I would like to migrate my Raspberry Pi OS from SD card to external disk. In various posts I have read that Raspberry Pi 3 and 4 should support it out of the box.

However, when I just dd disk image from SD card to external disk, the Raspberry does not boot from the disk - looks like it does not find boot sector. I assume that the reason is that booting from disk needs different file structure than from SD card.

Would anyone know how to prepare booting (or fix boot on disk which has been created by dd from SD card) on disk, so I can just dd whole partitions? The configuration of OS on SD card is so complex that I believe I can not copy disk file by file (HASSIO).

1 Answer 1


I used the SD Card Imager in the menus. Choosing the sd card as the source the external USB as the destination. clicking on the randomize UUID option. This used the entire drive it was installed on. To be able to boot you need to have it setup properly with the respi-config to boot rom usb after checking the boot loader to see if it support is possible.

root@buster-raspi:~# vcgencmd bootloader_version
Dec 11 2020 11:15:17
version c3f26b6070054bca030366de2550d79ddae1207a (release)
timestamp 1607685317

You need to see at least Sept 02 the version I had at the time that worked for me, perhaps earlier I am not sure on those ones, only what I have experience with. To see the support is there.

root@buster-raspi:~# vcgencmd bootloader_config | grep BOOT_O

This shows what the setup did with the raspi-config to enable boot from USB that setting there above. A couple of links below, the Chambers link is for the more advanced user with a listing of the good known adapters that will work for USB boot, with work around to do a chainload if not successful. The Toms Hardware has the procedure for doing the raspi-config.

  1. https://www.tomshardware.com/how-to/boot-raspberry-pi-4-usb

  2. https://jamesachambers.com/raspberry-pi-4-usb-boot-config-guide-for-ssd-flash-drives/

  • Thank you. In the meanwhile, I found other posts saying that cloning HASSIO to SSD does not work, the SSD disk never boots. Noone found a way how to migrate HASSIO from SD card to SSD yet.
    – Jan
    Commented Feb 16, 2021 at 14:36
  • Then do not copy the /boot to the SSD and use the chainload method where the /root file system is on the SSD the boot happens from the sdcard. It delays the boot by a few seconds as it reads from the slower card. This gives most all the speed advantage of an SSD to the only really important part needed when it is running the / file system. /boot is only needed when the bootloader files get updated. And when booting of course.
    – user130167
    Commented Feb 16, 2021 at 14:58

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