Gary Dale grabbed a keyboard and wrote:
You'd only need one new drive, and that's just because your two current
drives are apparently of different sizes. However, you can also create a
RAID 1 array using the smaller drive and part of the larger one. The
rest of the larger drive wouldn't be mirrored but could be used for data
that doesn't need backing up (e.g. the root partition, with just /home
being mirrored).
My particular issue is that while I have a second drive for backups
already installed in the Windows machine, I don't for the Linux machine.
So when I'm ready to start this, I'm going to have to buy the drive.
Thus, needing to scrape up the money for the second drive to do the
backups to. Buying one and setting it up as part of a RAID instead
protects me from driving a nail through my first drive, but doesn't do
much to actually allow me to have a running backup going, which is kinda
the point of what I'm trying to do at this time. :-)