Update 1 for VMware ESXi has been out for a couple months now with no major issues, so we decided it was finally time to make the jump from ESXi 6.0 Update 3 to ESXi 6.5 Update 1. I accomplished this using Update Manager in vCenter as described in the following steps.
1.) Navigate to the first host you wish to upgrade and select the Update Manager tab. Here confirm that you are compliant with the Critical Host Patches (Predefined) baseline. If you’re not, I would suggest getting all of your patches installed prior to upgrade. Probably not necessary, but it gives me that warm and fuzzy feeling.
2.) Once you have that under control we will need to upload the actual ESXi ISO for the update. We can’t do this where we are currently, so select the Go to Admin View on the top right.
3.) Select the Manage tab, then select ESXi Images, and finally click Import ESXi Image…
4.) Once you have your ESXi Image uploaded, select the Host Baselines tab and select +New Baseline…
5.) Give the baseline a name and description, select the Host Upgrade radio button, and select Next.
6.) Select the ESXi image that you just uploaded and select Next.
7.) You should see a little summary page. Confirm your settings and select Finish.
8.) Now that we have our baseline, we need to attach that baseline to the host we wish to upgrade. Navigate out of the Admin View back to the Update Manager tab of the host you are upgrading and select the Attach Baseline… in the top right corner.
9.) Select the upgrade baseline you just created and select OK.
10.) Your host will now show that it is Non-Compliant because it does not meet the host upgrade baseline we just attached. Select the Remediate… option in the top right to begin the upgrade process.
11.) Select the baseline you created and select Next.
12.) Select the host you wish to “remediate” (aka the host you want to upgrade) and select Next.
13.) Accept the EULA and select Next.
14.) On the Advanced Options menu you can choose to schedule the upgrade if you like. When ready select Next.
15.) On the Host remediation options page you have options for PXE booting, maintenance mode on failure settings, VM Power State, and so on. Select what makes sense for you and select Next.
16.) On the Cluster remediation options you have a number of options available to disable. I disable FT and HA admission control, but choose what suites your environment and select Next.
17.) Review the summary page and select Finish to get things started.
At this point, go grab some coffee and relax. If you iLO or something similar you can watch your host reboot a couple times. For my hardware this entire process took roughly 10 to 15 minutes. Once you are back up, take your machine out of maintenance mode and you’re good to go!