Converting to BtrFS — Episode 1

Last Updated on November 19, 2025 by David Both

I’ve previously written about why I won’t use the BtrFS filesystem, and the fact that it’s become the only filesystem available for new installations of Fedora starting with Fedora 43. In that second article I said I’d keep you all updated on my efforts to migrate at least some of my systems to BtrFS.

It’s not going well.

Converting existing filesystems

Since I’ve had problems with BtrFS in the past, I decided that my first attempt at converting an LVM/EXT4 filesystem to BtrFS would be on a virtual machine which I could easily roll back to a previous snapshot. It’s much better to be safe than sorry and there’s no way I’d start on my primary workstation, or any other of my real systems.

I booted my virtual machine to a Live ISO image of Fedora and started with the recommended fsck command to ensure the /home filesystem I chose for this first attempt was clean. Then, using the btrfs-convert command, I attempted the conversion. I tried to mount the /home filesystem on /mnt on the Live system but that failed. The filesystem also failed to mount on reboot and that forced the virtual machine into maintenance mode.

Reverting to the snapshot, I tried again — and again — and — you get the idea. I changed something in my command each time I tried, but the end result was always the same. To be clear, the man page for the btrfs-convert command did indicate that the conversion would not always work. One can always hope.

I’ve been unable to locate any specific information about converting an EXT4 filesystem on a logical volume, and I think that’s the problem. So I tried again by creating a new virtual drive for the virtual machine and configuring part of it as EXT4 on a raw partition with no LVM and that worked fine. If you try this, be sure to change the entry for the filesystem mount in /etc/fstab.

Next step

Since all my systems use logical volume management (LVM) this conversion tool won’t work for me. It seems I’ll need to do complete reinstallations.

My problem now is that I need to convert a system that I use regularly in order to fully prove to myself that BtrFS might be ready for use in my lab. But I’m still not going to go all-in until I’ve converted a lesser used system for preliminary testing.

Stay tuned for the next episode.