mdadm kicking non-fresh disk from array, Physical disk is "removed" from mdadm raid array after a reboot

Issue

• After a reboot, the /dev/hda2 disk was gone from the mdadm array /dev/md2

  # mdadm --detail /dev/md2
  /dev/md2:
          Version : 00.90.01
    Creation Time : Sat Sep 16 11:45:26 2006
       Raid Level : raid1
       Array Size : 5172864 (4.93 GiB 5.30 GB)
      Device Size : 5172864 (4.93 GiB 5.30 GB)
     Raid Devices : 2
    Total Devices : 1
  Preferred Minor : 2
      Persistence : Superblock is persistent
  
      Update Time : Thu Dec 16 05:57:21 2010
            State : clean, degraded
   Active Devices : 1
  Working Devices : 1
   Failed Devices : 0
    Spare Devices : 0
  
             UUID : 2693ade7:d6ab52a5:52bd9e0c:9ce447e7
           Events : 0.39983614
  
      Number   Major   Minor   RaidDevice State
         0       0        0        -      removed
         1      22        2        1      active sync   /dev/hdc2
  

• The logs contained the following

  # egrep -i 'md2|hda2' /var/log/message*
  /var/log/messages:Dec 12 11:33:10 <hostname> kernel:  hda: hda1 hda2 hda3 hda4 < hda5 hda6 hda7 >
  /var/log/messages:Dec 12 11:33:10 <hostname> kernel: md: hda2 has different UUID to hdc7
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md: hda2 has different UUID to hdc6
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md: hda2 has different UUID to hdc5
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md: hda2 has different UUID to hdc3
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md:  adding hda2 ...
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md: created md2
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md: bind<hda2>
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md: running: <hdc2><hda2>
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md: kicking non-fresh hda2 from array!
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md: unbind<hda2>
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md: export_rdev(hda2)
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: raid1: raid set md2 active with 1 out of 2 mirrors
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md: considering hda2 ...
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md:  adding hda2 ...
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md: md2 already running, cannot run hda2
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md: export_rdev(hda2)
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md: considering hda2 ...
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md:  adding hda2 ...
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md: md2 already running, cannot run hda2
  /var/log/messages:Dec 12 11:33:11 <hostname> kernel: md: export_rdev(hda2)
  /var/log/messages:Dec 12 11:33:12 <hostname> kernel: md: considering hda2 ...
  /var/log/messages:Dec 12 11:33:12 <hostname> kernel: md:  adding hda2 ...
  /var/log/messages:Dec 12 11:33:12 <hostname> kernel: md: md2 already running, cannot run hda2
  /var/log/messages:Dec 12 11:33:12 <hostname> kernel: md: export_rdev(hda2)
  /var/log/messages:Dec 12 11:33:12 <hostname> kernel: md: considering hda2 ...
  /var/log/messages:Dec 12 11:33:12 <hostname> kernel: md:  adding hda2 ...
  /var/log/messages:Dec 12 11:33:12 <hostname> kernel: md: md2 already running, cannot run hda2
  /var/log/messages:Dec 12 11:33:12 <hostname> kernel: md: export_rdev(hda2)
  /var/log/messages:Dec 12 11:33:12 <hostname> kernel: md: considering hda2 ...
  /var/log/messages:Dec 12 11:32:26 <hostname> fsck: /dev/md2: clean, 2222/647680 files, 290857/1293216 blocks
  /var/log/messages:Dec 12 11:33:12 <hostname> kernel: md:  adding hda2 ...
  /var/log/messages:Dec 12 11:33:12 <hostname> kernel: md: md2 already running, cannot run hda2
  /var/log/messages:Dec 12 11:33:12 <hostname> kernel: md: export_rdev(hda2)
  /var/log/messages:Dec 12 11:33:13 <hostname> kernel: md: considering hda2 ...
  /var/log/messages:Dec 12 11:33:13 <hostname> kernel: md:  adding hda2 ...
  /var/log/messages:Dec 12 11:33:13 <hostname> kernel: md: md2 already running, cannot run hda2
  /var/log/messages:Dec 12 11:33:13 <hostname> kernel: md: export_rdev(hda2)
  /var/log/messages:Dec 12 11:33:13 <hostname> kernel: EXT3 FS on md2, internal journal