Установщик не знает о томах BTRFS, но есть обходной путь.
Это адаптация ответа от Ask Ubuntu . Поскольку я лишь случайный пользователь Ubuntu, а не BTRFS, лучше проверьте мой ответ.
- Do the server setup as usual, at the *Finish installation* step, select **Go Back** and **Execute a shell**. - List all your target file systems: mount | grep target /dev/dm-0 on /target type btrfs (rw,noatime,space_cache,subvolid=257,subvol=/@) /dev/dm-0 on /target/home type btrfs (rw,noatime,space_cache,subvolid=258,subvol=/@home) proc on /target/proc type proc (rw,nosuid,nodev,noexec,relatime) devtmpfs on /target/dev type devtmpfs (rw,nosuid,relatime,size=475608k,nr_inodes=118902,mode=755) - Take a note of the BTRFS device, in this example `/dev/dm-0`. - Now un-mount all of your mounted file systems. umount /target/dev umount /target/proc umount /target/boot/efi umount /target/home umount /target/ - Mount your **flat** btrfs filesystem : cd /tmp mkdir work mount /dev/dm-0 work cd work - Verify the mount is correct (should show `@` and `@home`): ls @ @home - Create your additional subvolumes (`@tmp`, `@var`, `@var-log`) btrfs subvolume create @tmp btrfs subvolume create @var btrfs subvolume create @var-log - Move the data mv @/var/log/* @var-log/ mv @/var/* @var/ # Remove data from tmp rm @/tmp/* @/tmp/.* # For 18.04, remove the swapfile since it won't work on btrfs rm @/swapfile - Add the new subvolumes to fstab, the device part may be different than the previous mount command, copy the device part from the already existing mount points. ... /dev/mapper/root-root / btrfs noatime,subvol=@ 0 1 /dev/mapper/root-root /home btrfs noatime,subvol=@home 0 2 /dev/mapper/root-root /var btrfs noatime,subvol=@var 0 2 /dev/mapper/root-root /var/log btrfs noatime,subvol=@var-log 0 2 - Unmount cd /tmp umount work sync - `exit`, then **Finish the installation** - Install and configure [snapper](http://snapper.io), a great tool for automatizing snapshots.