Yesterday we did an upgrade from an ESX 3.5 host to ESX 4.0 using the VMware Upgrade Manager. I must say it’s cool to see how you can upgrade your ESX hosts and after that you can schedule the updates for your virtual machines with a virtual hardware upgrade version 7 and new VMware Tools.

There are some prerequisites for upgrading ESX 3.5 hosts to ESX 4.0 by using the VMware Upgrade Manager. Make sure you upgrade your vCenter server to vCenter Server 4.0 and make sure you have updated vCenter Update Manager 1.0 to version 4.0 before attempting to upgrade your ESX hosts.

Steps you should take are:

  • create an ESX 4.0 upgrade baseline
  • select the host to upgrade and attach the baseline to your ESX host or the datacenter.
  • scan your host for updates and remediate your entity.

When following the process in vCenter Server you will see the following tasks in the lower pane:

  • Remediate entity
  • Enter Maintenance mode
  • Exit Maintenance mode

Through an iLO connection with the host in the US we could follow the upgrade process on the console.

On the status bar in vCenter Server in the tasks pane you will see a percentage and underwater you will see the following processes are running:

  • 33% Putting ESX host in Maintenance mode
  • 38% Copying installation files to the ESX server from an ISO or ZIP file.
  • 56% Unpacking and installing files

After unpacking and installing the files the host will reboot and after a 10 min reboot cycle you will see 100% host upgrade successful.