We've currently around 180 remote sites using mainly ESXi 4.1 with around a dozen on 5.1 booting from USB keys. We need to upgrade (due to backup solution compatibility) to a mix of 5,5 and 6.0 (the 4.1 servers aren't on the HCL for 6). Rather than using the host update utility (these are taking money!) we're proposing creating new USB keys and swapping them over as we'll have people in each site over a period of time due to other ongoing projects.
What should I be aware of, do I need to move the VMs anywhere or when we allocate the datastore to the new USB key should it find the VMs (only 2 per site)?
personly i would upgrade on the usb disk instead of creating a new one.
but you should be fine to add the datastore and find the vm's and add them back to the inventory
2 things come to mind at the moment
datastore VMFS version (upgrade to 5.x) planning to upgrade?
and more important the networking have to be correct.