If this disk partition was on raid1 and you cant mount it, you should:
mdadm --assemble --run /dev/md0 /dev/sdc1
mount /dev/md0 /mnt/data
If this disk partition was on raid1 and you cant mount it, you should:
mdadm --assemble --run /dev/md0 /dev/sdc1
mount /dev/md0 /mnt/data