After you have downloaded the package – proceed to update your host.

The example below is a VM installed with latest build of ESX3i (158874)

Open the VMware vSphere Host Update Utility (this will not work with the VI 2.5 client – it must be the vSphere 4.0 version) and select the host you would like to upgrade

Add the Upgrade file. The file is verified

Accept the EULA and enter Credentials

You will have to have put the host in Maintenance mode beforehand otherwise you will receive an error like this

Compatibility checks are run – in my case this did not work the firs time round because the VM only had 1GB of Ram allocated so I got this. Duncan has written an informative post on the matter and how to manipulate the amount of RAM if you need to.

So after adding additional RAM to the VM the compatibilty check passed

And The Upgrade Process Begins

And after waiting a while the Host is updated with the new version of ESX

A Few points to note:

1. Do not close the Host Update Utility during the upgrade otherwise you will most probably mess up your host
2. You of course need the minimum amount of memory (2GB) for the upgrade to run
3. When the host comes back online it will be in evaluation mode – you will have to provide a license for it.(you have 60 days)
4. Of course your host has to be in Maintenance Mode before you upgrade.

Happy Upgrading!