You want to backup to a second partition on your drive?
That's far and away the poorest form of backup there is. It is always
possible that a hard drive crash, user error, nearby lightning strike,
virus attack, even theft of the computer, can cause the loss of
everything on your drive.
If your data is important to you, back up to external media that is
not kept attached to the computer. I recommend buying an external disk
drive.