I just read the somewhat old, but still very useful How To Convert An ext3/ext4 Root File System To btrfs On Ubuntu 12.10 and tried part 2 in an Ubuntu 20.04 VPS. Besides from some minor details, it works quite well, apart from the `find /mnt -xdev -delete` command, as it removes my `@home` folder. I guess I'm doing something wrong, but I have no clue what. On my experimental VPS the /home directory is empty, so no problem there. But before trying this on a production server, I would like to solve this. Insightful suggestions are very welcome.
run the command without the delete option first, ie `find /mnt -xdev' and see what it finds. then tailor the command to only delete what you want deleted.