winterpark:~ # mdadm --detail /dev/md0
/dev/md0:
        Version : 00.90.03
  Creation Time : Fri Sep  8 13:38:57 2006
     Raid Level : raid5
     Array Size : 586050816 (558.90 GiB 600.12 GB)
    Device Size : 293025408 (279.45 GiB 300.06 GB)
   Raid Devices : 3
  Total Devices : 4
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Sat Dec 16 13:05:44 2006
          State : clean
 Active Devices : 3
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 1

         Layout : left-symmetric
     Chunk Size : 128K

           UUID : 2e83bb15:f1e37d9c:a17987d4:108d4a18
         Events : 0.2118065

    Number   Major   Minor   RaidDevice State
       0      22        1        0      active sync   /dev/hdc1
       1      22       65        1      active sync   /dev/hdd1
       2       8        1        2      active sync   /dev/sda1

       3       8       17        -      spare   /dev/sdb1