LinuxQuestions.org - growing raid-6 with mdadm

I currently have a soft raid 6 setup using mdadm and lvm. I'm trying to grow the raid 6, but am having issues. I upgraded to Ubuntu 11.10b, as in hopes of a kernel upgrade, it would fix my issue. However, I'm still unable to expand my raid.

If I cannot expand my raid, I'm open to other suggestions, possibly creating a mirrored raid and then adding it to the raid 6 to appear as 1 drive..? Here are the steps I took

copied the partions from the current to the new

Code:

sfdisk -d /dev/sdc | sfdisk /dev/sda

sfdisk -d /dev/sdc | sfdisk /dev/sdb

added the two drives to the raid

Code:

mdadm --add /dev/md0 /dev/sda1

mdadm --add /dev/md0 /dev/sdb1

set the max size

Code:

mdadm --grow /dev/md0 --size=max

then tried to grow the raid by doing

Code:

mdadm --grow /dev/md0 /dev/sda1

mdadm --grow /dev/md0 /dev/sdb1

on both of those lines, i got this error

Code:

mdadm: can only add devices to linear arrays

I've tried searching around for possible solutions, but have been unlucky in my search.