2012-06-20 Initial Post
This VMware KB has instructions for installing ESXi 5.0 on USB drive but doesn't mention upgrading an ESXi 4.1 USB drive.
The upgrade is pretty simple and seems to have worked fine, but now my Virtual Machine Startup and Shutdown settings no longer work. I've deselected "Allow virtual machines to start and stop automatically with the system," rebooted, and then re-selected and rebooted, but it still doesn't work.
Here's how to do the USB upgrade:
Make a CD from the ISO, boot your server off the CD and go through everything like it's a new install and select your USB drive. The installer will detect that ESXi is on the USB drive and give you the option to install (default) or upgrade. You'll get another prompt to confirm the upgrade.
I used this ISO:
VMware ESXi 5.0 Update 1 (CD ISO) Installable
2012-03-15 | 5.0.0U1 | 293 MB | Binary (.iso)
My server is Dell PowerEdge T110. See related post http://sysadmin-e.com/vmware-esxi-4-1-usb.