# Create a btrfs file system on /dev/sdb, /dev/sdc, and /dev/sdd
mkfs.btrfs /dev/sdb /dev/sdc /dev/sdd

# btrfs with just one hard drive, metadata not redundant
# (this is dangerous: if your metadata is lost, your data is lost as well)
mkfs.btrfs -m single /dev/sdb

# data to be redundant and metadata to be non-redundant:
mkfs.btrfs -m raid0 -d raid1 /dev/sdb /dev/sdc /dev/sdd

# both data and metadata to be redundant
mkfs.btrfs -d raid1 /dev/sdb /dev/sdc /dev/sdd

# To get a list of all btrfs file systems
btrfs filesystem show

# detailed df for a filesystem (mounted in /mnt)
btrfs filesystem df /mnt

# resize btrfs online (-2g decreases, +2g increases)
btrfs filesystem resize -2g /mnt

# use maximum space
btrfs filesystem resize max /mnt

# add new device to a filesystem
btrfs device add /dev/sdf /mnt

# remove devices from a filesystem
btrfs device delete missing /mnt

# create the subvolume /mnt/sv1 in the /mnt volume
btrfs subvolume create /mnt/sv1

# list subvolumes
btrfs subvolume list /mnt

# mount subvolume without mounting the main filesystem
mount -o subvol=sv1 /dev/sdb /mnt

# delete subvolume
btrfs subvolume delete /mnt/sv1

# taking snapshot of a subvolume
btrfs subvolume snapshot /mnt/sv1 /mnt/sv1_snapshot

# taking snapshot of a file (copy file by reference)
cp --reflink /mnt/sv1/test1 /mnt/sv1/test3

# convert ext3/ext4 to btrfs
btrfs-convert /dev/sdb1

# convert btrfs to ext3/ext4
btrfs-convert -r /dev/sdb1