create raid1 on a installed system

[Rashkae]

Asif Iqbal wrote:

> 
> http://tldp.org/HOWTO/Software-RAID-HOWTO-7.html#ss7.6
> 

I did not mean for you to follow any step by step from the howto.
honestly, I think there is no such guide for what you are trying to do,
but rather, it's only possible to gather understanding of how the system
works and how you can manipulate it to your ends.

Reading the how to should give you a firm grasp on the use of mdadm and
partitioning for Raid.

Once you understand those concepts, the original idea is still the path
you need to follow.

Install new drive, partition new drive, create degraded raid array on
new drive, clone existing installation to new drive, boot into new drive
to test.  (chances are, the first time you do this, you will overlook
something and need a boot/rescue cd anyhow).

Repartition your old drive, add the old drive to your raid array, and
bob's your uncle.