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How to Enable Nested ESXi & Other Hypervisors in vCloud Director 5.1

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The process to enable  "Nested Virtualization" in the latest release of vCloud Director 5.1 and create your own virtual lab similar to VMware's vSEL (Virtual Sales Enablement Cloud) is very similar to the previous steps outlined for vCloud Director 1.5 release. The only change is how VHV (Virtual Hardware-Assisted Virtualization) aka "Nested Virtualization" is enabled in vCloud Director 5.1 and ESXi 5.1.

In the vCloud Director 1.5, to enable VHV, you needed to add a special SQL statement that would enable VHV for the underlying ESXi 5.0 hosts. With the latest release of vCloud Director 5.1, that is no longer necessary and you now enable it on a Per VM basis within the vCloud Director 5.1 UI.

Here are the steps for enabling VHV for vCloud Director 5.1

  • Insert SQL statements into VCD Database that perform the following:
    • Enable new "VMware" guestOS Family
    • Enable new guestOS Type ESXi 4.x and 5.x
    • Enable host preparation to enable VHV (vSphere 5.0 & vCloud 1.5 only)
  • Enable promiscuous mode
    • Insert SQL statement into VCD Database for Network Pool that is being used for your ESXi VMs
    • Enable both Promiscuous Mode and Forged Transmit for vSphere Backed Portgroup within vCenter Server or ESXi host

The SQL statements can be found in this article and have not changed for vCloud Director 5.1

Here is a screenshot of what you should see in the vCloud Director 5.1 UI for creating a new VM and you should now have the ability to select a new guestOS Type called "VMware" and select either an ESXi 4.x or ESXi 5.x guestOS Version.

To enable VHV for the VM, you will need to also check the box "Exposed hardware-assisted CPU virtualization to guestOS" and this will allow you to run a nested ESXi VM as well as 64-bit nested VMs, assuming your physical CPUs support it. To learn more about running VHV on ESXi 5.1, take a look at this article here for more details.

How to Enable Nested ESXi & Other Hypervisors in vSphere 5.1

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There are a ton of new features with the latest release of vSphere 5.1, but the one "unsupported" feature I always test first is "Nested Virtualization" (aka Nested ESXi) and with the latest release, it seems to have gotten even better. You will still need to have the same physical CPU prerequisites as you did in the past to run "Nested Virtualization" as well as nesting 64-bit VMs.

  • Intel VT-x or AMD-V is required for running "Nested Virtualization" which supports nested 32-bit VMs
  • Intel EPT or AMD RVI is required for running nested 64-bit VMs.

A quick way to verify whether your CPU truly supports both Intel-VT+EPT or AMD-V+RVI, you can paste the following into a browser:  

https://[your-esxi-host-ip-address]/mob/?moid=ha-host&doPath=capability

You will need to login with your root credentials and then look for the "nestedHVSupported" property and if it states false, it means you maybe able to install nested ESXi or other hypervisor, but you will not be able to run nested 64-bit VMs, only 32-bit VMs, assuming you have either Intel-VT or AMD-V support on your CPUs.

For more details, take a look at this article for troubleshooting: Having Difficulties Enabling Nested ESXi in vSphere 5.1?

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

There are some changes with Nested Virtualization in vSphere 5.1 also officially known as VHV (Virtual Hardware-Assisted Virtualization). If you are using vSphere 5.0 to run Nested ESXi or other nested Hypervisors, then please take a look at the instructions in this article. With vSphere 5.1, there have been a few minor changes to enable VHV.

  1. The new Virtual Hardware 9 compatibility will be required when creating your nested ESXi VM, Virtual Hardware 8 will not work if you are running ESXi 5.1 on your physical host. You will still need to enable promiscuous mode on the portgroup that will be used for your nested ESXi VM for network connectivity.
  2. vhv.allow = "true" is no longer valid for ESXi 5.1 to enable VHV. A new parameter has been introduced called vhv.enable = "true" that is now defined on a per VM basis to provide finer granularity of VHV support. This also allows for better portability between VMware's hosted products such as VMware Fusion and Workstation as they also support the vhv.enable parameter.
  3. You can now enable VHV on a per VM basis and using the new vSphere Web Client which basically adds the vhv.enable = "true" parameter to the VM's .VMX configuration file.

