[root@ntinstall /]# mdadm --detail /dev/md0
/dev/md0:
        Version : 0.90
  Creation Time : Mon Nov 22 10:05:42 2010
     Raid Level : raid1
     Array Size : 976759936 (931.51 GiB 1000.20 GB)
  Used Dev Size : 976759936 (931.51 GiB 1000.20 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Tue Jul  5 14:52:39 2011
          State : clean, degraded
 Active Devices : 1
Working Devices : 1
 Failed Devices : 1
  Spare Devices : 0

           UUID : 4a7754f3:dd3d84f1:76d79ba5:0b0439b5
         Events : 0.6652

    Number   Major   Minor   RaidDevice State
       0       8        1        0      active sync   /dev/sda1
       1       0        0        1      removed

       2       8       17        -      faulty spare   /dev/sdb1
[root@ntinstall /]#