Monday, February 27, 2012

Testing vSphere 5 FT in a VMWare Workstation lab

Studying for VCP 5 requires a home lab for walking through the installation steps, learning to manage every single feature of vSphere 5 and getting real hands-on experience.

If you wanted a cost effective solution for your home testlab, you have probably chosen to run everything in a VMware Workstation environment.

Though nesting your vSphere environment inside VMWare Workstation has let you test ESXi installation, vCenter appliance configuration, vMotion, Storage vMotion and much more, there certainly is something you are struggling to enable: Fault Tolerance (FT).

In fact, even if you could get a VM configured for FT, you probably get the following message when powering it on:

'Record/Replay is not supported on this CPU for this guest operating system.'

To work around this issue, you'll have to use BT-based record/replay, which means adding the following option to your FT-enabled VMs:

  • replay.allowBTOnly : true
  • replay.allowFT : true
  • replay.supported : true

These settings are found at VM-level under 'Edit Settings / Options / General / Configuration parameters' (note that this tab can be accessed only with your VM powered off).

The 'replay.allowFT' and 'replay.supported' switches must just be set from false to true while 'replay.allowBTOnly' must be added as a new row.

Of course this setting can be added directly to the vmx file, but for sure you knew that if you are heading to be a VCP.

For more information on Binary Translation check this and this. And for a VCP 5 study guide, check my other blog post here.


  1. If I set replay.allowFT to true I get the following error when botting the vm: This virtual machine is configured for 64-bit guest operating systems. However, 64-bit operation is not possible. Longmode is disabled for this virtual machine.
    virtualization technology and vt-x are enabled on the physical machine vmware workstation is runnig on and Virtual Intel vt-x/ept is enabled on the nested esxi host vm. Any idead?

  2. Owen, what version of Workstation are you using? You need version 8, and your configuration file for the VM should have this line:
    guestOS = "vmkernel5"
    If this doesn't help, please be more specific on your computer hardware (model, cpu) and software versions and I'll be glad to help.


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