Identity

Type: Kernel built-in filesystem (no loadable module needed on most distros)
CLI tool: btrfs (subcommands: filesystem, subvolume, balance, scrub, device, quota, qgroup, check, defragment, rescue)
Distro install: apt install btrfs-progs / dnf install btrfs-progs
Filesystem created at: mkfs.btrfs time (not mounted separately)
Kernel version matters: Significant stability improvements landed between 4.x and 6.x. Older kernels have known bugs — especially with RAID-5/6 and balance operations.

Key Operations

Operation	Command
Show filesystems	`btrfs filesystem show`
Filesystem usage (detailed)	`btrfs filesystem usage /mount`
List subvolumes	`btrfs subvolume list /mount`
Create subvolume	`btrfs subvolume create /mount/name`
Delete subvolume	`btrfs subvolume delete /mount/name`
Create read-write snapshot	`btrfs subvolume snapshot /mount/src /mount/dst`
Create read-only snapshot	`btrfs subvolume snapshot -r /mount/src /mount/dst`