You can turn on vSphere Fault Tolerance through the vSphere Web Client.
When Fault Tolerance is turned on, vCenter Server resets the virtual machine's memory limit and sets the memory reservation to the memory size of the virtual machine. While Fault Tolerance remains turned on, you cannot change the memory reservation, size, limit, or shares. When Fault Tolerance is turned off, any parameters that were changed are not reverted to their original values.
Connect vSphere Web Client to vCenter Server using an account with cluster administrator permissions.
- In the vSphere Web Client, browse to the virtual machine for which you want to turn on Fault Tolerance.
- Right-click the virtual machine and select .
- Click Yes.
The specified virtual machine is designated as a Primary VM, and a Secondary VM is established on another host. The Primary VM is now fault tolerant.