Before running the installation script, BE sure to check the command "sudo fw_printenv" (from The armbian system running from the SD card). Only if you get the output of variables from u-boot, you can proceed to the installation.
The script performs a "smart" copy (copied the required files and directories). Therefore, it does not matter what size of the external media. It is important that the size of the data on an external drive was smaller than the size of eMMC (/dev/data). The size of the data can be roughly estimated by the "df -h" command. If the user data is smaller than the /dev/data partition on the eMMC, you can perform the installation (run the script /root/install.sh). Yes, you understood correctly. Rename " db.img" the system was not used. Start the Arabian system from external media. Open terminal and execute from the SD card on behalf of the root user, the script "/root/install.sh" .