We currently have 20 ESXi 3.5 U4 hosts that we would like to upgrade to vSphere / ESXi 4.0 U1. Is an upgrade of ESXi just as good/clean as a fresh install? What are peoples opinions?
I am sure there are proponents for both sides.
I am going the clean install route, for the Vcenter and the ESX hosts in the next week or so, but I also have another issue where I need to first somehow virtualize my current vcenter, then use that server to build the new vsphere vcenter.
and I'm not completely sure P2V-ing the Vcenter will work. especially if I'm P2Ving itself to a virtual...
Is this a harddrive install or USB? I don't know whether the USB upgrade has changed in U_1 but 3.5 to 4 was unsupported. Some installs had partition issues.
From my experience the upgrade has been very easy and works well. The upgrade replaces the boot partition (bootbank) and then copies over the configuration so you do have a "fresh" install.
I say clean as well. Even if you do use VUM, a clean install would be quicker.
..if using vCenter to manage these ESXi Hosts, it should be fairly painless as you can leverage DRS. Just remember to update/upgrade vCenter first.