Note: You can run a nested ESXi 5.1 VM on top of a physical ESXi 5.0 host, just follow the instructions here.

Enabling VHV (Virtual Hardware-Assisted Virtualization)

Step 1 - Create a new Virtual Hardware 9 Virtual Machine using the new vSphere Web Client that's available with vCenter Server 5.1.

Step 2 - Select "Linux" as the guestOS Family and "Other Linux (64-bit)" as the guestOS Version.

Step 3 - During the customize hardware wizard, expand the "CPU" section and select "Hardware Virtualization" box to enable VHV.

Note: If this box is grayed out, it means that your physical CPU does not supported Intel VT-x + EPT or AMD-V + RVI which is required to run VHV OR that you are not using Virtual Hardware 9. If your CPU only supports Intel-VT or AMD-V, then you can still install nested ESXi, but you will only be able to run nested 32-bit VMs and not nested 64-bit VMs.

Step 4 - It is still recommended that you change the guestOS Version to VMware ESXi 5.x after you have created the VM shell, as there are some special settings that are applied automatically. Unfortunately with the new vSphere Web Client, you will not be able to modify the guestOS after creation, so you will need to use the C# Client OR manually go into the .VMX and update guestOS = "vmkernel5"

Now you are ready to install nested ESXi VMs as well as run nested 64-bit VMs within.

If you have followed my previous article about How to Enable Support for Nested 64bit & Hyper-V VMs in vSphere 5 you may recall a diagram about the levels of "Inception" that can be performed with nested ESXi. That is, the number of times you could nest ESXi and still have it be in a "functional" state. With vSphere 5.0, the limit that I was able to push was 2 levels of nested ESXi. With latest release of vSphere 5.1, I have been able to push that limit now to an extraordinary 3 levels of inception!

You might ask why would someone want to do this ... well I don't have a good answer other than ... because I can? 😉 VHV is one of the coolest "unsupported" feature in my books and I'm glad it is working beyond what it was designed for.

For proper networking connectivity, also ensure that either your standard vSwitch or Distributed Virtual Switch has both promiscuous mode and forged transmit enabled either globally on the portgroup or distributed portgroup your nested ESXi hosts are connected to.

Nesting "Other" Hypervisors

For those of you who feel inclined to run other hypervisors such as Hyper-V, you can do so with latest release of ESXi 5.1. The process if very straight forward just like running nested ESXi host.

Step 1 - Create a Virtual Hardware 9 VM and select the appropriate guestOS. In this example, I selected Windows Server 2012 (64-bit) as the guestOS version.

Step 2 - Enable VHV under the CPU section if you wish to create and run nested 64-bit VMs under Hyper-V

Step 3 - You will need to add one additional .vmx parameter which tells the underlying guestOS (Hyper-V) that it is not running as a virtual guest which in fact it really is. The parameter is hypervisor.cpuid.v0 = FALSE

How to Enable Support for Nested 64bit & Hyper-V VMs in vSphere 5

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With the release of vSphere 5, one of the most sought out feature from VMware is the ability to run nested 64bit and Hyper-V guest virtual machines in a virtual ESXi instance. Previous to this, only 32bit virtual machines were supported as the VT-x/AMD-V Hardware Virtualization CPU instructions could not be virtualized and presented to the virtual ESX(i) guest. This feature is quite useful for home and lab setups in testing new features or studying for VMware certifications and running multiple vESX(i) instances.

You will still be required to have a 64bit capable system and CPU and you will need to be running ESXi 5.0, this will not work for ESX(i) 4.x or older.

