A Brief History of the BSD Fast Filesystem by Marshall Kirk McKusick

Marshall Kirk McKusick traces the evolution of filesystem design from early disk-geometry optimizations to modern contiguous layouts and soft updates.

This talk provides a taxonomy of filesystem and storage development from 1979 to the present with the BSD Fast Filesystem as its focus. It describes the early performance work done by increasing the disk block size and by being aware of the disk geometry and using that knowledge to optimize rotational layout. With the abstraction of the geometry in the late 1980's and the ability of the hardware to cache and handle multiple requests, filesystems performance ceased trying to track geometry and instead sought to maximize performance by doing contiguous file layout. Small file performance was optimized through the use of techniques such as journaling and soft updates. By the late 1990's, filesystems had to be redesigned to handle the ever growing disk capacities. The addition of snapshots allowed for faster and more frequent backups. The increasingly harsh environment of the Internet required greater data protection provided by access-control lists and mandatory-access controls. The paper concludes with a discussion of the addition of symmetric multi-processing support needed to utilize all the CPUs found in the increasingly ubiquitous multi-core processors. Dr. Marshall Kirk McKusick writes books and articles, teaches classes on UNIX- and BSD-related subjects, and provides expert-witness testimony on software patent, trade secret, and copyright issues particularly those related to operating systems and filesystems. While at the University of California at Berkeley, he implemented the 4.2BSD fast filesystem and was the Research Computer Scientist at the Berkeley Computer Systems Research Group (CSRG) overseeing the development and release of 4.3BSD and 4.4BSD. His particular areas of interest are the virtual-memory system and the filesystem. He earned his undergraduate degree in electrical engineering from Cornell University and did his graduate work at the University of California at Berkeley, where he received master's degrees in computer science and business administration and a doctoral degree in computer science. He has twice been president of the board of the Usenix Association, is currently a member of the editorial board of ACM's Queue magazine, and is a member of the Usenix Association, ACM, and IEEE. In his spare time, he enjoys swimming, scuba diving, and wine collecting. The wine is stored in a specially constructed wine cellar (accessible from the Web at mckusick.com/~mckusick/) in the basement of the house that he shares with Eric Allman, his domestic partner of 28-and-some-odd years.