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VSAN Managed Object Browser (MOB) in vSphere 6.7 & vSphere 6.7 Update 1

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If you have ever spent any time using the vSphere API, you probably have heard of or have used the vSphere Managed Objected Browser (MOB) which is an extremely useful learning and debugging tool when working with the vSphere API. The vSphere MOB is accessed through a web browser connecting to either vCenter Server or ESXi and provides a graphical interface, allowing you to discovery/explore the underlying vSphere API and its data in a very intuitive manner.

As an avid user of the VSAN Management API since its release, I have always wanted something similar, especially when I first got started. I was quite happy when I found out in vSphere 6.7 and VSAN 6.7, the VSAN team has added a VSAN MOB interface directly on ESXi, for the VSAN specific APIs that are available only on an ESXi host. Just like the vSphere MOB which is also available on ESXi host, it is disabled by default and must be enabled.

The following ESXCLI commands can be used to enable/disable the VSAN MOB on ESXi 6.7:

esxcli vsan debug mob start
esxcli vsan debug mob stop

However, when I tried to enable the VSAN MOB, I ran into the following error message:

hostname 'localhost.localdomain' doesn't match '192.168.30.10'


It turns out there is an issue where it fails to match the IP Address of the ESXi host to the default localhost.localdomain and hence it fails to start the VSAN MOB. This issue is fixed in the upcoming vSphere & VSAN 6.7 Update 1, but in the mean time, there is a workaround.

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Retrieving detailed per-VM space utilization on VSAN

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I was recently helping out my friend Paudie O'Riordan with a request from a customer who was looking for a way to collect detailed space utilization for their VMs (VM Home, VMDK & swap) running on VSAN. Today, this level of granularity is not available in the vSphere UI and the customer was interested in both the used and reserved capacity on a per-VM basis. Luckily, this information can be retrieved using the VSAN Management API.

To do so, we just need to use the VsanQueryObjectIdentities() API method, which I have used in the past to retrieve things like "thick" provisioned VM and translating VSAN Object IDs to their friendly VM display name. To retrieve space utilization information, we just need to set the includeSpaceSummary property to be true. While developing the PowerCLI sample script, I found that this specific property is currently not supported when querying vCenter Server and to retrieve this information, you must go directly to each ESXi host within the VSAN Cluster. I have already filed a feature request and it looks like this will be fixed in a future vSphere release.

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Leveraging Instant Clone in vSphere 6.7 for extremely fast Nested ESXi provisioning

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The idea of "Instant Cloning" a Nested ESXi VM (running ESXi in a VM) is not a new concept. In fact, I had shared a solution back in 2015 using the private VMFork APIs. However, what has changed is the ease of consumption, primarily due to the re-architecture of Instant Clone in vSphere 6.7 (more details here and here) which resulted in a public and simplified API. Some of you might ask, why not simply clone a Nested ESXi VM or create a Link Clone? What benefit would I get by using Instant Clone?

The answer is not only speed, but the fact that the instantiated VM is fully operational and ready to start executing where as a traditional full clone or linked clone requires a full OS boot up that can take up to several minutes to deploy and configure. This may not sound like much for a small number of Nested ESXi VMs, but as you increase the number of instances, Instant Clone really shines while still maintaining speed and the instant availability of the VM. As you can imagine, this definitely opens up for some interesting use cases whether it be for personal home lab or educational purposes like VMware HOL. In addition, we also have customers who deploy Nested ESXi not only at high scale but also with a high churn rate for development purposes, think CI/CD type of a workload who can also benefit from Instant Clone.

So how fast are we talking about? Lets say you wanted to test out the latest version of VSAN in vSphere 6.7, you would normally deploy 3 Nested ESXi VMs, power them up and wait for them to be ready on the network. With Instant Clone, you can deploy three fully functional Nested ESXi VMs in just 30seconds! As the VMs are instantly available for consumption, you can start the VSAN enablement workflow immediately and even parts of that can be baked into the Instant Clone workflow. With the ease of provisioning Nested ESXi VMs, you can simply maintain a catalog of ESXi templates which are in "frozen" states and then leverage Instant Clone to deploy just-in-time Nested ESXi environments and discard them once you are done. Pretty slick if you ask me! and something I plan on using going forward.

Disclaimer: Nested ESXi is still not officially supported by VMware. Please use at your own risk.

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