Running VMware ESX 4 inside VMware Workstation 6.x.

There are lot of posts which describe how to install VMware ESX inside a VMware workstation, for eg: http://vmblog.com/archive/2007/11/01/more-on-installing-vmware-esx-server-inside-a-workstation-6-vm.aspx

This is easy and can be done very quickly. The next step of course is to create a VM. In my test bed I tried to install a RHEL4 OS inside VMware ESX using vCenter. I could create the VM very easily using the Create New Virtual Machine wizard however, the VM wouldn't power ON!. When you try to power the VM ON, the error that it would throw is

"you may not power on a virtual machine inside a virtual machine"

The reason why this happens is that when you installed VMware ESX inside a virtualized environment, you chose to install it as a "Red Hat Enterprise Linux 5" OS. As a result the VMware virtual machine configuration file stores parameter guestOS as follows:

guestOS = "RHEL5"


What you have to do is, edit the VMware virtual machine configuration file (.vmx file inside the folder where you've created the ESX VM) using notepad/wordpad and change it to:

guestOS = "vmkernel"

Now, power ON the OS and voila, it boots. Connect it to your installation CD/ISO and install the system!