convert /dev/md0 to /dev/sda1

view story

http://unix.stackexchange.com – I used a Software-RAID I and want to access the data without RAID now. After mdadm --fail /dev/md0 /dev/sda1 mdadm --remove /dev/md0 /dev/sda1 I tried mount -t ext4 /dev/sda1 /mnt but dmesg says [ 5620.788838] EXT4-fs (sdb1): ext4_check_descriptors: Block bitmap for group 1 not in group (block 0)! [ 5620.788841] EXT4-fs (sdb1): group descriptors corrupted! Isn't it possible to convert a RAID-partition to non-RAID? Do I have to copy all files to another partition, delete the RAID partition and create a new file system? (HowTos)