please help converting a running system to mirrored raid array
my current home file server has only 2 SATA ports on its motherboard. one is in use by my boot drive and one is in use by a data storage drive. I also have 2 IDE drives storing data that are only vaguely relevant.
I have ordered 2 new SATA drives that are each individually large enough to hold all of my data with plenty of room to grow. what I intend to try to do is... pull out my boot drive and replace it with one of the new drives, reinstall my OS(Arch Linux) onto the new drive, copy the data from each of my old drives into the new partition structure on the new SATA drive, remove all of the remaining old drives, add the second new SATA drive, then use mdadm to set up a software mirrored raid array.
I have been reading about how to do this for a while now and I learned that I need to change my fstab to point to the new raid devices instead of the old drive, and that I should add a second entry to my menu.lst for the second physical drive so that I can choose to boot to either one in a failure. but nowhere do I see an explanation that I understand of how to actually get the raid array set up and all of the data properly mirrored.
I am asking for a step by step walk through of the process from the moment I boot with both new drives in for the first time to the moment everything is properly mirrored and its time to point fstab and grub at the new raid devices instead of the first of the new drives to be installed. also give me tips if there are other files that need changed to reflect the raid array and not the old drive that I haven't thought of yet.