I have an 8GB USB flash drive as the boot device on a host which is running ESXi 6.0. I booted the 6.5 installer CD (Dell Customized ISO) and after I selected the USB drive for the upgrade location, it couldn't continue, citing a lack of available space.
The host began life running ESXi 5.0, and has been upgraded to 5.1, 5.5, 6.0 over the last 4 years. I have another identical host at a different site, which is the same age and has had the same upgrade cycle. I was able to upgrade to 6.5 on that one without a problem. I've confirmed the host is not using the flash drive as a scratch location.
I need some ideas. I'm guessing there's some old leftover stuff on the flash drive from prior builds. Is there a way to investigate & free up space? Worst case scenario is I replace the flash drive with a larger one and rebuild the host from scratch, but that is a very undesirable option!