$ sudo mdadm --examine /dev/sde 
/dev/sde:
          Magic : a92b4efc
        Version : 00.90.00
           UUID : 78a2027d:3ac0179e:7981d3ac:48bf4033
  Creation Time : Sat Jul 10 23:19:32 2010
     Raid Level : raid5
  Used Dev Size : 1465138496 (1397.26 GiB 1500.30 GB)
     Array Size : 4395415488 (4191.79 GiB 4500.91 GB)
   Raid Devices : 4
  Total Devices : 4
Preferred Minor : 0

    Update Time : Wed Jul 14 23:34:53 2010
          State : clean
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0
       Checksum : e9bcab8 - correct
         Events : 58

         Layout : left-symmetric
     Chunk Size : 64K

      Number   Major   Minor   RaidDevice State
this     3       8       64        3      active sync   /dev/sde

   0     0       8       16        0      active sync   /dev/sdb
   1     1       8        0        1      active sync   /dev/sda
   2     2       8       48        2      active sync   /dev/sdd
   3     3       8       64        3      active sync   /dev/sde



$ sudo mdadm --assemble --scan /dev/sdb /dev/sdc /dev/sdd /dev/sde
mdadm: /dev/sdb not identified in config file.
mdadm: /dev/sdc not identified in config file.
mdadm: /dev/sdd not identified in config file.
mdadm: /dev/sde not identified in config file.