You can format a USB flash drive to boot the ESXi installation or upgrade, however VMware don't makes it easy for you.
In the old days, you only had to download the official .iso image, and burn it to a flash drive, then ready to go.
Nowadays this is not gonna work, you have to follow a long procedure instead.
- Linux machine with superuser access,
- USB flash drive,
- The ESXi ISO image,
- Syslinux package installed
You have to follow the preparation procedure documented in the official installation guide.
As I had to prepare several ESXi machines regularly, I just created a script to make this process easy again. There is no magic inside, but just following the official guide.
The only thing you have to adjust is the MBR file location provided by your syslinux package, then you are ready to go.
The usage is very simple:
# create-esxi-image <ISO Image> <USB Device>
Even if I tried to make it fault-tolerant, the script will wipe the given block device on your machine, so you should be careful!
Use at Your own risk!