bash-4.2# mdadm --detail /dev/md0
/dev/md0:
        Version : 1.2
  Creation Time : Sat Feb 12 08:52:08 2011
     Raid Level : raid1
     Array Size : 39397364 (37.57 GiB 40.34 GB)
  Used Dev Size : 39397364 (37.57 GiB 40.34 GB)
   Raid Devices : 2
  Total Devices : 2
    Persistence : Superblock is persistent

    Update Time : Thu Mar 15 01:46:10 2012
          State : clean 
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           Name : firefox:0
           UUID : 794e89dc:b560780c:30411299:2f3a8ac1
         Events : 128503

    Number   Major   Minor   RaidDevice State
       2       8       17        0      active sync   /dev/sdb1
       3       8        1        1      active sync   /dev/sda1
bash-4.2# mdadm --detail --scan
Segmentation fault (core dumped)