One dangeours trap when RAID1 is used is to NOT use labels in /etc/fstab like RedHat/Fedora likes to do. This actually happened:
/dev/md0 is made out of /dev/sda1 and /dev/sdb1 and is the root drive. /dev/md1 is made out of /dev/sda3 and /dev/sdb3, formatted with ext3 and with the label "data".
After the initial resync upon next reboot Linux will see three drives called "data", /dev/sda3, /dev/sdb3 and the actual raid device /dev/md1.
The Linux machine did mount /dev/sdb3 as data instead of /dev/md1 until /etc/fstab was corrected.