Advice on release upgrade from Xubuntu 18.04.6 to 20.04.6 through 24.04.x
I have a computer running what I think at the time was called Ubuntu Server (no GUI) that I installed Xfce on, making it essentially Xubuntu. I did this because it allowed me to use mdadm to set up RAID (4 drives; RAID 5) during the OS install.
My OS lives on an NVME drive, and I have my raid mounted at /Files.
I have lots of data in my RAID, and much (but not all!) is backed up to the cloud. There would be both emotional issues and lots of time required to fix things if I lose the RAID or the data on it.
(I am realizing as I write this that I put off upgrading so long, I can probably copy all the data to one 20TB drive (oof! That’s expensive) since they’ve gotten about as big as my 21.83TB volume.)
How safe is it to take the OS up on this offer?
New release '20.04.6 LTS' available.
Run 'do-release-upgrade' to upgrade to it.
How hard is it to reestablish the RAID if it forgets it exists?
Is there anything else I can do to make this more likely to “just work”? (Like: don’t do it over ssh)
That's enough upgrades it could cause some issues, but I wouldn't expect it to be a problem with the RAID array itself, mostly applications and configs that don't work anymore because you're jumping 6 years into the future in terms of software versions. Some things like PostgreSQL you have to dump the data out, install the new version and load it back in, so that's one example of something that could break and would be expected to break.
I believe if you just boot the 24.04 installer it'll see the drives right away, they're pretty persistent. But failing that, you can assemble it manually with mdadm --assemble, or you can backup your /etc/mdadm.conf. That should give you some confidence that if something wrong happens with the Ubuntu install it will be easy to reinstall fresh and not lose your array. Just get it mounted readonly in the live ISO so you know how to get your data, and you'll feel a lot safer doing the upgrade.
Thank you! That command and file to backup are the kind of info I was after.
And I appreciate the reminder that applications and configs might not work. I plan to test everything after each upgrade (I don’t plan on jumping straight to 24.04).
I do already know the version of TigerVNC, for example, I’m using is not the same as the latest, and I’ve seen it works a bit different on my machines with newer OS versions. Also I seem to remember Firefox needs to be installed as deb not snap or it won’t work with TigerVNC. So I’ll make sure to backup my profile folder for Firefox.
This computer is mostly a file server, I’ll have to do an inventory of what software I’ve used on it over the years.
Boot a live image of the new version and see if it Just Works. It probably will.
If you can, back up the OS (and make sure a restore works) and try the upgrade. If you can just clone the OS to a new drive and upgrade that one so you can swap back, even better. I don't think there's anything like a RAID version upgrade that's going to prevent you from reverting.