OpenZFS File System

OpenZFS is an advanced file system and logical volume manager that provides data integrity verification, snapshotting, replication, and high-capacity storage management across multiple operating systems. Originally developed as ZFS for Solaris by Sun Microsystems (led by Jeff Bonwick and Bill Moore) in 2001, open-sourced in 2005, and continued as OpenZFS after Oracle's acquisition, the project supports Linux, FreeBSD, and macOS. Key features include: copy-on-write (all writes create new data blocks rather than overwriting existing data, ensuring atomic updates and crash consistency without fsck), data integrity (end-to-end checksumming on every block with automatic healing using redundant data from mirrors or RAID-Z), RAID-Z (software RAID levels 1, 2, and 3 with variable stripe sizes eliminating the write hole vulnerability of hardware RAID), snapshots and clones (instant space-efficient filesystem snapshots for backup and recovery, with writable clones for forking datasets), data compression (LZ4, ZSTD, GZIP, and ZLE compression with early-abort for incompressible data, saving space with negligible CPU overhead), deduplication (block-level deduplication with optional verification for eliminating duplicate data blocks), send and receive (incremental and full dataset replication over network or pipe for efficient backup and disaster recovery), ARC and L2ARC (Adaptive Replacement Cache in RAM for hot data and L2ARC on SSD for warm data caching), ZIL and SLOG (ZFS Intent Log on separate SSD for synchronous write acceleration), encryption (native dataset-level encryption with AES-256-GCM, key rotation, and raw send for encrypted backups), datasets and properties (hierarchical datasets with inheritance of compression, checksum, quota, reservation, and mount point properties), and scrubs (online data integrity checking that verifies all block checksums and repairs detected errors).