Topic: RAID fails but Disks were OK

[rshiras]

Sorry for the newbie question, I know this must be posted elsewhere but I can't find it.
SME Server release 7.5.1
I keep getting RAID errors that say my software array has a bad drive.  This has happened twice recently, a few weeks apart. 
ALARM! RAID configuration problem

Current configuration is:

Personalities : [raid1]
md2 : active raid1 hdc2[1]
      195253888 blocks [2/1] [_U]
     
md1 : active raid1 hdc1[1]
      104320 blocks [2/1] [_U]
     
unused devices: <none>

Last known good configuration was:

Personalities : [raid1]
md2 : active raid1 hda2[0] hdc2[1]
      195253888 blocks [2/2] [UU]
     
md1 : active raid1 hda1[0] hdc1[1]
      104320 blocks [2/2] [UU]
     
unused devices: <none>

I replace the "bad drive" as per the how-to and other forum poses like Raid:Manual_Rebuild.
The drives turn out to be OK when tested.  I can delete the partitions and make them into a clean, working drive again.
What can I do to try to pinpoint the actual cause?

[CharlieBrady]

You need to review your /var/log/messages.* logs to determine when and why the partitions were ejected from the RAID mirrors. The notification emails you would have been sent will give you some clue as to the timing.