Nested ESXi

Simplified Nested ESXi installation in ESXi 7.0 Update 2 using HTTP Boot over VirtualEFI

03/22/2021 by William Lam 17 Comments

Deploying an ESXi scripted installation aka Kickstart running within a VM (Nested ESXi) has a number of benefits, especially for testing and development purposes. This was something I did regularly as a customer, especially with new releases of ESXi to ensure our existing automation scripts and processes continued to work before rolling out into production. ESXi kickstart itself is pretty straight forward, but the required supporting infrastructure (PXE Server, DHCP, TFTP, etc) that needs to be configured, especially for a greenfield deployment can often be challenging for new comers.

Even with an existing PXE infrastructure, it can often be difficult to configure or troubleshoot depending on your level of access which does not add any value in actually testing or automating the ESXi scripted installation process. In ESXi 7.0 Update 2, an enhancement was made to the Virtual Machine's UEFI firmware called VirtualEFI that would enable ESXi to perform an HTTP Boot given the ESXi bootloader URL and without requiring any of the traditional PXE infrastructure.

To take advantage of this new capability, you just need to have a physical server running ESXi 7.0 Update 2 and a VM that is configured with the latest vHW19 compatibility. To configure HTTP boot, you will need to add the following two VM Advanced Settings:

networkBootProtocol - httpv4 or httpv6
networkBootUri - HTTP URL to the ESXi bootloader (bootx64.efi)

Disclaimer: Nested ESXi and Nested Virtualization is not officially supported by VMware

Heads Up – Nested ESXi crashes in ESXi 7.0 running on older CPUs

04/17/2020 by William Lam 27 Comments

Thanks to Patrik Kernstock, who works in our Technical Support organization at VMware, for making me aware of an issue related to Nested ESXi running on an ESXi host that has been upgraded to ESXi 7.0. Several folks in the community have noticed after upgrading their Intel NUC 7th Gen and deploying a Nested ESXi VM and powering on an inner-guestOS would causes the Nested ESXi VM to crash.

Upon further investigation, it looks like this is not specific to the Intel NUC platform but rather with a specific generation of CPUs which are Intel Sky Lake-based and as a result, some customers are noticing this affect on their 7th Gen NUC.

UPDATE (06/23/20) - ESXi 7.0b has just been released and contains the fix for the Nested ESXi VM crash. If you are using an Intel NUC 10, do not just apply the patch as the updated ne1000 VIB within the patch will override existing Intel NIC driver causing the network adapter to no longer function. It is recommended that you download the patch and replace the default ne1000 VIB using Image Builder with the Intel NIC version before applying the update. To download the patch, please visit VMware Patch Portal site.

The good news is that this issue has already been reported and we should have a fix in a future update of ESXi. In the meantime, you can still run Nested ESXi and Nested Virtualization on these affected CPUs, you just will not be able to power on inner-guest VMs. Big thanks to Patrik for helping out with the testing and triaging this internally.

Running Nested ESXi, NSX-V or NSX-T on top of NSX-T

11/22/2019 by William Lam 6 Comments

Nested Virtualization is an extremely useful tool that helps customers easily test and try out new VMware products and solutions before rolling that into a proper development environment for further validation. This is especially handy for those wanting to setup an NSX-based environment and simulating their actual deployment topology, configuration and upgrade workflows.

In this past year, I have seen a 10x increase in the number of NSX-T based questions that have come up from customers and our field, the adoption of NSX-T is definitely in full swing. As expected, questions about running Nested ESXi on top of a physical NSX-T deployment has come up and there has actually been several variations that have been asked about whether that is Nested ESXi using VSS, VDS, NSX-V or even NSX-T running on top of an N-VDS, which is the virtual switch that NSX-T uses.

Luckily all of these combinations work and just require some basic configuration changes within NSX-T. However, before I continue, let me remind folks again that VMware does NOT officially support Nested Virtualization.

