Disks are getting bigger, but so are data storage requirements. Often you will find you want a file system that is bigger than the disks you have available. Admittedly, this problem is not as acute as it was ten years ago, but it still exists. Some systems have solved this by creating an abstract device which stores its data on a number of disks.
This, and other documents, can be downloaded from ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/.
For questions about FreeBSD, read the documentation before contacting <questions@FreeBSD.org>.
For questions about this documentation, e-mail <doc@FreeBSD.org>.