• Cloning a Virtual Machine (VM) in ESXi without using VMware vSphere doesn't work because in the vSphere Client, which can be also used to manage the ESXi, you have no possibility to do this.

• Using the free version of VMware-Converter is possible but slow.
• There is a possibility to clone a virtual disk by using the command line of the ESXi.
• You need to have a VM which you could use as template.

• First read completely

1. If you hadn't activate SSH then do this as described here.
2. Create a new VM with the same configuration as the machine you wish to clone.
3. By creating the VM you also created its virtual disk (*.vmdk).
4. Delete this disk (we will replace it with the clone) by using the “Datastore Browser” or SSH on ESXi.
5. Connect to your ESXi by using SSH.
6. type the following command (here “ubu-10.04-server” is the template).

vmkfstools -i /vmfs/volumes/datastore1/ubu-10.04-server/ubu-10.04-server.vmdk /vmfs/volumes/datastore1/newmachine/newmachine.vmdk
Destination disk format: VMFS zeroedthick
Cloning disk '/vmfs/volumes/datastore1/ubu-10.04-server/ubu-10.04-server.vmdk'...
Clone: 100% done.

• boot your new machine and configure it.