It's really the integrity checking. As you say, mdadm is much more suited if you need to change the geometry of you array, add disks and so on. It's much handie

It's really the integrity checking. As you say, mdadm is much more suited if you need to change the geometry of you array, add disks and so on. It's much handier for the smaller business, who can't afford a second send of disks to build a second array on when they want to reshape. We ran btrfs on top of mdadm, getting both integrity checking and flexibility (although this just tells you that something is wrong).