If you have a degraded or missing raid array, please post the following info (in code boxes) with your question.
Login as root locally or via ssh - Windows users can use putty:
- cat /proc/mdstat
- blkid
- fdisk -l | grep "Disk "
- cat /etc/mdadm/mdadm.conf
- mdadm --detail --scan --verbose
- Post type of drives and quantity being used as well.
- Post what happened for the array to stop working? Reboot? Power loss?