Test Diagnostic 

mail-dakar:/# cat /proc/mdstat 
Personalities : [raid1] 
md0 : active raid1 sdb1[1]
      732571904 blocks [2/1] [_U]
     
unused devices: <none>

mail-dakar:/# fdisk -l

Disk /dev/sdb: 750.2 GB, 750156374016 bytes
255 heads, 63 sectors/track, 91201 cylinders, total 1465149168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0008f351

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1              63  1465144064   732572001   fd  Linux raid autodetect

Disk /dev/sdd: 750.2 GB, 750156374016 bytes
255 heads, 63 sectors/track, 91201 cylinders, total 1465149168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

   Device Boot      Start         End      Blocks   Id  System
/dev/sdd1              63  1465144064   732572001   fd  Linux raid autodetect

Disk /dev/sda: 16.4 GB, 16372465664 bytes
255 heads, 63 sectors/track, 1990 cylinders, total 31977472 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00086626

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1              63     9767519     4883728+  83  Linux
/dev/sda2         9767520    11727449      979965   83  Linux
/dev/sda3        11727450    21494969     4883760   83  Linux
/dev/sda4        21494970    31969349     5237190    5  Extended
/dev/sda5        21495033    25398764     1951866   82  Linux swap / Solaris
/dev/sda6        25398828    31969349     3285261   83  Linux

Disk /dev/sde: 750.2 GB, 750156374016 bytes
81 heads, 63 sectors/track, 287115 cylinders, total 1465149168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000801ea

   Device Boot      Start         End      Blocks   Id  System
/dev/sde1            2048  1465149167   732573560   83  Linux

Conclusion

Le disque défectueux est donc le disque /dev/sdd1

Résolution du soucis

mail-dakar:/# mdadm --manage /dev/md0 --remove /dev/sdd1

sfdisk -d /dev/sdb | sfdisk /dev/sdd

* Ajout du disque /dev/sdd1 au volume RAId mdo 

mdadm --manage /dev/md0 --add /dev/sdd1

* On suit la progression de la recontruction du RAID