Continuing to upgrade your environment to vSphere 5.5 with Update Manager, after upgrading vCenter Server and other components, the next step will be the upgrade of the ESXi hosts to the version 5.5. As we saw in a previous document, we can also perform the update manually. We will be able to directly migrate the ESX 4.x to ESXi 5.5 or upgrade the ESXi 4.x or 5.x directly.