Hi,
I definitely suggest you make a backup of each device superblock and distribute it somewhere safe in the unlikely event two devices in a mirrored array stop cooperating. The superblocks do come in handy from time to time when they can't be acquired once problems happen.
Do you have any suggestions on how to do this?
mdadm -E for each device, and point it to a file using >> - for the purposes of the backup you could write all devices to one file, it's up to you.
Ah, I thought you were referring to actually storing information from the disk itself, such as the bootsector or MBR, not just a list of the partition info.
There's also a great resource on recovering a failed array here:
https://raid.wiki.kernel.org/index.php/RAID_Recovery
Thanks, Alex