Berkeley Fast File System

In computing, the Berkeley Fast File System (or FFS) is a file system used mostly by BSD-derivative Unix variants. It is a distant descendant of the original filesystem used by Version 7 Unix. UFS 1 and 2 are, in turn, derivatives of the original FFS.

In modern BSDs, the implementation of UFS1 and UFS2 is split into two layers - an upper layer that provides the directory structure and supports metadata (permissions, ownership, etc.) in the inode structure, and lower layers that provide data containers implemented as inodes. This was done to support both the traditional FFS and the LFS log-structured file system with common code for common functions. The upper layer is called "UFS", and the lower layers are called "FFS" and "LFS". However, elsewhere it is stated that FFS sits on top of UFS (1 or 2) and provides directory structure information, and a variety of disk access optimizations, while UFS (and UFS2) define on-disk data layout.

See also

• Comparison of file systems

External links

• Marshall Kirk McKusick, William N. Joy, Samuel J. Leffler and Robert S. Fabry. A Fast File System for UNIX. Transactions on Computer Systems, vol. 2, num. 3, Aug. 1984, pp. 181-197.
• The Linux Documentation Project's Filesystems HOWTO: FFS.
• Little UFS2 FAQ: What is the difference between UFS and FFS?
• A Fast File System for UNIX*, Marshall Kirk McKusick, William N. Joy , Samuel J. Leffler, Robert S. Fabry, Computer Systems Research Group Computer Science Division Department of Electrical Engineering and Computer Science University of California, Berkeley Berkeley, CA 94720