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Which VM was this vSphere VM cloned from?

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This was a question that I saw back in December on the VMware {code} Slack which was quickly answered by the always awesome Luc Dekens. The solution is to look at vCenter Server Events, which are super rich in information and can be used for a number of things including identifying the source VM that it was cloned from. When I was a customer, this was something I did all the time, using events for auditing purposes but also identifying who, what and when a certain operation was performed including source VMs for cloning operations.

Although this information maybe known to some, there is still not an elegant solution that can help someone quickly identify the source VM for a specific vSphere VM that was cloned. This topic also intrigued me as I have seen this question come up in the past. I figure I might as well add this to my random scripting backlog and take a look when I had some time.

Before taking a look at the solution, it is important to understand the different types of clones that exists in vSphere today and also the respective vCenter Server events that can help us correlate to both the source VM but also the specific clone type.

Cloning Types

  • Full Clone - An independent copy of a virtual machine that shares nothing with the parent virtual machine after the cloning operation. Ongoing operation of a full clone is entirely separate from the parent virtual machine
  • Linked Clone - A copy of a virtual machine that shares virtual disks with the parent virtual machine in an ongoing manner. This conserves disk space, and allows multiple virtual machines to use the same software installation
  • Instant Clone - An independent copy of a virtual machine that starts executing from the exact running state of the source powered on virtual machine. Instant Clone uses rapid in-memory cloning of a running parent virtual machine and copy-on-write, simliar to that of Linked Cloning to rapidly deploy virtual machines

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Feedback on default behavior for VM Storage Policy

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Today, the vCenter REST (vSphere Automation) APIs currently does not support the use of VM Storage Policies when relocating (vMotion, Cross Datacenter vMotion & Storage vMotion) or cloning an existing Virtual Machine. Customers have provided feedback that this is something that they would like to see get added to the current REST APIs and while this is being looked at, there were a couple of open questions from Engineering.

The following 2-question survey below is to help us understand what the "default" behavior should be when a Virtual Machine is being relocated or cloned within a vCenter Server and a VM Storage Policy is NOT specified when using the APIs. The reason for this is that our existing APIs for relocate and clone today are very flexible and not everything needs to be specified as part of the relocate or clone API specification. However, due to this flexibility, you may observe different behaviors and we would like to understand what the default behavior should be when some of these paraemters are not specified. In the case where you want to be explicit, you can always specify the VM Storage Policy, but the survey is to understand when it is not specified.

Survey: https://goo.gl/forms/aQjVTly2MmVHeRsp1

Thank you  for taking the time to provide your feedback, this will help us build an easy and robust API when dealing with relocate and clone operations using the vCenter REST APIs.

How to properly clone a Nested ESXi VM?

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I often hear from users that they would like to be able to just clone from an existing Nested ESXi VM that has already been configured and just create additional Nested ESXi VM instances from that. For me personally, I do not have a use case for this since I just deploy additional ESXi instances using an automated Kickstart deployment. However, I can see why this would be useful for anyone that does not have an automated deployment or just want to quickly deploy additional Nested ESXi instances by just cloning from an existing image and then manually change the networking configuration afterwards.

UPDATE (07/01/21) - As of ESXi 7.0 Update 2, cloning an ESXi boot volume (Nested or Physical) is no longer safe and can lead to data corruption. Please refer to the following two VMware KB articles for more information on this topic https://kb.vmware.com/kb/84280 and https://kb.vmware.com/kb/84349 

First off, cloning of a Nested ESXi VM is possible and you can already do this today. You will get a brand new Virtual Machine that will have a unique MoRef ID, InstanceUUID, BIOS UUID and MAC Addresses for each of the virtual network adapters which you can see an example of this from the screenshot below.

Everything from outside of the guest OS looks great as we would expect but there is actually two issues from within ESXi that you may not be aware of.

  • The first issue is that you will get a duplicated MAC Address of the VMkernel interface(s) because the Nested ESXi configuration is exactly the same.
  • The second issue is having a duplicated ESXi System UUID, also known as a VMkernel UUID which should normally be unique and can sometimes be used for tracking purposes. You can see this System UUID by running the following ESXCLI command: esxcli system uuid get or by looking in esx.conf configuration file.

To properly clone an existing Nested ESXi VM, you will need to perform the following two operations within the Nested ESXi VM prior to cloning.

First Configuration - There is an advanced ESXi setting called FollowHardwareMac that will automatically update the VMkernel's MAC Address whenever the Virtual Machine's virtual network adapter MAC Addresses changes. To do so, you will need to run the following ESXCLI command:

esxcli system settings advanced set -o /Net/FollowHardwareMac -i 1

Second Configuration - The other modification that is required is to delete the existing System UUID entry in /etc/vmware/esx.conf configuration file. This will ensure a new System UUID will automatically be generated when the system boots up. To do so, open esx.conf and delete the entire /system/uuid line entry as seen in the screenshot below. Here is a quick snippet you can run without needing to open up VI:

sed -i 's#/system/uuid.*##' /etc/vmware/esx.conf

To ensure the file is persisted, run /sbin/auto-backup.sh

Once both configurations have been performed you are now ready to start cloning additional Nested ESXi instances. You will still need to login to each Nested ESXi VM and manually change the IP Address and hostname which you of course can leverage the Guest Operations API if you have VMware Tools for Nested ESXi installed.

If you plan on joining your "cloned" Nested ESXi instances to a vCenter Server and the ESXi hosts contains a local datastore, you will not be able to add the hosts to the same Datacenter/Cluster. The reason for this is that the cloned ESXi hosts will have a duplicated VMFS UUID. To fix this, you just need to re-signature the VMFS volume by using the following ESXCLI command:

esxcli storage vmfs snapshot resignature -l [VMFS-VOLUME]