ESX 3.x on VMware Cloud on AWS?

10/10/2019 by William Lam 2 Comments

VMworld Barcelona is just around the corner and this week I started working on building out the different demo environments which will all be running on VMware Cloud on AWS. In one of the demos, I need to have ESX 3.0 running, yes you read that correctly! ESX as in the original version with the Service Console (cos), some of you maybe too young to remember these good ol days? 😉

First, Let me be clear, there really is no good reason for this except for the nostalgia purposes and for what I am trying to demonstrate in our VMworld session. If you are curious about the demo and attend VMworld, be sure to sign up for HBI1967BE Workload Migration Techniques for On-Premises and Cloud Infrastructures which I will be co-presenting with Emad Younis. Secondly, Nested Virtualization whether it is the latest version of ESXi or our very first release, is not officially supported.

Nested ESXi on VMware Cloud on AWS (VMC)

09/28/2018 by William Lam 5 Comments

I have had a few folks ask about Nested ESXi support on VMware Cloud on AWS (VMC), so lets get that out of the way first. Nested ESXi is NOT supported by VMware on any of our platforms, whether that is an on-premises or a cloud environment like VMC or any 3rd party vendors that maybe using VMware software. For those wanting an "official" statement on Nested ESXi support, you can refer to KB 2009916.

UPDATE (02/10/20) - Updated my Automated vSphere Lab Deployment Script to support "basic" Nested vSphere environment running on VMC.

Was asked if it was possible to setup a “basic” Nested vSphere environment for Automation/API testing running in #VMWonAWS

Just updated my Automated vSphere Deployment Lab Script https://t.co/50tJmcDcH2 to enable support for #VMC 😊 pic.twitter.com/n0SeNIaJm8

— William Lam (@lamw) February 10, 2020

Now, we all know Nested ESXi works and it runs extremely well on vSphere. In fact, vSphere is the best platform for running any Hypervisor in a VM. This is also true for VMC, you can run a Nested ESXi VM in an SDDC, however there are some caveats compared to what you would experience in an on-prem environment. Below are some of the caveats to be aware of if you are considering running Nested ESXi on VMC.

How to simulate Persistent Memory (PMem) in vSphere 6.7 for educational purposes?

05/24/2018 by William Lam 4 Comments

A really cool new capability that was introduced in vSphere 6.7 is the support for the extremely fast memory technology known as non-volatile memory (NVM), also known as persistent memory (PMem). Customers can now benefit from the high data transfer rate of volatile memory with the persistence and resiliency of traditional storage. As of this blog post, both Dell and HP have Persistent Memory support and you can see the list of supported devices and systems here and here.

PMem can be consumed in one of two methods:

Virtual PMem (vPMem) - In this mode, the GuestOS is actually PMem-aware and can consume the physical PMem device on the ESXi host as standard, byte-addressable memory. In addition to using an OS that supports PMem, you will also need to ensure that the VM is running the latest Virtual Hardware 14
Virtual PMem Disks (vPMemDisk) - In this mode, the GuestOS is NOT PMem-aware and does not have access to the physical PMem device. Instead, a new virtual PMem hard disk can be created and attached to a VM. To ensure the PMem hard disk is placed on the PMem Datastore as part of this workflow, a new PMem VM Storage Policy will be applied automatically. There are no additional GuestOS or VM Virtual Hardware requirement for this scenario, this is great for legacy OS that are not PMem-aware

Customers who may want to familiarize themselves with these new PMem workflows, especially for Automation or educational purposes, could definitely benefit from the ability to simulate PMem in their vSphere environment prior to obtaining a physical PMem device. Fortunately, this is something you can actually do if you have some additional spare memory from your physical ESXi host.

Disclaimer: This is not officially supported by VMware. Unlike a real physical PMem device where your data will be persisted upon a reboot, the simulated method will NOT persist your data. Please use this at your own risk and do not place important or critical VMs using this method.