Peter T. Breuer wrote:
i do not believe you would have any advantage in stacking md above lvm
anyway.
    

That is right. In fact it sounds downright risky to me.
  

I've actually considered a few times how one might be able to merge the md functionality into LVM2 (device-mapper) for having software-RAID part of the logical volume system (since a software-RAID partition is a logical volume of another type anyway).

It would require some significant effort, but it seems doable.
--
Michael T. Babcock
http://mikebabcock.ca