Paket:

• Debian: btrfs-progs

ext? nach btrfs konvertieren:

man btrfs-convert

oder besser:

Dateisystem anlegen und mounten:

mkfs.btrfs /dev/sda2
btrfs filesystem show
mkdir /mnt/btrfs
mount /dev/sda2 /mnt/btrfs
cd /mnt/btrfs

Beispieldaten hinein kopieren:

time cp -a /usr/share/ .

Daten komprimieren:

btrfs filesystem df -h share/

→ Data, single: total=2.01GiB, used=1.53GiB

btrfs filesystem defragment -czstd -r share/
btrfs filesystem df -h share/

→ Data, single: total=3.01GiB, used=740.17MiB

Informationen über das top-level Subvolume anzeigen:

btrfs subvolume show .

→ Subvolume ID: 5

btrfs subvolume list .

→ noch keine Subvolumes

Subvolume anlegen und Daten hinein verschieben:

btrfs subvolume create subvol1
btrfs subvolume list .
btrfs subvolume show subvol1

→ Subvolume ID: 256 → Parent ID: 5

time mv ./share/ ./subvol1/

Subvolume umbenennen:

mv subvol1/ subvol2

Subvolume (erneut) mounten:

mkdir /mnt/subvol2
mount -o subvol=/subvol2 /dev/sda2 /mnt/subvol2  

Snapshot erstellen:

time btrfs subvolume snapshot subvol2 snap1
btrfs subvolume list .
btrfs subvolume show snap1

→ Subvolume ID: 257 → Parent ID: 5

Read-only Snapshot erstellen:

btrfs subvolume snapshot -r subvol2 snap_ro1

btrfs filesystem df -h .
btrfs filesystem du -s --human-readable .
du -sh .
du -shx .
btrfs filesystem du -s --human-readable subvol2
du -sh subvol2
btrfs filesystem du -s --human-readable snap1

cd /mnt/btrfs

Snapshot des root-Volumes erstellen:

btrfs subvolume snapshot . 2025011300

Daten (nicht Subvolumes!) aus root-Volume löschen:

ls 2025011300 | xargs echo rm -rf

→ prüfen, das da keine Verzeichnisse mit verschachtelten Subvolumes enthalten sind

ls 2025011300 | xargs rm -rf
btrfs subvolume show 2025011300

→ Subvolume ID kopieren, z.B. 258

btrfs subvolume set-default 256 2025011300/

testen:

ls
cd ..
umount btrfs
mount btrfs
ls btrfs

mkdir /mnt/subvol
mount -o subvolid=5 /dev/sda2 /mnt/subvol

++++ SuSE default root layout | SuSE default:

mkfs.btrfs ${BOOT_DEVICE}2
uuid=$(lsblk -n -o uuid ${BOOT_DEVICE}2)

mkdir $target
mount UUID="$uuid" $target || exit

btrfs subvolume create ${target%/}/@
btrfs subvolume create ${target%/}/@/.snapshots
mkdir -p               ${target%/}/@/.snapshots/1
btrfs subvolume create ${target%/}/@/.snapshots/1/snapshot
mkdir -p               ${target%/}/@/boot/grub2
btrfs subvolume create ${target%/}/@/boot/grub2/i386-pc
btrfs subvolume create ${target%/}/@/boot/grub2/x86_64-efi
btrfs subvolume create ${target%/}/@/opt
btrfs subvolume create ${target%/}/@/srv
btrfs subvolume create ${target%/}/@/tmp
mkdir -p               ${target%/}/@/usr
btrfs subvolume create ${target%/}/@/usr/local
mkdir -p               ${target%/}/@/var
btrfs subvolume create ${target%/}/@/var/crash
mkdir -p               ${target%/}/@/var/lib/libvirt
btrfs subvolume create ${target%/}/@/var/lib/libvirt/images
btrfs subvolume create ${target%/}/@/var/lib/mailman
btrfs subvolume create ${target%/}/@/var/lib/mariadb
btrfs subvolume create ${target%/}/@/var/lib/mysql
btrfs subvolume create ${target%/}/@/var/lib/named
btrfs subvolume create ${target%/}/@/var/lib/pgsql
btrfs subvolume create ${target%/}/@/var/log
btrfs subvolume create ${target%/}/@/var/opt
btrfs subvolume create ${target%/}/@/var/spool
btrfs subvolume create ${target%/}/@/var/tmp

subvolid=$(btrfs subvolume show $target/@/.snapshots/1/snapshot | sed -rn 's/.*Object ID:\s+//p')
btrfs subvolume set-default "$subvolid" "$target"

++++