[gentoo-user] Migrating RAID: Degraded RAID5 from RAID1?

[Dan Cowsill]

Hello list,

Currently I have two terabyte hard disks in a RAID1 configuration
using software RAID.  What I'd like to do is add a third disk and
arrive at the end with a RAID5 array.  The problem is I have limited
disk space and not enough room to back up all of the data on the array
in its current form.  What I'd like to know is if it is possible to
use two disks to make a degraded RAID5 array, move the data onto it
from one of the mirror disks, and then add the mirrored disk into the
new array?

Thanks,
D