This module allows you to create slices and partitions on disks attached to a FreeBSD system. There are three levels of objects that have to be taken managed on a FreeBSD system, compared to only two on Linux :

Disks
  A disk is a physical drive attached to the system, either internally or via an external bus like USB. Disks can be either SCSI or IDE.

Slices
  A slice is part of a disk whose extents are stored in the disk's partition table. On a Linux or Windows system these are called "Partitions".

Partition
  A slice can contain up to four partitions, each of which can contain either a filesystem or be used for virtual memory.

After adding a new disk to a system, you will need to first add a slice to it (or change the existing slice type to BSD/386), and then add a partition of type 4.2BSD within that slice.

The sizes and ranges of disks, slices and partitions are all measured in blocks, which are typically 512 bytes in size.