I have three disks which used to hold an MD RAID5 array. I have since removed (or so I thought) this array and created partions for btrfs and swap space. On rebooting the machine, MD still binds the devices that used to hold the old array, causing the new filesystem to fail to mount.
It was suggested to me that the old superblocks of the raid arrays might be left behind causing MD to think it is a real array and thus binding the disks. The suggested solution was to use mdadm --zero-superblock to clear the superblock on the affected disks. However, I don't really know what this does with the disk. Since this disk holds partitions I don't really want to start zeroing parts of it blindly.
So what procedure should I follow to safely clear the MD superblocks without damaging the other partitions and file systems on the drives?
This question essentially asks the same thing, but there isn't a clear answer as to whether doing mdadm --zero-superblock on a repartitioned device is actually supposed to be safe: mdadm superblock hiding/shadowing partition
