Potential VMWare 5.1 Fault Tolerance bug/issue?

Background / Setup

I've got a fresh install of vCenter Server 5.1 and associated components.

I've taken all steps (as far as I can tell) to enable FT, and it worked the first time (yanked a power cord and watched a VM keep working -- an awesome feeling, by the way).

The steps I took were:

• Create an HA cluster with two servers
• Add an additional Virtual VMkernel NIC to handle FT traffic on each host
• Ensured that all hosts have access to multiple network storage devices (EMC and netapp).
• On a VM, changed the CPU/MMU Virtualization option to "Use Intel VT-x/AMD-V For Instruction set virtualization and software for MMU virtualization"
• Right-clicked on the VM and selected "turn On fault tolerance". This completed successfully.

Again, this worked.

Problem

Now, however, in the VM menu, after all hosts have come back on-line the option is again to "turn On Fault tolerance" (I thought once on, it would stay on?)

Additionally, if I click to turn fault tolerance on again, I receive the message "The virtual machine is running in a monitor mode that is incompatible for fault tolerance." However, selecting VT-x/AMD-V is what fixed this problem last time before my initial test that worked, and it is still selected in the menu.

Questions

• Is this a bug in the display, and the machine is still fault tolerant?
• Is this something I need to reconfigure each time?
• Once a machine has been configured for fault tolerance, does it remain in that mode perpetually? My guess would be that it should, but this experience makes me question it.

Update: More information (potential lead?)

To make matters more interesting, I just tried the following:

• Set CPU/MMU on the VM back to "Automatic"
• Rebooted the VM
• Set the CPU/MMU back to the intel setting that worked the first time
• Rebooted the VM
• Clicked "Turn Fault Tolerance on"
• ...and received the same error.

Thanks!

The answer in this case, both unfortunately and fortunately, appeared to be simple.

The error seems to be related to the fact that the VM was still powered on.

After powering off the VM, the fault tolerance option was able to be put in place.

In this case, VMWare appears to generate an error message that isn't very helpful.