xraid partition help

[TA2001]

Greetings..

I have a xserver raid set with 1-TB in each side.

They are configured in raid-5.

Here is the problem... I want to make a strip set
out of them or combine them in such a way to get

near a 2-TB partition.

using stripe option:
[drag:/] root# /sbin/newfs_hfs -v drag-a /dev/disk1
Initialized /dev/rdisk1 as a 1035 GB HFS Plus volume

[drag:/] root# /sbin/newfs_hfs -v drag-b /dev/disk2
Initialized /dev/rdisk2 as a 1035 GB HFS Plus volume

[drag:/] root# diskutil createRAID stripe newsba HFS /dev/disk1 /dev/disk2

## I get this result ##
[drag:/] root# df -lk
Filesystem 1K-blocks Used Avail Capacity Mounted on
/dev/disk0s2 58615668 2424268 55935400 4% /
/dev/disk3 23722584 1448 23721136 0% /Volumes/newsba

my disk3 is 23 Gig ??


#####################################################

now using mirror.

drag:/] root# /sbin/newfs_hfs -v drag-a /dev/disk1
Initialized /dev/rdisk1 as a 1035 GB HFS Plus volume
[drag:/] root# /sbin/newfs_hfs -v drag-b /dev/disk2
Initialized /dev/rdisk2 as a 1035 GB HFS Plus volume
[drag:/] root# diskutil createRAID mirror newsba HFS /dev/disk1 /dev/disk2


** result ** 1.08 TB expected.. its a mirror.

Filesystem 1K-blocks Used Avail Capacity Mounted on
/dev/disk0s2 58615668 2424244 55935424 4% /
/dev/disk3 1085570710 49695 1085521015 0% /Volumes/newsba


Now what can I do go get the strip to work and get me
closer to 2-TB on that partition..

Thanks in advance..

Terry