The above diagram depicts the various levels of inception where pESXi is your physical ESXi 5.0 hosts. We then create a vESXi 5.0 host which will contain the necessary Hardware Virtualization CPU instructions to support a 64bit nested guest OS which I've created as another ESXi host called vvESXi.
Note: You will not be able to run a 4th level nested 64bit VM (I have tried by further passing the HV instructions in the nested guest) and it will just boot up and spin your CPUs for hours.
This feature by default is disabled in ESXi 5.0, to enable this virtualized HV (Hardware Virtualization) you will need to add the following string vhv.allow = "TRUE"  to /etc/vmware/config of your Physical ESXi 5.0 host
Once the configuration change has been made, the feature goes into effect right away. A reboot of the system is not necessary. To verify, you should now be able to power on a 64bit guest OS and see that the HV instructions bits are being passed into the guestOS which will then allow you to run a nested 64bit guestOS. You can also verify by looking in the vmware.log file of the virtual machine and grep for the string "monitorControl.vhv" and if you see the following message, then Virtualized HV is not enabled.
In the past to run a virtual ESX(i) instance, a few advanced .vmx configuration entries were needed as documented here. With ESXi 5.0, if you are using virtual hardware version 8, then you do not need to make any additional changes. If you are using hardware version 4 or 7, then you will need to add a few changes to the VM's configuration file.
Creating vESXi 5.0 Instance using Hardware Version 8:
1. To create a virtual ESXi 5.0 instance, start off by just creating a standard RHEL5/6 64bit VM using the vSphere Client
2. Once the VM has been created, edit the settings of the VM and change over to the "Options" and now have the ability to select a new guestOS type: VMware ESXi 5.x or VMware ESXi 4.x under the "Other" section.

Note: I'm not sure why these two additional guestOS type is not available from the default creation menu, but are available after the initial VM shell is created.

3. You are now ready to install ESXi 5.0 in this new vESXi host and then you can create and power on nested 64bit guestOS within that vESXi instance as denoted from the picture below

Creating vESXi 5.0 Instance using Hardware Version 4/7:
1. To create a virtual ESXi 5.0 instance, start off by just creating a standard RHEL5/6 64bit VM using the vSphere Client

2. Now you will need to add the following advanced .vmx parameter:  monitor.virtual_exec = "hardware" which can be done through the vSphere Client and/or editing the .vmx parameter manually.

3. Next you will need to add some cpuid bits, depending if you are running an Intel or AMD CPU, the respective entries are required:

Intel Hosts:

cpuid.1.ecx = "----:----:----:----:----:----:--h-:----"

AMD Hosts:

cpuid.80000001.ecx.amd = "----:----:----:----:----:----:----:-h--"
cpuid.8000000a.eax.amd = "hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh"
cpuid.8000000a.ebx.amd = "hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh"
cpuid.8000000a.edx.amd = "hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh"

4. You are now ready to install ESXi 5.0 in this new vESXi host and then you can create and power on nested 64bit guestOS within that vESXi instance

By using a VM that is hardware version 8, you can easily automate the creation of vESXi 5.0 instance by changing the guestOS string in the .vmx parameter to "vmkernel" and the above configurations other than "vhv" string needed for either an Intel or AMD system are automatically configured.

For proper networking connectivity, also ensure that either your standard vSwitch or Distributed Virtual Switch has both promiscuous mode and forged transmit enabled either globally on the portgroup or distributed portgroup your nested ESXi hosts are connected to.  

Creating a vHyper-V  Instance on physical ESXi 5.0:
1. To create a virtual Hyper-V instance, start off by creating a Windows 2008 Server R2 64bit VM using the vSphere Client

2. If you are using Hardware Version 7, you will need to follow the instructions in "Creating vESXi 5.0 Instance using Hardware Version 4/7" to add the additional parameters to the VM. If you are using Hardware Version 8, you just need to change the guestOS type to VMware ESXi 5.0

3. You need to add one additional .vmx parameter which tells the underlying guestOS (Hyper-V) that it is not running as a virtual guest which in fact it really is. The parameter is hypervisor.cpuid.v0 = FALSE

4. You are now ready to install Hyper-V in a virtual machine and you can also spin up nested 64bit guestOSes in this virtual Hyper-V instance.

As you can see, now you can even run Hyper-Crap, err I mean Hyper-V as a virtualized guest under ESXi 5.0. I did not get a chance to try out Xen, but I'm sure with the ability to virtualize the Hardware Virtualization instructions, you should be able to run other types of hypervisors for testing purposes.

This is a really awesome feature but note that this is not officially supported by VMware, use at your own risk.