I think I messed up pretty bad. On my old system, I had 2 identical drive that were assembled with mdadm as a MD RAID 10 with a "far" layout.
When building my new system and migrating the two disks, I had a total brain fart, and instead of doing assemble and scan, I ran the following command:
mdadm --create --verbose /dev/md0 --level=1 --raid-devices=2 /dev/sdd1 /dev/sde1
When /dev/md0 wouldn't mount, I quickly realized that this was not what I intended, but the damage was done, as mdadm had started the sync. I have stopped mdadm (mdadm --stop /dev/md0), and now I can't mount the drives individually (unknown filesystem type 'linux_raid_member'), and parted doesn't see any filesystem on the partitions of the individual drives.
Is there a way to recover the data from either drive, or did mdadm completely destroy both drives in an unrecoverable way?
Creating a raid array resyncs, but does not zero. If the new array happens to be in the same location (likely), and the same type (raid level and superblock type), your data should be readable. Im not aware of the 'far' layout and how it affects your specific case.