@Skinny
Take a look at
FreeBSD's Handbook Storage section:
http://freebsd.org/handbook/disks.html
... and compare it to
Absolute FreeBSD, 2nd Edition example
Chapter 8: Disks and Filesystems:
http://www.tinker.tv/download/afreebsd2_ch8.pdf (this is officially available chapter, link is from
http://nostarch.com/abs_bsd2.htm site)
That should give You the idea what are the differences.
Of course its a FreeBSD example, not OpenBSD one, but as author of both of these books is the same proposed comparison should be valid.