Need advice on upgrading TP-WDR4300 from OpenWRT Barrier Breaker w/ Extroot

I need to upgrade a 3+ years old install of OpenWRT on my main router here at home. I'd like to move to a current firmware release that I can actively maintain. LEDE 17.01 seems the obvious choice, so I'm preparing to upgrade when it is released. Unfortunately I'm not an OpenWRT expert, and I need some help.

My router is a TP-WDR4300 v1 with 8MB flash, 128MB ram. I'm running OpenWRT Barrier Breaker r39755 / LuCI Trunk (svn-r9957). I've added Mosquitto, OpenVPN and 6in4 tunnel packages.

My main concern is that I'm (probably unnecessarily) running in an Extroot environment, using a 16GB USB key mounted as /dev/sda1. I've been reading the command line install instructions here and feel fairly comfortable with the basic approach, but wanted to understand how this works with the Extroot environment before doing something "stupid" :slight_smile:

Also, are there any specific recommendations for upgrading from such an old version of OpenWRT, or should it not matter?

Thanks!

It should not matter, as best practice would be sysupgrading without retaining your settings (do back them up before so you can use them as a reference to reconfigure after upgrade).

With 8 MB flash, it sounds like you could cram it all into the firmware image - so I'd suggest you look into the image builder to repackage the image you flash; then just mount your USB key as storage, and not as your root FS.

Thanks @Borromini. I had a look at the usage of the various partitions, and agree: unless LEDE is massively larger than OpenWRT then it appears that I should be able to fit everything into the standard flash of the router. The Extroot appears to be unnecessary.
So on that basis (and with your added information about best practice) I think my best approach will be to backup the configurations, revert to "non-Extroot", and then sysupgrade.
I'll take a look at the image builder next.
Thanks!

Just a quick follow-up for any subsequent readers:
I finally got some free time to go ahead with this, and downloaded the latest LEDE firmware for the router, backed up up the router configuration files, powered it down, removed the Extroot device and rebooted.
I was then able to carry out a sysupgrade via the Luci interface. My 2014 UK-spec WDR4300 doesn't have locked down firmware, and the upgrade ran flawlessly. I then reconfigured the basic router function manually, using the backed up configuration files as templates.
As expected, there was plenty of room in the flash, so I didn't bother reapplying Extroot. Getting basic routing & WiFi up and working took me about an hour. So far all is working well.