“Generally, file systems are not considered ‘sexy’. When a young programmer wants to do something really cool, his or her first thought is generally not ‘dude, two words… File system’. However, I am what is politely termed ‘different’. I find file systems very interesting and they have seldom been more so than they are right now. Hans Reiser is working on getting Reiser4 integrated into the Linux kernel, the BSDs are working on getting a journaled file system together, and Sun Microsystems just recently released a beta of ZFS into OpenSolaris. This is an excellent time to be me. This article will be on file system design and specifically the new file systems that are just appearing. We will start with the basics, UFS/FFS, and then proceed to our first modern file system, XFS.