I'm currently upgrading our VMWare environment from vSphere 4.0 to 4.1. First, I moved the vCenter installation from a 32bit physical box into a 64bit VM on a vSphere 4.0 ESX host.
I have since upgraded a test ESX host to 4.1 using the Update Manager, which is also running on the same VM as the vCenter Server. So far so good.
Now I need upgrade the ESX 4.0 host to 4.1 on the same box that hosts the vCenter & Update Manager installations.
Are there any known issues with this? Probably due to lack of understanding of the internals of the upgrade process, I'm slightly nervous about this. Is there any real need for the vCenter Server and/or Update Manager to up/available during the host upgrade?