Bonnie, originally written in 1989-90 when I was in the employ of the Oxford English Dictionary project, is a C-language benchmark measuring the performance of Unix filesystems. There is some discussion at http://www.textuality.com/bonnie.

There is another version of Bonnie, Bonnie++, developed by Russell Coker, which appears both at http://www.coker.com.au/bonnie++/ and http://sourceforge.net/projects/bonnie/ - it is in C++ and includes many tests that Bonnie doesn't. It works around the 32-bit limit by scattering the data across multiple files.

Bonnie64 is a slight rev of the original Bonnie, designed to run on 64-bit computers. Also the output is a bit more useful since it reports in M/sec rather than K/sec. Its construction is discussed at my blog see http://www.tbray.org/ongoing/When/200x/2004/11/16/Bonnie64 and http://www.tbray.org/ongoing/When/200x/2005/12/07/ZFS