First, I know that Unraid is not FOSS and I'm a month late, just to get that out of the way. But for those that are running Unraid and haven't updated to >7.3.0, there's good reason to (other than for security patches): internal boot and TPM licensing.

This update allows you to boot from an internal drive, no more chewing up flash drives. As a long time Unraid user (for over a decade), this was a long time coming. My server ate several flash drives. Setting it up was a breeze, once I updated to 7.3.x, the wizard to configure it came up and I was able to move it to one of my internal SSDs. All I had to do after that was go into the BIOS and set the boot priority correctly.

Internal boot works without a TPM, however you'd still need the flash drive with your license on it plugged in at boot. If you have a TPM on your server, though, you can migrate your license from your flash to your TPM, with another simple wizard. After migration, you no longer need a boot flash drive.

I had to get a Supermicro AOM-TPM-9665V TPM chip for my motherboard, but I've got it all set now. It's a relief to no longer have to rely on flash drives now - my server's rear exhaust fans were blowing directly on them, causing them to overheat and eventually crash my server.

Unraid posted about this in their blog here: https://unraid.net/blog/unraid-7-3-0