If you need to create partitions on a disk (or raid volume) which is larger than 1Tb you will need to use parted and set the disk label to GPT. This is an example session creating 2 1Tb partitions on a 2Tb raid5 volume:

[root@sn-b03 parted]# parted /dev/sdb
GNU Parted 1.6.9
Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 Free Software Foundation,
Inc.

This program is free software, covered by the GNU General Public License.

This program is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
License for more details.

Using /dev/sdb
Information: The operating system thinks the geometry on /dev/sdb is 291775/255/63.
Therefore, cylinder 1024 ends at 8032.499M.
(parted) mklabel gpt
(parted) mkpart primary 0 1048576
(parted) mkpart primary 1048577 2097152
(parted) p
Disk geometry for /dev/sdb: 0.000-2288754.000 megabytes
Disk label type: gpt
Minor    Start       End     Filesystem  Name                  Flags
1          0.017 -1048576.000  ext3
2     -1048575.000      0.000
(parted) quit
Information: Don't forget to update /etc/fstab, if necessary.

[root@sn-b03 parted]#