April 27, 2016

VMFork using mob

We cannot do VMFork without PowerCLI Extension for now. But that means there are VMFork related APIs in vSphere API.

I explored those APIs using the MOB(The Managed Object Browser). Then I found it and I understand how to use it.

Disclaimer: VMFork is not officially supported by VMware, please use at your own risk.

There are following methods in VirtualMachine object.

  • CreateForkChild_Task
  • EnableForkParent_Task
  • DisableForkParent_Task
  • RetrieveForkChildren_Task
  • RetrieveForkParent_Task

Also, there are config.forkconfiginfo and runtime.quiescedforkparent in VirtualMachine properties.

These methods and properties are found in the HTML source of VM page on the MOB.

This time, we want to run the VMFork, so we use EnableForkParent_Task and CreateForkChild_Task.

How to run the VMFork using the MOB.

1. Open the MOB.


2. Open the VirtualMachine you want to use as parent VM.

Open the parent VM with using rootFolder or searchIndex. The URL would be like here.


3. Run EnableForkParent_Task

Open following URL.


This method has no parameters, you have only to click Invoke Method.

4. Quiesce the parent VM

Run this command on the parent VM via console or SSH.

vmtoolsd --cmd 'vmfork-begin -1 -1'

If you want to automate it, you can use GuestOperationsManager.ProcessManager.

PowerCLI’s Enable-InstantCloneVM upload PreQuiesceScript and PostCloneScript with operations up to this point.

You can upload these scripts with GuestOperationsManager instead of PowerCLI.

Also, It seems that PowerCLI’s Enable-InstantCloneVM runs PreQuiesceScript and PostCloneScript with GuestOperationsManager. The command is like here.

$prescript_path;vmtoolsd --cmd 'vmfork-begin -1 -1';$postscript_path

5. Run VMFork

Use CreateForkChild_Task. It is same as PowerCLI’s New-InstantCloneVM. The URL is following.


CreateForkChild_Task has parameters, name and spec. name is child VM name. And I guess spec is VirtualMachineCreateChildSpec. Minimun spec is here.


Click Invoke Method. The child VM will be created in an instant.


© Yuya Kusakabe 2011-2022

Powered by Hugo & Kiss.