btrfs

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