Marshall Kirk McKusick

Marshall Kirk McKusick (born January 19, 1954) is a computer scientist, known for his extensive work on BSD UNIX, from the 1980s to FreeBSD in the present day. He was president of the USENIX Association from 1990 to 1992 and again from 2002 to 2004, and still serves on the board. He is on the editorial board of ACM Queue Magazine. He is known to friends and colleagues as "Kirk".

McKusick received his B.S. in electrical engineering from Cornell University, and two M.S. degrees (in 1979 and 1980 respectively) and a Ph.D. in computer science from the University of California, Berkeley in 1984.

McKusick lives in California with Eric Allman, his partner since graduate school, whom he married in October, 2013.

BSD
McKusick started with BSD by virtue of the fact that he shared an office at Berkeley with Bill Joy, who spearheaded the beginnings of the BSD system.

Some of his largest contributions to BSD have been to the file system. He helped to design the original Berkeley Fast File System (FFS). In the late 1990s, he implemented soft updates, an alternative approach to maintaining disk integrity after a crash or power outage, in FFS, and a revised version of Unix File System (UFS) known as "UFS2". The magic number used in the UFS2 super block structure reflects McKusick's birth date:  (as found in   on FreeBSD systems). It is included as an easter egg.

He was also primarily responsible for creating the complementary features of filesystem snapshots and background  (file system check and repair), which both integrate closely with soft updates. After the filesystem snapshot, the filesystem can be brought up immediately after a power outage, and  can run as a background process.

The Design and Implementation series of books are regarded as very high-quality works in computer science. They have been influential in the development of the BSD descendants. The BSD Daemon, often used to identify BSD, is copyrighted by Marshall Kirk McKusick.