The Operating System Resource Center at http://www.nondot.org/sabre/os/articles/ has a wealth of information on various operating system techniques, including file systems.
Another important source of information is the Linux kernel source,
File system drivers are in the
fs directory, but
many include files defining structures are actually in
include/linux. The RAID and LVM code lives in
All code for reading various partition maps is in
The Linux kernel even contains some format detection code in
init/do_mounts.c, used in mounting an initial
Other Unix kernels are also available in source code, like Darwin (the BSD-based kernel used in Mac OS X) at http://www.opensource.apple.com/darwinsource/ and the free BSD derivatives FreeBSD (http://www.freebsd.org/), OpenBSD (http://www.openbsd.org/), and NetBSD (http://www.netbsd.org/).