--zero-superblock option will overwrite the superblock with zeros. As I understand, superblock is a 256 byte block on HDD/SSD describing the RAID level used, name of the array, creation time of the array, modification time of the superblock itself etc.
However, how does the
mdadm know where is the superblock located on the disk? Hasn't this changed throughout the versions of superblocks? In addition, is there only a single superblock in use or are there multiple ones for redundancy reasons?