This is a great tutorial for those first dipping into raid on linux. A few comments though....

A short abstract would help. It took me a while to realize that what was going on was this:

Make a new array, copy your existing drive's data to it, make it bootable, boot it, blow away your original drive by making it a part of the new array and let it sync over.

My goal was to make my new drive be the new part of the array and get synced over. I didn't realize that you can't just make a working disk part of an array, you have to start with a new disk and then sync over to it.

The other thing I wanted to add was I had a problem took me a week to figure out.

 I have three disks in the machine, I was only making an array out of one partition.

When the machine was booted normally, grub's perspective of hd0 was sda, hd1 was sdb and hd2 was sdc. Makes sense.

So when I tried to make sda and sdc my array, naturally I made the grub menu.lst say root(hd2,0)

Error 15 file not found.

Then after a week of trying everything I could think of, I finally got the bright idea to boot grub and get to the command line.

After some tab completion experiments I realized that on boot hd1 and hd2 are swapped.

So obviously it couldn't find the kernel or initrd because it was looking at the wrong disk. I set root(hd1,0) and voila. Boot to array.

No idea why it does that, but now I've got it working.

Thanks again for a great tutorial.