How I lost my data trying to back it up

dmraid is capable of parsing the following metadata:

Well, it turns out that the integrated LSI hardware RAID that this server comes with, actually uses the metadata format. You’d never see that when its activated (as the LSI hardware RAID would completely mask the underlying members from the OS), but it’s there and if you ever manage to take a look at the very last sector of each member, you’d see something like this:

, is the superblock magic number. As soon as dmraid got activated (which it does so automatically in Ubuntu Desktop version), it started rebuilding members of the RAID array to make what it was thought was an inconsistent RAID 10, consistent again.

Source: hamy.io