/VMware: How to upgrade ESXi 5.x to ESXi 6.x

VMware: How to upgrade ESXi 5.x to ESXi 6.x

After we have upgraded our vCenter from 5.0 to 6.x, we now need to upgrade our ESXi hosts. We can upgrade using an ESXi ISO image directly boot the host and manually go through the process and upgrade the ESXi, or we can use the VMware Update Manager to do this automatically. We will explain both procedures in this article.

Note: Before we start, again I need to inform that for security reasons, I need to erase some of the information in some images. Since I have taken this images in the production environment.

Information: Be aware that some ESXi versions, need a vCenter update before ESXi. So before you begin, check in VMware KB if your version needs a vCenter upgrade before any upgrade in ESXi. ESXi will not be able to reconnect to your vCenter until you upgrade your vCenter to the right version.

1- Upgrade to ESXi using VMware Update Manager(VUM):

First, we need to upload our ESXi 6.0 ISO file to our Update Manager so that VUM can use this image to upgrade our ESXi. Connect to your vCenter using the vSphere Client Tool and go to VUM (Home – Solution and Applications – Update Manager)

Note: To use VMware Update Manager  to upgrade or apply patches in ESXi hosts needs we need o use the vSphere Client tool and not Web Client(Web Client doesn’t have Remediate button) Choose “ESXi Images” Tab and click in “Import ESXi Image.”

Just choose your ISO image and upload to VUM In our case, since these are HP hosts, I will add an HP ESXi image.

Now the upload process will start. Wait until is finished with success.

After the import is finish, you need to create a Baseline(if you don’t any in the ESXi Images) that you need to attach to the hosts that will use this upgrade process.


After we upload the image and create the Baseline upgrade, we need now to attach now this new Baseline to our servers, or cluster.

We go back to Host and Clusters and choose tab Update Manager. Select your Cluster, or hosts that you want to attach to this Baseline(in this case the hosts that we will upgrade), then click Attach(upper right corner). In this case, we choose to select the Cluster(and consequently all the hosts inside will be attached)

Then select the Baseline you want to attach. For this case is the one that we created while importing the ISO image, with the name ESXi 6.0. Click Attach button

After the Cluster/Hosts are attached to the Baseline, we will start the upgrade.

Select the same Cluster again (or the host if you attached by host) click the Remediate button that is in the lower right corner.

Next select upgrade Baselines and then select the proper Baseline(in this case we only have the one we have created ESXi 6.0, and all host will be displayed) and then click Next.

Next, check all the information and change what you need for your environment(like move VMs before the upgrade, etc. In this case all VMs were power down, and hosts were already in Maintenance Mode)

In our case, we had this warning. Since we have in this cluster some HP G7, G8 and G9, the upgrade is informing that we should enable Enhanced vMotion Compatibility(EVC) in this cluster.

If you are not so familiar with VMware EVC, you should take a look HERE

Then  click Finish and start the upgrade process.

If you look at the tasks(at the bottom of your vSphere Client Tool), you should see the upgrade task running.

After this, VUM will start the upgrade in the hosts one by one.

In this case, in 8 hosts, 2 did not finish properly. So I decided to upgrade them manually.

2 – Upgrade to ESXi 6.0 using Boot ISO image:

In this case we have an HP G7 to upgrade, so we will use iLO to do this.

Choose and Add the ISO image to the Virtual Drives of your iLO console

Choose the ISO image.

Reboot, or power on the server and then click F11 to start the Boot Menu

Choose 1 to boot from the CD-ROM

Then start to install/upgrade ESXi.

The installation will start to scan any previous installations and disks.

In this case this HP G7 one SD Card with 4Gb(is where ESXi 5.5 is installed) and two local RAID volumes with 300Gb and 1Tb. Since we have some VMs in the local Volumes, we need to leave this untouchable so that we don’t lose any VMs or Data.

We will select the SD Card.

But before we click Enter, we will press F1 to check the details on the SD Card. This will give us the information on the ESXi that is installed in this volume. Or if we have doubts where the ESXi is installed, we can just click F1 in each Volume to give the details.

After confirming that ESXi 5.5 is in this Volume, we select the Volume and click Enter and continue with the upgrade.

After the installation recognise that is a previous ESXi installation on that volume we have the option to do a fresh install(will format and do a clean install), or select the Upgrade option. In our case we are upgrading, so lets just select Upgrade and continue.

Confirm pressing F11 and continue.

After the Upgrade process will start and Finish

After is finished, remove the ISO image from the iLO Virtual Driver, if not host will boot again with the ISO and the installation process.

And now ESXi is upgraded to ESXi 6.0.

Note: Using VUM or manually ISO image to upgrade your hosts sometimes after an upgrade the host cannot connect to the vCenter and the host stays gray-out and says disconnect in the vCenter hosts lists, in this case just right click(wait around 5m after the host is power up) in the host and select the option Connect(this will force the host to reconnect to the vCenter).

Hope this article can you help to upgrade from ESXi 5.5(or 5.0) to ESXi 6.0 with both options.

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By | 2018-12-03T15:02:15+01:00 September 3rd, 2015|VMware Posts|0 Comments

About the Author:

I have over 20 years of experience in the IT industry. I have been working with Virtualization for more than 15 years (mainly VMware). I recently obtained certifications, including VCP DCV 2022, VCAP DCV Design 2023, and VCP Cloud 2023. Additionally, I have VCP6.5-DCV, VMware vSAN Specialist, vExpert vSAN, vExpert NSX, vExpert Cloud Provider for the last two years, and vExpert for the last 7 years and a old MCP. My specialties are Virtualization, Storage, and Virtual Backup. I am a Solutions Architect in the area VMware, Cloud and Backup / Storage. I am employed by ITQ, a VMware partner as a Senior Consultant. I am also a blogger and owner of the blog ProVirtualzone.com

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