Deploy ISO Image as File on a FAT32 Formated USB Stick

In KIWI, all generated ISO images are created to be hybrid. This means, the image can be used as a CD/DVD or as a disk. The deployment of such an image onto a disk like an USB stick normally destroys all existing data on this device. Most USB sticks are pre-formatted with a FAT32 Windows File System and to keep the existing data on the stick untouched a different deployment needs to be used.

The following deployment process copies the ISO image as an additional file to the USB stick and makes the USB stick bootable. The ability to boot from the stick is configured through a SYSLINUX feature which allows to loopback mount an ISO file and boot the kernel and initrd directly from the ISO file.

The initrd loaded in this process must also be able to loopback mount the ISO file to access the root filesystem and boot the live system. The dracut initrd system used by KIWI provides this feature upstream called as “iso-scan”. Therefore all KIWI generated live ISO images supports this deployment mode.

For copying the ISO file on the USB stick and the setup of the SYSLINUX bootloader to make use of the “iso-scan” feature an extra tool named live-grub-stick exists. The following procedure shows how to setup the USB stick with live-grub-stick:

  1. Install the live-grub-stick package from software.opensuse.org:

  2. Plug in a USB stick

    Once plugged in, check which Unix device name the FAT32 partition was assigned to. The following command provides an overview about all storage devices and their filesystems:

    $ sudo lsblk --fs
    
  3. Call the live-grub-stick command as follows:

    Assuming “/dev/sdz1” was the FAT32 partition selected from the output of the lsblk command:

    $ sudo live-grub-stick LimeJeOS-Leap-42.3.x86_64-1.42.3.iso /dev/sdz1
    
  4. Boot from your USB Stick

    Activate booting from USB in your BIOS/UEFI. As many firmware has different procedures on how to do it, look into your user manual. EFI booting from iso image is not supported at the moment, for EFI booting use –isohybrid option with live-grub-stick, however note that all the data on the stick will be lost. Many firmware offers a boot menu which can be activated at boot time. Usually this can be reached by pressing the Esc or F12 keys.