Search Results for: nested esxi

How to run Qemu & KVM on ESXi?

09.17.2014 by William Lam // 4 Comments

Last week I was asked whether ESXi could run the KVM hypervisor as a Virtual Machine (often referred to as Nested Virtualization). I personally have not used KVM before or run it on top of ESXi, but I have heard of many folks successfully virtualizing KVM as a Virtual Machine on top of ESXi. I figure since I have already written several articles on Nesting VMware ESXi, Microsoft Hyper-V and Xen on top of ESXi, I might as well also take a look at KVM!

Disclaimer: Nested Virtualization is not supported by VMware, please use at your own risk.

As mentioned already, I have not used KVM before and one thing I wanted to understand before trying to run it as a Virtual Machine is what the difference is between Qemu and KVM as I have heard both these terms used in-conjunction before. I found this post to be quite helpful in helping me understand the differences between Qemu, KQemu and KVM. I recommend a read if you are new to Qemu or KVM like I am.

From the article above, we now see that you can run either Qemu as a standalone system or KVM which is an accelerator that runs on top of Qemu. With this, I will now demonstrate how you can run Qemu as well as KVM as Virtual Machine on top of ESXi. In the example below, I have selected the latest Ubuntu release (14.04.1) to run both Qemu and KVM.

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Quick Tip - How to snapshot & revert a physical ESXi host

04.04.2014 by William Lam // 5 Comments

Nested environment, which is something I did quite a bit of as a customer and still continue to do so today. I could easily snapshot my Nested ESXi environment, perform my tests and then quickly rollback to my original starting state. However, when it comes to testing a physical ESXi host, it is a bit more challenging as there is no "quick" snapshot functionality as far as I was aware of. It was only until recently did I have a use case for this and picked up a nice tidbit from one of our engineers on the team. It turns out you could "snapshot" a physical or even virtual ESXi host by just backing up the state.tgz file and then restoring it. As the name suggest, the state.tgz file contains all the configurations of your ESXi host. The process is pretty straight forward:

SCP /bootbank/state.tgz and back that up to your local system or shared storage
Perform your tests or make changes to the system
When you are ready to restore, copy the state.tgz back into /bootbank folder
Login to ESXi Shell and run reboot -f which will ensure no changes are saved to our state.tgz

Once the ESXi host reboots, it will use the restored state.tgz file and your system will be back at its original state. This process is actually not new, ESXi already provides a way to backup/restore

Quick Tip - Increasing capacity on a Nested VSAN Datastore

03.21.2014 by William Lam // 2 Comments

The other day I needed to increase the capacity on one of my Nested VSAN Datastores as one of our users required a larger VSAN datastore than it was initially configured for. I was expecting to be able to just increase the size of the underlying VMDKs like I would for a traditional Nested ESXi environment and rescan in ESXi to pick up the new capacity without any downtime. It turns out, this is was not exactly the case for a Nested VSAN environment.

Disclaimer: Nested Virtualization is not officially supported by VMware

When you first setup VSAN, regardless of how the disks were claimed, VSAN will consume the entire device (SSD or MD). The capacity that VSAN initially detects will then be used to create the necessary partition as part of the VSAN Disk Group creation. VSAN assumes that the capacity for the underlying devices would never change as in the "real" world, disks do not auto-magically get larger 🙂 and this is a valid assumption. In a Nested ESXi environment however, it can auto-magically get larger but VSAN was not built for this use case. What ends up happening is that the underlying devices can be "hot-extended" but the existing VSAN Disk Group can not detect this new capacity.

Having said that, there are two ways you can increase your VSAN datastore:

Option 1 - If you wish to preserve your VSAN Datastore, you can hot-add additional VMDK(s) to your existing VSAN Disk Group or if it is full, you can create a new disk group and add additional VMDK(s). This will modify your setup slightly if you wanted a particular set of disk groups but will allow you to preserve your data.

Option 2 - The latter option requires the deletion and re-creation of the VSAN Datastore which is not ideal if you already have data on it. You will need to increase the capacity of the underlying VMDKs and then re-create your VSAN Datastore, but this way you can keep the existing number of disks and disk groups you initially created your Nested ESXi environment with.

In my scenario, I could not destroy the VSAN Datastore as I had someone using it and so I opted for option #1. Here is what my configuration looked like before which was a single VSAN Disk Group with 1xSSD and 1xMD:

I then added an additional 10GB VMDK to each of my Nested ESXi hosts and issue a rescan so the ESXi host would pickup the new device:

In just a few seconds, I can see my new storage device. I can now head over to the VSAN management page which is located at the vSphere Cluster and once I refresh, I can see that VSAN has automatically added the new "MD" into the existing disk group and my storage has automatically expanded!