ubuntu 19/20 move root to external usb drive on a Pi 4

Modified 4/26/20

The following link defines the procedure I used to move root on the sd card to a 32 gib flash drive.   In and earlier post I had made an error in modifying the /boot/firmware/cmdline.txt file.  I did not realize this until today when I had to rebuild a new Pi4  The following link provides the procedure:  move root to usb drive

To VartKat:  my sincere apologies for not getting back to him and to anyone else I may have inconvenienced.

At the end of the above procedure it tells you to modify the /boot/firmare/cmdline.txt file by adding to the end of the existing line the following:  “root=/dev/sda1 rootfstype=ext4 rootwait”.

That line should now look like:  net.ifnames=0 dwc_otg.lpm_enable=0 console=serial0,115200 console=tty1 root=LABEL=writable rootfstype=ext4 elevator=deadline rootwait fixrtc root=/dev/sda1 rootfstype=ext4 rootwait <– a single line entry.  This is where my original procedure screwed up:  I added the string as a separate line rather then appending it to the end of the original line.

If you were successful a df should show:

Filesystem     1K-blocks    Used Available Use% Mounted on
udev             1889668       0   1889668   0% /dev
tmpfs             388440    4596    383844   2% /run
/dev/sda1       58880980 6687384  49172848  12% /
tmpfs            1942188   46584   1895604   3% /dev/shm
tmpfs               5120       4      5116   1% /run/lock
tmpfs            1942188       0   1942188   0% /sys/fs/cgroup
/dev/loop2        223872  223872         0 100% /snap/gnome-3-34-1804/28
/dev/loop0         49664   49664         0 100% /snap/core18/1708
/dev/loop1         63616   63616         0 100% /snap/gtk-common-themes/1506
/dev/loop3         62720   62720         0 100% /snap/lxd/14808
/dev/loop4         48384   48384         0 100% /snap/snap-store/435
/dev/loop5         24192   24192         0 100% /snap/snapd/7267
/dev/mmcblk0p1    258095  104207    153889  41% /boot/firmware
tmpfs             388436      20    388416   1% /run/user/127

Note "/" is /dev/sda1

1 Response to ubuntu 19/20 move root to external usb drive on a Pi 4

  1. VartKat says:


    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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