Virtual machine files must be stored on shared storage.
  • Shared storage solutions include NFS, FC, and iSCSI.
  • For virtual disks on VMFS-3, the virtual disks must be thick, meaning they cannot be thin or sparsely allocated.
  • Turning on VMware FT automatically converts the virtual machine to thick-eager zeroed disks.
  • Virtual Raw Disk Mapping (RDM) is supported. Physical RDM is not supported.
  • Multiple gigabit Network Interface Cards (NICs) are required.
  • A minimum of two VMKernel Gigabit NICs dedicated to VMware FT Logging and VMotion.
  • The FT Logging interface is used for logging events from the primary virtual machine to the secondary FT virtual machines.
  • For best performance, use 10Gbit NIC rather than 1Gbit NIC, and enable the use of jumbo frames.
  • VMware FT requires that Hardware Virtualization (HV) be turned on in the BIOS. The process for enabling HV varies among BIOSs. Contact your vendor for specifics.


From another KB

For VMware FT to be supported, the servers that host the virtual machines must each use a supported processor from the same category as documented below:

Intel Xeon based on 45nm Core 2 Microarchitecture Category:

  • 3100 Series
  • 3300 Series
  • 5200 Series (DP)
  • 5400 Series
  • 7400 Series

Intel Xeon based on Core i7 Microarchitecture Category:

  • 5500 Series

AMD 3rd Generation Opteron Category:

  • 1300 Series
  • 2300 Series (DP)
  • 8300 Series (MP)

To summarize all the FT gotchas, have a look at this link VMware Fault Tolerance Requirements and Limitations.  Long list isn’t it :O

Other bloggers talking about this issue:,,


About PiroNet

Didier Pironet is an independent blogger and freelancer with +15 years of IT industry experience. Didier is also a former VMware inc. employee where he specialised in Datacenter and Cloud Infrastructure products as well as Infrastructure, Operations and IT Business Management products. Didier is passionate about technologies and he is found to be a creative and a visionary thinker, expressing with passion and excitement, hopefully inspiring and enrolling people to innovation and change.
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