Are ASU and OWUT safe with extroot?

Installing and Using OpenWrt
1

Now that 25.12.3 has been released, this has become topical for me. The ASU page (Last modified: 2026/03/28 06:40by xirixiz1) has only this note regarding extroot:

Extroot configuration

Note that if your device is configured for Extroot, then you will need to reboot twice after any sysupgrade. The external root filesystem does not remount after the first boot. There is no need to modify or recreate extroot settings, just reboot again and the configuration will work as before and continue to do so.

I had to do a fresh install after 25.12.1 upgrade (ASUS TUF-AX4200, MT7986AV). Luckily, as I’m a bit paranoid (due to 35 years in IT), I had all the relevant config files backed up, so it wasn't a disaster or a 24-hour overnight session :winking_face_with_tongue: . I had a spare 500GB NVMe lying around and an enclosure, so I decided to set up extroot to ensure enough disk space for Docker and apps (and whatever...).

Thus, I would be happy for a confirmation that both ASU and OWUT will actually work with extroot and keep all apps and settings. And after two reboots all would be exactly like it was. Asking this because the on Extroot page (Last modified: 2026/01/09 18:37 by phinn) it says:

Automated setup

You can use the openwrt-auto-extroot ImageBuilder frontend to build a custom firmware image that will automatically format and set up extroot on any plugged-in, but not yet setup storage device.

Automated upgrade

Set up Hotplug extras and Opkg extras. Packages required by Extroot should be saved in the init Opkg profile and restored automatically after upgrade following by the script to reconfigure Extroot.

cat << "EOF" > /etc/uci-defaults/90-extroot-restore
if uci -q get fstab.extroot > /dev/null \
&& [ ! -e /etc/extroot-restore ] \
&& [ -e /etc/opkg-restore-init ] \
&& lock -n /var/lock/extroot-restore
then
UUID="$(uci -q get fstab.extroot.uuid)"
DIR="$(uci -q get fstab.extroot.target)"
DEV="$(block info | sed -n -e "/${UUID}/s/:.*$//p")"
if touch /etc/extroot-restore \
&& grep -q -e "\s${DIR}\s" /etc/mtab \
&& mount "${DEV}" /mnt
then
BAK="$(mktemp -d -p /mnt -t bak.XXXXXX)"
mv -f /mnt/etc /mnt/upper "${BAK}"
cp -f -a "${DIR}"/. /mnt
umount "${DEV}"
fi
lock -u /var/lock/extroot-restore
reboot
fi
exit 1
EOF
cat << "EOF" >> /etc/sysupgrade.conf
/etc/uci-defaults
EOF

Just checking as well that docker (in /opt/docker) will survive the upgrade. I’ve only just got adguardhome and wg-easy running. Reverse proxy (caddy) is the next step.

Thank you in advance!

Temexter

2

You'll need to try it out and see if it works. sysupgrade itself (owut really doesn't figure in here, it's just a delivery wagon for the image) does not consider the existing partition table as useful in most cases, so simply overwrites it, so it may work or it may not, it all depends on what your scripts are doing...

3

Thanks for the comment. My “scripts are doing...”… nothing. As no scripts are involved (those scripts are for extroot upgrade).

I only asked for a confirmation that ASU (or OWUT) support extroot. Because on the ASU documentation page is says - as I already quoted:

Note that if your device is configured for Extroot, then you will need to reboot twice after any sysupgrade. The external root filesystem does not remount after the first boot. There is no need to modify or recreate extroot settings, just reboot again and the configuration will work as before and continue to do so.

I understand that quite implicitly suggests that ASU supports extroot. Still would definetely be happy of someone who has succeeded in that to confirm it. I’m definitely not “just gonna try”!