ufs

UFS, or Unix File System, is a family of file systems used by Unix and Unix-like operating systems. It originated with early Unix releases and became the standard file system in several BSD variants. In the BSD lineage, the Unix File System was extended by the Berkeley Fast File System (FFS) in the 1980s to improve performance and reliability. FFS introduced techniques such as cylinder groups, improved block allocation, and faster disk I/O, and is often considered the modern successor to the original UFS design. Some systems still refer to their non-FFS variants as UFS, while others distinguish UFS from FFS.

Technically, UFS designs store metadata in inodes and manage data in fixed-size blocks. Cylinder groups partition the disk into flexible regions to reduce disk seeks and improve locality. Common features include directories, hierarchical permissions, symbolic links, and support for large files and volumes in later variants. UFS2, the successor used on some BSDs, adds support for larger files, larger filesystems, and improved metadata handling; some features like soft updates were implemented to increase consistency without full journaling.

Implementation and usage: UFS is implemented in several BSD derivatives, including FreeBSD, NetBSD, and OpenBSD, as well as legacy SunOS/Solaris environments. While ZFS and other modern file systems have become common in new deployments, UFS remains available for compatibility with older systems and software.

See also: Berkeley Fast File System, soft updates, ZFS.