weird bug

        Version : 1.2
  Creation Time : Tue Jun 11 00:09:14 2013
     Raid Level : raid6
     Array Size : 29301350400 (27943.95 GiB 30004.58 GB)
  Used Dev Size : 2930135040 (2794.39 GiB 3000.46 GB)
   Raid Devices : 12
  Total Devices : 12
    Persistence : Superblock is persistent

    Update Time : Tue Oct 21 15:32:08 2014
          State : clean
 Active Devices : 12
Working Devices : 12
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 2048K

           Name : ares:3  (local to host ares)
           UUID : d1ebe146:7d82f264:de242442:1a5a5162
         Events : 137131

    Number   Major   Minor   RaidDevice State
      11       8      176        0      active sync   /dev/sdl
       1       8      160        1      active sync   /dev/sdk
       2       8      128        2      active sync   /dev/sdi
       6       8      144        3      active sync   /dev/sdj
       7       8       16        4      active sync   /dev/sdb
       9       8       48        5      active sync   /dev/sdd
      14       8        0        6      active sync   /dev/sda
      10       8       32        7      active sync   /dev/sdc
      13       8      112        8      active sync   /dev/sdh
      12       8       96        9      active sync   /dev/sdg
      16       8       80       10      active sync   /dev/sdf
      15       8       64       11      active sync   /dev/sde

root@ares:/etc/mdadm# mdadm --detail --scan
mdadm: cannot open /dev/md/3: No such file or directory
root@ares:/etc/mdadm#