parted/mkpart to create an ext3 partition

[ezshop]

Hi,
We have a server class machine pre-configured by Dell running only Linux.
Windows Clients (through a program)read-write from/to a directory/filesystem 
on this server.
We have 3 HW-Raid Controlled disks installed, each around 180GB. (Raid5 - 
hence, roughly 2/3 of 3x180 should be available)
We realized that a lot of space on the disk(s) is not usable (not 
partitioned/mounted) We want to create an ext3 partition/filesystem on this 
disk collection and use "/data" to store large number of files via mounting.

I read that I have to use mkpart to create an ext3 filesystem.
Either I'm doing something wrong or else. your help will be greatly 
appreciated.

some outputs;

address@hidden root]# df -k
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda7              2063504    352996   1605688  19% /
/dev/sda3               194449     11311    173098   7% /boot
none                   1030776         0   1030776   0% /dev/shm
/dev/sda8              1035660     32920    950132   4% /tmp
/dev/sda5             10072456   3084288   6476500  33% /usr
/dev/sda6             10072456    125128   9435660   2% /var
/dev/sda2              2585332     35528   2418476   2% /home

address@hidden root]# fdisk -l 

Disk /dev/sda: 293.5 GB, 293597741056 bytes
255 heads, 63 sectors/track, 35694 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/sda1             1         5     40131   de  Dell Utility
/dev/sda2             6       332   2626627+  83  Linux
/dev/sda3   *       333       357    200812+  83  Linux
/dev/sda4           358     35694 283844452+   f  Win95 Ext'd (LBA)
/dev/sda5           358      1631  10233373+  83  Linux
/dev/sda6          1632      2905  10233373+  83  Linux
/dev/sda7          2906      3166   2096451   83  Linux
/dev/sda8          3167      3297   1052226   83  Linux
/dev/sda9          3298      3551   2040223+  82  Linux swap


address@hidden root]# parted /dev/sda4
GNU Parted 1.6.3
Copyright (C) 1998, 1999, 2000, 2001, 2002 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/sda4

===================

Whatever I execute from this moment on, I get the following message;

Error: Can't have a partition outside the disk!

sda5/6/7/8/9 are all within the range of sda4 (Start/End) so we were hoping 
to create another one to continue using available space that way -  but I 
don't even know what's special about sda4 and how we should be doing this.

Should I not use /dev/sda4 to begin with ??

many thanks

/Ersin Zeybek