The first block of an ext4 filesystem is called the superblock - it contains essential metadata. There are backup copies of the superblock scattered throughout the filesystem; they can be used to recover if original superblock gets corrupted. They can be located with
dumpe2fs and repairs can be attempted with
e2fsck. I've found a lot of info on the normal recovery process itself so this question isn't about that.
What if all the superblock backups get corrupted? Does it make sense to manually create a backup superblock and to store it on a separate drive? How do you go about making such a copy? Or does it not make any sense because in the event of all backups being corrupt the filesystem is so far gone there is no point in trying to repair the superblock?