When you upgrade hosts that contain fault tolerant virtual machines, ensure that the Primary and Secondary VMs continue to run on hosts with the same FT version number or host build number (for hosts prior to ESX/ESXi 4.1).

Verify that you have cluster administrator privileges.

Verify that you have sets of four or more ESXi hosts that are hosting fault tolerant virtual machines that are powered on. If the virtual machines are powered off, the Primary and Secondary VMs can be relocated to hosts with different builds.


This upgrade procedure is for a minimum four-node cluster. The same instructions can be followed for a smaller cluster, though the unprotected interval will be slightly longer.


Using vMotion, migrate the fault tolerant virtual machines off of two hosts.


Upgrade the two evacuated hosts to the same ESXi build.


Turn off Fault Tolerance on the Primary VM.


Using vMotion, move the disabled Primary VM to one of the upgraded hosts.


Turn on Fault Tolerance on the Primary VM that was moved.


Repeat Step 1 to Step 5 for as many fault tolerant virtual machine pairs as can be accommodated on the upgraded hosts.


Using vMotion, redistribute the fault tolerant virtual machines.

All ESXi hosts in a cluster are upgraded.