Several varieties of partitioning programs have been adapted by Debian developers to work on various types of hard disks and computer architectures. Following is a list of the program(s) applicable for your architecture.
Recommended partitioning tool in Debian. This Swiss army knife can also resize partitions, create filesystems and assign them to the mountpoints.
The original Linux disk partitioner, good for gurus.
Be careful if you have existing FreeBSD partitions on your machine. The installation kernels include support for these partitions, but the way that fdisk represents them (or not) can make the device names differ. See the Linux+FreeBSD HOWTO.
One of these programs will be run by default when you select(or similar). It may be possible to use a different partitioning tool from the command line on VT2, but this is not recommended.
Make sure you create a “Sun disk label” on your boot disk. This is the only kind of partition scheme that the OpenBoot PROM understands, and so it's the only scheme from which you can boot. The s key is used in fdisk to create Sun disk labels.
Furthermore, on SPARC disks, make sure your first partition on your boot disk starts at cylinder 0. While this is required, it also means that the first partition will contain the partition table and the boot block, which are the first two sectors of the disk. You must not put swap on the first partition of the boot drive, since swap partitions do not preserve the first few sectors of the partition. You can put Ext2 or UFS partitions there; these will leave the partition table and the boot block alone.
It is also advised that the third partition should be of type “Whole disk” (type 5), and contain the entire disk (from the first cylinder to the last). This is simply a convention of Sun disk labels, and helps the SILO boot loader keep its bearings.