If you ever get one of these, count your lucky stars and get the array fixed. In my case I have lost one of the drives.
This is an automatically generated mail message from mdadm
running on debian
A DegradedArray event had been detected on md device /dev/md0.
Faithfully yours, etc.
P.S. The /proc/mdstat file currently contains the following:
Personalities : [linear] [raid1]
md0 : active raid1 hdc1[1]
78148096 blocks [2/1] [_U]
unused devices: