Strange problem with Device Mapper

["Paul Rolland" <rol@as2917.net>]

Hello,

I've a machine that has been installed with Intel Soft Raid on top
of 2 SATA disks.
I'm trying to have this work as a RAID-1 array. 
Bios configuration has been done, using 128K chunk, and the kernel
(2.6.20.7) sees perfectly /dev/mapper/isw_xxxxxxxx_RAID1

But, I'm facing two problems :
1 - If i try to create partitions on this device, it does fail (the 
    values are not interpreted correctly)

2 - To avoid 1), I stop the RAID array (dmraid -an), then I do create
    exactly the same partition set on /dev/sda, and /dev/sdb, and
    then I reactivate RAID (dmraid -ay).
    This allows me to see all the /dev/mapper/isw_xxxxxxx_RAID1p1, p2, ...
    But, running fsck -t ext2 /dev/mapper/isw_xxxxxxx_RAID1p1
    ends in a lock when the partition is larger than 10Go (well, it is
    Ok on the 10Go one, and it locks on the 100Go).
    Not a real hardlock, I still can switch to a new VC, but it's not
    more possible to start a new command or to stop fsck.

Should I do everything on the physical disks before activating RAID ?
Is it a normal behavior ?

BTW, I also noticed that such a device doesn't support BLKRRPART ioctl...
So it is possible that what I'm doing is wrong...

Any idea ?

Regards,
Paul