RAID1, Disk Mirroring: Not failing the last device correctly

Issue

• In RAID 1 configuration, when both the disks are failed, state of only one of them is shown as faulty in the output of mdadm --detail /dev/mdX command, and the state of last failed disk is still displayed as active-sync.

  $ mdadm --fail /dev/md0 /dev/sdf
  mdadm: set /dev/sdf faulty in /dev/md0
  
  $ mdadm --detail /dev/md0
  /dev/md0:
          Version : 00.90.03
    Creation Time : Mon Aug 22 22:36:06 2011
      Raid Level : raid1
      ...
     Number  Major  Minor  RaidDevice State
          0      0       0        0      removed
          1      8      80        1      active sync  /dev/sdf  <-- Still the device status is shown as Active Sync
          2      8     112        -      faulty spare  /dev/sdh <-- Device /dev/sdh is already Faulty