BIOS say ''rebuild" but drive seems to keep being desynchronized

Hello,

I set up a RAID1 array on a sunfire x2200 (nvidia raid controller), 
running Debian Etch, dmraid version 1.0.0.rc13-2, kernel 2.6.18.
I replaced one drive (testing purpose) and asked the controller to 
rebuild the array with this drive (through the nvidia raid bios).

However, some days later, the BIOS controller still say "status: rebuild".

But the two drives are still desynchronized:

sunfirex2200:~# fdisk -l /dev/sda
Disk /dev/sda: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1        1217     9775521   83  Linux
/dev/sda2            1218        1461     1959930   82  Linux swap / Solaris
/dev/sda3            1462       27479   208989585   83  Linux
/dev/sda4           27480       29912    19543072+  83  Linux

sunfirex2200:~# fdisk -l /dev/sdb
Disk /dev/sdb: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk /dev/sdb doesn't contain a valid partition table

sunfirex2200:~# dmraid -tay
nvidia_abgjajeh: 0 488397166 mirror core 2 131072 nosync 2 /dev/sda 0 
/dev/sdb 0
nvidia_abgjajeh1: 0 19551042 linear /dev/mapper/nvidia_abgjajeh 63
nvidia_abgjajeh2: 0 3919860 linear /dev/mapper/nvidia_abgjajeh 19551105
nvidia_abgjajeh3: 0 417979170 linear /dev/mapper/nvidia_abgjajeh 23470965
nvidia_abgjajeh4: 0 39086145 linear /dev/mapper/nvidia_abgjajeh 441450135

Could you tell me what's happening ?

Thanks in advance,

Regards, Adam.

-- 
Adam CECILE                    Linbox / Free&ALter Soft
152 rue de Grigy               tél: +33 3 87 50 87 95
Technopôle Metz 2000           fax: +33 3 87 75 19 26
57070 METZ - France            http://www.linbox.com