We're pulling a bunch of things (GBs) off of our network storage and archiving it onto external HDDs. Copies are made of each external HDD so that one can go off-site and one can stay here. Is there a way to mirror the two drives (RAID 1?) and copy the data to both at the same time?
I'd suggest you just roll with a simple rsync script for this. Nice thing about not going RAID is then you don't have to worry about the particular RAID implementation you elect actually handles a missing disk... Granted that should work okay anyway..