I've been using the same 1GB USB flash drive with unRAID for probably about 15 years now.  I'm finding than anytime I want to upgrade the OS I have to make a backup of the 'previous' folder on the flash drive and then shut down the server.  I pull the flash drive and insert it into my Windows 10 PC and then delete the contents of the 'previous' folder except for the license.txt file (not sure if that matters but I do it just to be safe).  When I reboot the server with the flash drive I now have enough free storage to perform the OS update.  The 'previous' folder is then updated with the backup of the current OS. 

 

Is there a process for upgrading to a larger flash drive without having to purchase a new license?  The size of the drive was more than sufficient when I started using unRAID, but the OS has increased in size over the years so it just makes upgrading the OS a little less convenient as I have just described.  Due to the age of the flash drive I'd rather not keep having to pull it from the server so frequently to perform an OS update.  I'm currently running unRAID OS Pro with the latest 6.12.1.  My server has 28 data drives with a total capacity of 208TB with two 8TB parity drives and a 1TB SSD cache drive.

The process for changing the flash drive is covered here in the online documentation accessible via the ‘Manual’ link at the bottom of the GUI or the DOCS link at the top of each forum page.

I performed the flash drive upgrade but apparently the process has been changed slightly and it has not been reflected in the docs.  Apparently there is no longer a need to enter your email address when clicking on the REPLACE KEY button.  The new key appears to have been downloaded without my email address and gets installed once you acknowledge that the older flash drive has been blacklisted.