I usually use RAID1 w/ local SAS for my ESXi boot volumes on practically every server I have ever worked on. However, I deployed an R430 for someone, using all eBay parts with the intention to build as cheap as possible. This resulting in me using a USB stick for the ESXi boot drive.
In this situation, it is a good idea to have a backup USB in case for some reason the primary install fails to boot. I tried using Clonezilla, DD, and USB Image Tool to accomplish this, and all failed. Huge shoutout to virtual hobbit, who provided some instructions for using GParted to clone it. This should work on 5.5 and 6.0 also.
Once you are in Gparted, plug in your ESXi install and the USB you want to clone to. Refresh the drive list. The command to clone the partition table is the following syntax:
sgdisk –replicate=/dev/target /dev/source (might look something like this sgdisk –replicate=/dev/sda /dev/sdb)
Once that is complete, you can copy and paste the partitions to the blank USB, then click apply. One of the partitions seems to show “unknown” and can’t be copied, but it did not affect the usability.
See virtual hobbit’s post for much more details and screenshots!