In theory, you can just migrate to scale with the updater.
However, when I did a few month ago, something went wrong and if I remember correctly GRUB was broken. So I had to reinstall it with the ISO. Thankfully I downloaded a backup before. Just reimported the backup and all was running fine again. I recommend you do the same.
It’s not currently being called out directly in the Preparing to Migrate article, but if you continue to the Community Migrations guide, it says:
TrueNAS users wanting to migrate from the latest FreeBSD-based 13.0-U6 or 13.3 CORE release to the Linux-based TrueNAS version 24.10 or later can migrate to 24.04 and earlier using the UI update process, but must clean install if migrating to later releases. Attempting to migrate directly to 24.10 or later using the UI is not supported.
TrueNAS community users can download a copy of the iso for the latest maintenance release of the target major version, then follow the migration instructions in Performing a Clean Install or use the UI update screen or download a manual update file then follow the instructions in Updating to 24.04 to move from the FreeBSD-based to the Linux-based version of TrueNAS.
When i sidegrade from Core to Scale, i make a clean EEL install (was the latest release at time) on a different disk as already suggested, then i upload the Core config file… All gone smoothly but in case of needs i could just swap with the old disk
Not considering migrations apps, as far i remember i have had to change some commands in Cron, create a new admin user (be careful on the new admin home folder a miss config on my side there give me some headache), and i have to re apply some ACL here and there that prevent new apps to work properly
Thanks for the replies everyone, and apologies for the delayed response, I was called away with work.
A quick synopsis of all the replies would seem the following is UI and worth considering.
I will read and absorb the Community upgrade procedure as suggested by DjP-iX
It seems the general concensus is to go from Core to Electric Eel first using the built-in upgrade option. I did read somewhere else to…
Make sure to mount volumes and check integrity
Then upgrade to Fangtooth
Again make sure volumes are mounted and check integrity
Ensure good backups, thanks Sara
Etorix suggested “clean install on a new boot device and keep the CORE boot device to revert if anything goes wrong.”
This is something I can do. I use ~80GB SSD’s as a USB boot device (motherboard mounted and stored in the case) and have a few lying around.
Thanks oxyde, only app I currently use realistically is Plex and I know I will lose that and have to reinstall. In fact, that was what instigated this whole thing. Looking into JellyFin as an option too.
Oh well time to start reading and keep my fingers and toes crossed.
a miss config on my side there give me some headache), and i have to re apply some ACL here and there that prevent new apps to work properly