btrfs
also: B-tree filesystem, btrfs filesystem
Btrfs (B-tree filesystem) is a modern Linux filesystem that provides advanced features like snapshots, subvolumes, and built-in RAID support, designed to replace ext4 with better scalability and reliability.
Btrfs is a copy-on-write (CoW) filesystem developed collaboratively by multiple Linux vendors. It uses B-tree data structures to organize metadata, enabling efficient management of large storage pools and complex operations.
Key features include instant snapshots (point-in-time copies that share data), subvolumes (independent filesystem hierarchies), transparent compression, checksumming for data integrity, and native RAID support (levels 0, 1, 10) without requiring mdadm. For example, you can create a snapshot with btrfs subvolume snapshot /mnt/data /mnt/data-backup that takes negligible space initially.
While mature and widely supported, btrfs remains somewhat less stable than ext4 in production environments and has different performance characteristics. It's particularly useful for systems requiring frequent backups, large storage arrays, or dynamic capacity management.