Help with some doubts about reinstall fedora with btrfs

I’m talking from complete ignorance and I’m not blaming anyone, I can´t find the post but, there was a question asking if using btrfs for a fresh install of Fedora 33 it could be possible to reinstall the system only formatting the ‘/’ subvolume, most of the answers were like ‘yes you can’.

So I’ve installed F33 with defaults values and think that home and root will be separately, but now i want to update to F35 i can only assign the /boot and /home as mounting points but no the root, so it’s possible that the default config for installation puts the /home inside the root?

Screenshot of the manual partitioning:

Trying to understand listing the btrfs subvolumes i get this:

$ findmnt -nt btrfs
/       /dev/nvme0n1p2[/root] btrfs  rw,relatime,seclabel,ssd,space_cache,subvolid=257,subvol=/root
└─/home /dev/nvme0n1p2[/home] btrfs  rw,relatime,seclabel,ssd,space_cache,subvolid=256,subvol=/home

I don’t want to upgrade using dnf (DNF System Upgrade :: Fedora Docs), this method never works for me because the new system was always slower than the previous or get more anoying and random errors (i only have the rpm fusion as external repo) so i ended doing a clean install when i want to upgrade to a newer version.

If the only way to solve this is a fresh install, there is a way to use ext4 again on installation?

any help would be appreciated.

It will help you

thanks for the answer but this don’t help me

That means you have one btrfs partition with subvolumes mounted on /home and /.

I am not sure exactly what you are trying to but if you are trying to preserve /home and overwrite the rest of the system you can do that via manual partitioning.

Hi Gerson. The installer currently doesn’t make it super obvious how to do what you want, which is to preserve the existing /home contents, and create a new / to install to.

The installer enforces the creation of a new file system for / when on ext4 and XFS but it’s different on Btrfs. There’s a partial exception: you don’t need to reformat the Btrfs volume, but you do need a new subvolume for /.

Fortunately the installer will create a new subvolume for you if you add a new / mount point rather than reusing the existing one. You can optionally delete the current / in the installer or do it post-install, it really depends on how much space you have and how attached you are to any of the contents in the “old” /

There is a Fedora QA test case that describes how this should work. It’s not pretty because it’s not a user facing document (yet), it’s targeted at testers. But it should help you navigate the installer’s idiosyncrasy for your use case.

Your screenshot above is pretty much at the “How to test” step 6 portion of this test case. Make sure you check step 5, and ensure that the partitioning scheme has been set to the default: Btrfs. The manual partitioning UI enforces rules based on this partition scheme selection.

Let us know how that works for you, in particular if you get stuck at any step along the way.

Many thanks that was the info that I’ve need, you save me a lot of time making a backup and a clean install, is there a possibility that the info of the QA test would be incorporated on the documentation of upgrade options? Should i propose this on some list?

I think the qa testcase should be made simpler and clearer, if possible. And then migrate it to a quickdoc including relevant screenshots that help guide the user. Then that quickdoc can be referenced in any upgrade documentation.

If you have suggestions on simplifying the QA test case or just noting any nitpicks where it wasn’t clear or too wordy or overly technical - you can reply in this Ask Fedora topic, and I can modify the wiki accordingly.

Anyone can contribute to Fedora Docs. The format used for Fedora documentation, including Quick Docs, is asciidoc.