btrfs.md

btrfs File system setup

First create the partition using a tool like fdisk or gdisk.

After creating the partition, format it with btrfs:

mkfs.btrfs /dev/sdXn

Mount the partition:

mount /dev/sdXn /mnt

Create subvolumes:

btrfs subvolume create /mnt/@
btrfs subvolume create /mnt/@home
btrfs subvolume create /mnt/@snapshots
btrfs subvolume create /mnt/@vm_disks

Unmount the partition:

umount /mnt

And mount the subvolumes using zstd compression:

# Root subvolume
mount -o subvol=@,compress=zstd /dev/sdXn /mnt
# Home
mkdir -p /mnt/home
mount -o subvol=@home,compress=zstd /dev/sdXn /mnt/home
# Snapshots
mkdir -p /mnt/.snapshots
mount -o subvol=@snapshots,compress=zstd /dev/sdXn /mnt/.snapshots
# To exclude qemu images from snapshots
mkdir -p /mnt/var/lib/libvirt/images
mount -o subvol=@vm_disks,compress=zstd /dev/sdXn /mnt/var/lib/libvirt/images

Finally if using dracut and an encrypted LVM, add the following cmdline:

kernel_cmdline="rd.luks.uuid=luks-<uuid> rd.lvm.lv=vg/root root=/dev/mapper/vg-root rootfstype=btrfs rootflags=subvol=@,rw,relatime,compress=zstd"

Where <uuid> is the UUID of the vg/root partition.