How to resize RAID-1 partitions (mdraid)

[Bruno Wolff III]

On Sat, May 29, 2010 at 10:31:11 -0400,
  Sam Varshavchik <mrsam at courier-mta.com> wrote:
> 
> I want to juggle these partitions around. It's not clear to me if
> parted will handle RAID partitions. I think I should resize each
> partition on each drive identically, and parted should end up
> producing identical contents if it's asked to resize two identical
> partitions to the same size, right? But what about the mdraid
> metadata on each partition? Where does mdraid keep it, at the
> beginning or at the end of each partition? If I resize the partition
> with parted, is it going to blow away my raid metadata?

Recent versions of mdraid can keep it either at the front or the back.
Previously the data was stored in the back. Storing it in the back is needed
if you boot off of the device, since grub doesn't support raid and you want
it to think they are ext file systems.