I think it would be smart first install on one drive and then migrate to a RAID1 set ...
But I do not recommend to use the FakeRaid
The hardware Raid controller (Fakeraid SATA or IDE) built on motherbard are a poor version of software RAID LVM, IMHO
The performances are almost always low and not comparable to those of a "real" dedicated RAID hardware controller (SCSI or SAS).
And last usually needed (but not really true) only when Redmond
OSes shared over the Raid Volume.
So if you use only Linux OS
, I advise you to disable the raid from bios and use software RAID with kernel device mapper...
I think the Raid software for Redmond OSes
is only supported on Windows Server
family (but not shure).
First create two raid partitions (one for each HDD) and then enable the RAID set in mode 1.
mdadm --create /dev/md0 --level=mirror --raid-devices=2 /dev/sda1 /dev/sdb1http://en.wikipedia.org/wiki/Mdadm