Most vSphere admins are more than comfortable with using Update Manager to download patches and update their environment, but few that I talk to actually know a huge amount about the Update Mangaer Download Service (UMDS). UMDS is tool you can install to download patches (and third party VIBs - I’ll get to that) for Update Manager and it’s useful for environments that don’t have access to the internet, or air-gapped, and also for environments with multiple vCenter Servers where you don’t necessarily want to download the same patch on every server.
I’m currently in the process of migrating a 2-host High Availability cluster of ESX 3.5u4 servers to vSphere 4. This is going to come in 3 distinct stages: Stage 1 is to upgrade VirtualCenter Server 2.5 to vCenter 4, which I am going to cover today. Stage 2 is to upgrade each host, and will be covered as I do it. Stage 3 is the upgrade of the Virtual Machines to the latest VMware Tools and then the new VM hardware.