Search Results for: nested esxi

How to tell if an ESXi host is a VSAN Witness Virtual Appliance programmatically?

09.26.2016 by William Lam // Leave a Comment

I had received this question awhile back but I was only able to get to it recently. If you are not familiar with the VSAN Witness Virtual Appliance and its purpose, Cormac Hogan did an excellent write-up on the topic which you can find it here.

The reason this question came up was that if you were to simply iterate over all ESXi hosts within your vSphere Inventory from an Automation standpoint, you might find a mix of regular ESXi hosts and potentially this new VSAN Witness Virtual Appliance which is basically an ESXi host that runs in a VM (e.g. Nested ESXi). Although, it may look and feel like a regular ESXi host, it is not and the question was how might you go about distinguishing between the two? You can of course setup specific naming standards, folder structure or separate datacenter objects, but you still may accidentally retrieve a VSAN Witness host without even realizing it.

One quick solution is to check for a specific ESXi Advanced Setting called Misc.vsanWitnessVirtualAppliance which will return a value of 1 if it is the VSAN Witness Appliance. Here is a quick PowerCLI snippet which demonstrates how you can access this property:

$vmhost = Get-VMHost -Name 192.168.1.115
Get-AdvancedSetting -Entity $vmhost -Name Misc.vsanWitnessVirtualAppliance

Although the method described above is one quick way to easily identify whether an ESXi host is a VSAN Witness Appliance, it is also limited in the information that it provides you. Another approach is to actually use the new VSAN 6.2 Management API and specifically the Stretched Clustering System APIs to retrieve the associated VSAN Witness host for a given VSAN Cluster. Not only will you get more information about the specific ESXi host providing the VSAN Witness functionality which will allow you to correlate back to your vSphere Inventory, but you will also get additional VSAN Witness configuration such as the preferred Fault Domain, Node UUID and the VSAN Cluster that it is associated with for example.

Here is a quick VSAN Management SDK for Python sample script that I had created called vsan-stretched-cluster-system-sample.py which implements the VSANVcGetWitnessHosts() API method. The script prints out a few of the WitnessHostInfo properties as shown in the screenshot below.

One other option is if you simply just want to know if a given ESXI host is a VSAN Witness host or not, there is also the VSANVcIsWitnessHost() API that simply returns a boolean value. This might useful if you just have a list of ESXi hosts retrieved through the vSphere API and no knowledge of the underlying VSAN Clusters.

Migrating ESXi to a Distributed Virtual Switch with a single NIC running vCenter Server

11.18.2015 by William Lam // 29 Comments

Earlier this week I needed test something which required a VMware Distributed Virtual Switch (VDS) and this had to be a physical setup, so Nested ESXi was out of the question. I could have used my remote lab, but given what I was testing was a bit "experimental", I prefered using my home lab in the event I need direct console access. At home, I run ESXi on a single Apple Mac Mini and one of the challenges with this and other similar platforms (e.g. Intel NUC) is that they only have a single network interface. As you might have guessed, this is a problem when looking to migrate from a Virtual Standard Switch (VSS) to VDS, as it requires at least two NICS.

Unfortunately, I had no other choice and needed to find a solution. After a couple minutes of searching around the web, I stumbled across this serverfault thread here which provided a partial solution to my problem. In vSphere 5.1, we introduced a new feature which would automatically roll back a network configuration change if it negatively impacted network connectivity to your vCenter Server. This feature could be disabled temporarily by editing the vCenter Server Advanced Setting (config.vpxd.network.rollback) which would allow us to by-pass the single NIC issue, however this does not solve the problem entirely. What ends up happening is that the single pNIC is now associated with the VDS, but the VM portgroups are not migrated and the reason that this is problematic is that the vCenter Server is also running on the ESXi host which it is managing and has now lost network connectivity 🙂

I lost access to my vCenter Server and even though I could connect directly to the ESXi host, I was not able to change the VM Network to the Distributed Virtual Portgroup (DVPG). This is actually an expected behavior and there is an easy work around, let me explain. When you create a DVPG, there are three different bindings: Static, Dynamic, and Ephemeral that can be configured and by default, Static binding is used. Both Static and Dynamic DVPGs can only be managed through vCenter Server and because of this, you can not change the VM network to a non-Ephemeral DVPG and in fact, it is not even listed when connecting to the vSphere C# Client. The simple work around is to create a DVPG using the Ephemeral binding and this will allow you to then change the VM network of your vCenter Server and is the last piece to solving this puzzle.

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

Here are the exact steps to take if you wish to migrate an ESXi host with a single NIC from a VSS to VDS and running vCenter Server:

Step 1 - Change the following vCenter Server Advanced Setting config.vpxd.network.rollback to false:

Note: Remember to re-enable this feature once you have completed the migration

Step 2 - Create a new VDS and the associated Portgroups for both your VMkernel interfaces and VM Networks. For the DVPG which will be used for the vCenter Server's VM network, be sure to change the binding to Ephemeral before proceeding with the VDS migration.

Step 3 - Proceed with the normal VDS Migration wizard using the vSphere Web/C# Client and ensure that you perform the correct mappings. Once completed, you should now be able connect directly to the ESXi host using either the vSphere C# Client or ESXi Embedded Host Client to confirm that the VDS migration was successful as seen in the screenshot below.

Note: If you forgot to perform Step 2 (which I initially did), you will need to login to the DCUI of your ESXi host and restore the networking configurations.

Step 4 - The last and final step is to change the VM network for your vCenter Server. In my case, I am using the VCSA and due to a bug I found in the Embedded Host Client, you will need to use the vSphere C# Client to perform this change if you are running VCSA 6.x. If you are running Windows VC or VCSA 5.x, then you can use the Embedded Host Client to modify the VM network to use the new DVPG.

Once you have completed the VM reconfiguration you should now be able to login to your vCenter Server which is now connected to a DVPG running on a VDS which is backed by a single NIC on your ESXi host 😀

There is probably no good use case for this outside of home labs, but I was happy that I found a solution and hopefully this might come in handy for others who might be in a similar situation and would like to use and learn more about VMware VDS.

UEFI PXE boot is possible in ESXi 6.0

10.09.2015 by William Lam // 21 Comments

A couple of days ago I received an interesting question from fellow colleague Paudie O'Riordan, who works over in our Storage and Availability Business Unit at VMware. He was helping a customer who was interested in PXE booting/installing ESXi using UEFI which is short for Unified Extensible Firmware Interface. Historically, we only had support for PXE booting/installing ESXi using the BIOS firmware. You also could boot an ESXi ISO using UEFI, but we did not have support for UEFI when it came to booting/installing ESXi over the network using PXE and other variants such as iPXE/gPXE.

For those of you who may not know, UEFI is meant to eventually replace the legacy BIOS firmware. There are many benefits with using UEFI over BIOS, a recent article that does a good job of explaining the differences can be found here. In doing some research and pinging a few of our ESXi experts internally, I found that UEFI PXE boot support is actually possible with ESXi 6.0. Not only is it possible to PXE boot/install ESXi 6.x using UEFI, but the changes in the EFI boot image are also backwards compatible, which means you could potentially PXE boot/install an older release of ESXi.

Note: Auto Deploy still requires legacy BIOS firmware, UEFI is not currently supported today. This is something we will be addressing in the future, so stay tuned.

Not having worked with ESXi and UEFI before, I thought this would be a great opportunity for me to give this a try in my homelab which would also allow me to document the process in case others were interested. For my PXE server, I am using CentOS 6.7 Minimal (64-Bit) which runs both the DHCP and TFTP services but you can use any distro that you are comfortable with.

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