Preliminary:
- Kernel with btrfs support (located at
/lib/modules/$(uname -r)/kernel/fs/btrfs/btrfs.ko) - Userspace tools:
apt-get install btrfs-tools(mainly for filesystem creation, conversion, etc.)
In order to create filesystem on device (even not partitioned one):
mkfs.btrfs /dev/sdb /dev/sdc /dev/sdd