btrfs

As of version 5.0 of the Linux kernel, Btrfs implements the following features:

Mostly self-healing in some configurations due to the nature of copy-on-write Online defragmentation and an autodefrag mount option Online volume growth and shrinking Online block device addition and removal Online balancing (movement of objects between block devices to balance load) Offline filesystem check Online data scrubbing for finding errors and automatically fixing them for files with redundant copies RAID 0, RAID 1, and RAID 10 Subvolumes (one or more separately mountable filesystem roots within each disk partition) Transparent compression via zlib, LZO and (since 4.14) ZSTD, configurable per file or volume Atomic writable (via copy-on-write) or read-only Snapshots of subvolumes File cloning (copy-on-write on individual files) via cp --reflink <source file> <destination file>[39] Checksums on data and metadata (CRC-32C) In-place conversion from ext3/4 to Btrfs (with rollback). This feature regressed around btrfs-progs version 4.0, rewritten from scratch in 4.6. Union mounting of read-only storage, known as file system seeding (read-only storage used as a copy-on-write backing for a writable Btrfs) Block discard (reclaims space on some virtualized setups and improves wear leveling on SSDs with TRIM) Send/receive (saving diffs between snapshots to a binary stream) Incremental backup Out-of-band data deduplication (requires userspace tools) Ability to handle swap files and swap partitions