Upgrading to vSphere 4.1 via a SSH CLI Session

I was tasked with upgrading a clients vSphere installation from vSphere 4.0 to 4.1.  Due to various external factors the client couldn't make use of the vSphere Update Manager, so I had to do it old-school style from the command line.  Here's how to do it:


Download the required updates

1.  Navigate to http://downloads.vmware.com/d/info/datacenter_downloads/vmware_vsphere_4/4
2. Download pre-upgrade-from-ESX4.0-to-4.1.0-0.0.260247-release.zip
3. Download  upgrade-from-ESX4.0-to-4.1.0-0.0.260247-release.zip

Install the updates

1. Put your ESX host in maintenance mode with the following command: vimsh -n -e /hostsvc/maintenance_mode_enter
2. Install the pre-upgrade patch:  esxupdate update --bundle=pre-upgrade-from-ESX4.0-to-4.1.0-0.0.260247-release.zip
3. Install the actual upgrade patch: esxupdate update --bundle=upgrade-from-ESX4.0-to-4.1.0-0.0.260247-release.zip
4. Reboot the ESX host via the reboot command
5. Last step is to exit maintenance mode: vimsh -n -e /hostsvc/maintenance_mode_exit

 All of the above can of course be automated using the Update Manager, but for those occasions where it's not possible to use it the above will come in handy.