ubuntu 19 move root to external usb drive on a Pi 4

The following link defines the procedure I used to move root on the sd card to a 32 gib flash drive.   here is the link.   Note:  the link provided has an error at the end of the procedure but I have corrected that error here in what follows.  Or at least I hope I have.  

To VartKat:  my sincere apologies for not getting back to him..

At the end of the above link is some procedure which does not work.  It tells you to edit the /boot/cmdline.txt file and put the following in the file:  root=/dev/sda1 rootfstype=ext4 rootwait  I could not get this to work but as for the rest of the procedure at the above link it does work. It was as if the pi ignored reading the /boot/cmdline.txt file.

What follows is the correction needed at the end of the above procedure.  So follow it then return here.

After following the instructions in the above link I had no /etc/vfstab.

My /etc/fstab looked like the following (I did not edit or make changes):

LABEL=writable / ext4 defaults 0 0
LABEL=system-boot /boot/firmware vfat defaults 0 1

I modified /boot/firmware/nobtcmd.txt to look like the following:


net.ifnames=0 dwc_otg.lpm_enable=0 console=ttyAMA0,115200 console=tty1 root=LABEL=writable rootfstype=ext4 elevator=deadline rootwait fixrtc


net.ifnames=0 dwc_otg.lpm_enable=0 console=ttyAMA0,115200 console=tty1 root=/dev/sda1 rootfstype=ext4 elevator=deadline rootwait

“fixrtc” is fix realtime clock.  I removed it.


1 thought on “ubuntu 19 move root to external usb drive on a Pi 4

  1. VartKat


    You are the only one getting this config to work and as I’m in this situation I have a few questions.

    You talk about /dev/sda1 can you confirm that it is the only partition you got on your SSD, on mine (as I flashed the same image on the SSD and the SDCard) I have a /boot partition, I suppose you don’t have.

    I’m also surprised to see /dev/sdaX works as I read in Ubuntu 19 they moved to root=LABEL=DiskLabel.

    Thanks for yoru help



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