The command line is the easiest way to make dedicated disks, and the worst way to make compatibility disks. The command-line fdisk utility requires higher math skills and an in-depth understanding of the slice table, which is more than most people want to deal with. Use sysinstall for compatibility disks, as described below.
Start sysinstall as root by typing
from the command prompt.Select Index.
Select Partition.
Select the disk to edit with arrow keys and SPACE.
If you are using this entire disk for FreeBSD, select A.
When asked:
Do you want to do this with a true partition entry so as to remain cooperative with any future possible operating systems on the drive(s)?
Select Write.
When asked to install the boot manager, select None with SPACE then hit ENTER for OK.
Quit the FDISK Editor.
You will be asked about the boot manager, select None again.
Select Label from the Index menu.
Label as desired. For a single partition, accept the default size, type filesystem, and a mountpoint (which is not used).
The filesystem will be newfs'd for you, unless you select otherwise (for new partitions you will want to do this!). You will get the error:
Ignore.Exit out by repeatedly pressing ESCAPE.
Your new disk is now ready for use.