mdadm --detail /dev/md/1
/dev/md/1:
        Version : 1.2
  Creation Time : Mon May 13 23:39:33 2013
     Raid Level : raid1
     Array Size : 968324928 (923.47 GiB 991.56 GB)
  Used Dev Size : 968324928 (923.47 GiB 991.56 GB)
   Raid Devices : 2
  Total Devices : 1
    Persistence : Superblock is persistent

    Update Time : Tue May 14 21:32:32 2013
          State : clean, degraded
 Active Devices : 1
Working Devices : 1
 Failed Devices : 0
  Spare Devices : 0

           Name : proxmox:1  (local to host proxmox)
           UUID : 8ba17332:7ae05068:560b8d31:03992133
         Events : 959

    Number   Major   Minor   RaidDevice State
       0       8        5        0      active sync   /dev/sda5
       1       0        0        1      removed