Yes, as the title says, a VMware ESX can be virtualized 4.0 inside another VMware VM, and also, be able to create and boot virtual machines within our virtual VMware ESX!!! Logically we are talking about a test environment and never for production, as it is ideal for setting up your own lab if you don't have enough VMware ESX-compatible hardware 4.0 and want to try out the new features (Fault Tolerance or FT, vNetwork Distributed Switch or DVS, Host Profiles Linked VC… Let's go vSphere) or if you want to perform a testing lab… it is also done in a few very simple and quick steps.

I am doing this example from a VMware ESX 4, I will create a virtual machine on it to later install another VMware ESX 4.0 inside it. I believe it is a requirement that the physical machine to be virtualized is VMware ESX 4, and not an ESX 3.5 or any other edition of VMware in order to later run virtual machines inside the ESX virtual machine. What a mess 😉

So we create a new virtual machine from ESX, “New Virtual Machine…”

We select configuration “Typical”, “Next”,

We give a name to this new virtual ESX server, “Next”,

We select our datastore or storage where we will keep this virtual machine, “Next”

We select the operating system “Linux” & “Red Hat Enterprise Linux 5 (64-bit)” & “Next”,

We specify a size for our disk, “Next”,

We mark the check of “Edit the virtual machine settings before completion” & “Continue”,

Tenemos que cambiarle la memoria RAM y darle como mínimo 2Gb.

Apart from, Let's go to the tab “Options”, “Advanced” > “General” y pulsamos en botón “Configuration Parameters…”

Tenemos que crear un nuevo parámetro de configuración si queremos que este servidor pueda ejecutar máquinas virtuales dentro de él, To do this, click on “Add Row” y escribimos en ‘Name’ el dato ‘monitor_control.restrict_backdoor’ y en la columna ‘Value’ ponemos ‘true’. Damos a OK a todo,

Now, sobre el switch al que queramos conectar nuesta máquina virtual de ESX, vamos donde tengamos sus adaptadores de red virtuales conectados. On the “Configuration” > “Networking” Click on “Propierties…” del switch.

Sobre nuestro vSwitch pulsamos en “Edit…”

Y configuramos el “Promiscuos Mode” para que acepte los paquetes y podamos conectarnos a nuestro servidor interno, as well as their MV’s. “OK”,

Accept,

We installed the VMware ESX server in the traditional way, we insert the DVD or use an ISO, if you don't know how, here you have a document on how to install VMware ESX 4.0 (http://www.bujarra.com/?p=2530). Once installed, we will see that we can connect to it with the VMware client (VMware vSphere Client) and create virtual machines inside and start them. This image is amazing, ¿No? Here we have an example!

And also, if we want to enable FT (Fault Tolerance) with the virtual machines of the ESX virtuals, we will edit the .vmx files of each virtual machine to be protected and add a line indicating:

replay.allowBTOnly = TRUE