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How to use vCenter Server Appliance to upgrade ESXi hosts

You upgraded vCenter to version 6.5; what comes next? Upgrade your ESXi hosts to gain access to new features and functionality by following these steps.

One of the major benefits of the latest version of the vCenter appliance is that it comes with the natively integrated...

vSphere Update Manager, which makes the process of upgrading hosts easier. This means no more complex vSphere Update Manager setups of wrangling with databases.

Once you've upgraded VMware vCenter, the next step is to upgrade ESXi hosts. In this article, we'll talk about how to upgrade ESXi hosts to ESXi 6.5.

If your current environment was originally installed with custom ESXi images, you're better off waiting to upgrade hosts until the vendor provides an updated ESXi install image, as you may find that some of the drivers for the hardware aren't supported in the base image from VMware. Other than that, download the latest installation of ESXi 6.5 for use in the update.

In order to upgrade ESXi hosts, you must first re-enable Distributed Resource Scheduler and make sure that vMotion is working. If you neglect to do this, you may experience issues trying to upgrade hosts due to their inability to migrate VMs to alternate hosts.

If your current environment was originally installed with custom ESXi images, you're better off waiting to upgrade hosts until the vendor provides an updated ESXi install image.

Once you're satisfied that vMotion is working properly, start the upgrade process by logging into the vCenter web interface. You can only gain access to new functionalities and features, such vCenter High Availability and VM Encryption, through ESXi 6.5 and the vCenter Server Appliance (vCSA); neither Windows-based vCenter, nor the fat client offers these features.

Although ESXi 6.5 includes the HTML5 client, this new client does not yet have all the functionality of the old Flash-based client. For that reason, I've used the Flash client for this upgrade demonstration.

From the vCenter homepage, select Update Manager from the third row of icons, and then click the Admin View button. Select ESXi Images, and then Import ESXi Image from the toolbar shown in Figure A. Navigate to your saved copy of ESXi 6.5 and press Upload to import it. This will take several minutes to upload.

Import the ESXi Image.
Figure A. Import the ESXi Image.

At this point, we need to create a new baseline configuration for the upgrading hosts to use based on the ESXi 6.5 image we uploaded.

Select Host Baselines and click New Baseline. Give it an appropriate name -- for example, ESXi 6.5 upgrade. I'd recommend giving it a good description, as this new baseline will be used in parts of the GUI for pop-out description boxes.

Since this is an upgrade rather than a host extension or patch, the administrator needs to select Host Upgrade for the baseline type, and then click Next.

After clicking Next, the administrator must choose which image to use. The ESXi 6.5 install image should be visible, as shown in Figure B. Select this image and click Next.

ESXi 6.5 install image
Figure B. Select the ESXi 6.5 install image.

Finally, you'll see the confirmation screen, shown in Figure C. Review the settings, and then click Finish to accept the setup.

Review ESXI 6.5 upgrade settings
Figure C. Review the settings for your ESXi 6.5 upgrade.

Back on the Host Baselines screen, you should see the custom upgrade baseline you just created. At this point, you need to attach the newly created baseline to the ESXi hosts. Click Go to compliance view. This allows you to attach the baseline.

Select a host from the menu on the left and click Attach Baseline. This brings up a selection of Baselines, including the upgrade baseline you've created. Select the ESXi 6.5 upgrade under Upgrade Baselines.

This will pull up a wizard to perform the upgrade. The ESXi upgrade should be preselected in the first screen of the wizard, so just click Next. The next screen that appears shows the host you're trying to remediate -- just click Next.
Following the End User Licensing Agreement page, a screen appears enabling you to configure a scheduled point for the upgrade to run. You won't be using that for this upgrade, so just click Next.

You can set advanced host options on the host remediation, but be careful -- some of these options are dangerous if you don't fully understand them. For example, if you change the VM power state option, it may resort to powering off VMs to perform the upgrade. Leave all the options on this page as is, unless you have a good reason to modify them.

The only thing you do want to do on this page is tick the box labeled Save as the default host remediation options. As its name implies, this saves the configuration we built as the default remediation option, saving you time down the road. This feature is new to ESXi 6.5

On the penultimate page, set the configuration options as needed. Once you have done this, click Next. Review the final details on the last page, then click Finish. The wizard will now remediate the host; be aware that this may take a while to complete.

It is wise to run a precheck remediation, shown in Figure D, as this can highlight any issues that may prevent a successful upgrade.

Run a precheck remediation.
Figure D. Run a precheck remediation before upgrading.


At points during the remediation, it may seem as if the upgrade process is stuck, especially when it reaches 22%. Fear not -- this is simply when the server is caching all the files, and it should eventually complete.

Repeat this process for each node. Hopefully, the administrator ticked the box marked Save as the default remediation options in order to use the settings selected when upgrading the first host for all the subsequent hosts. Once the remediation is complete, so, too, is the upgrade of vCenter and ESXi hosts.

As a side note, the administrator may find that the storage is using an older version of Virtual Machine File System (VMFS). Although you can upgrade these, from past experience, there's more to gain by doing a storage vMotion from one data store to another, and then deleting and recreating the data store with the latest version of VMFS.

Next Steps

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