Kernel file system support under RHEL

[Chiu, PCM (Peter)]

We have just recently acquired a few 24 x 400GB SATA servers with
3Com 9500S-12 controllers.  The 24 drives are configured into 2 x Raid 5
sets
with the 9500S controllers, so each RAID set should have a capacity of
4TB.

Under RHEL AS 3 update 3, the RAIDs are recognised as sda and sdb
devices
with 2TB capacity each, as opposed to 4.

If I then mount RHEL AS 4, "fdisk -l" shows sda and sdb being 4TB each,
but
mke2fs -j /dev/sda or sdb will only make a 1.8GB file system on each
device.
(1.8GB is not a typing mistake.)

I tried to check the kernel with make menuconfig, but I cannot find a
suitable
option to specify a larger file system.

Is this an oversight or a bug? 
The feature page on RedHat clearly states the support of 8TB under RHEL
AS 4.
Did try to check RedHat knowledge database and bugzilla but cannot
locate any reference.

By the way, the processors are dual AMD 248 with 4GB RAM, and I did
select
the x86-64 versions of the RHEL.

Any suggestion?  

Thanks.