So first post about the free Hypervisor under its new name.
I wrote an article regarding the process of upgrading from ESXi 3.5 to ESXi 4.0.
Well I am happy to announce that this has changed - again! Have you tried to find the VMware vSphere Host Update Utility? It was never downloadable - it was part of the vSphere Client which was bundled with your ESXi Installation.(by the way that has also been removed from the installation and is not a separate download as well.
What once was
The reason that the download is actually almost 160MB larger with less inside is a mystery to me (I guess the multiple languages now built in - make it a lot larger). But there is no Host Update utility any more.
If you still want to update your hosts you will have to revert to a bit of command-line work.
The solution to this in the Upgrade Guide.
What you will need is:
A Scratch Partition on your ESXi host
You must configure a scratch partition and reboot the host before proceeding with the upgrade.
You can configure a scratch partition for a host under the Software Advanced Settings in the Configuration tab of the vSphere Client.
What is the Scratch Partition?
During the autoconfiguration phase in the Host installation process, a 4GB VFAT scratch partition is created if the partition is not present on another disk. When ESXi boots, the system tries to find a suitable partition on a local disk to create a scratch partition. The scratch partition is not required. It is used to store vm-support output, which you need when you create a support bundle. If the scratch partition is not present, vm-support output is stored in a ramdisk. This might be problematic in low-memory situations, but is not critical.
For ESXi Installable, the partition is created during installation and is thus selected. VMware recommends that you leave it unchanged.
vSphere CLI - Download Here
Download the tool - For Windows or Linux and install on your workstation.
Power off your VM's and put the host into maintenance mode
Change your current directory to C:\Program Files\VMware\VMware vSphere CLI\bin
From the vSphere CLI prompt
vihostupdate.pl --server host name or IP address -i -b location of the ESXi upgrade ZIP bundle -B ESXi410-GA
So in my case
vihostupdate.pl --server msaidelk-esx -i -b c:\temp\upgrade-from-ESXi4.0-to-4.1.0-0.0.260247-release.zip -B ESXi410-GA
You can of course do the same thing with ESX Updates as well
vihostupdate.pl --server host name or IP address -i -b location of the ESXi upgrade ZIP bundle -B ESXi410-GA-esxupdate
A reboot of the host is necessary thereafter.
Updated the syntax to include the .pl extension to the command and added Step 5.