[CentOS] bare-metal backup before update--options?

Hi all!

I'm a "nervous nellie", I have not yet updated my 7.5 desktop to 7.6
because (1) it has an Nvidia card, and (2) I've heard of problems
upgrading on top of software RAID (using RAID1 with 2 drives).

I need to upgrade it to stay secure, and I want to do a bare-metal backup
first (so I can put it all back as it now is, in case it explodes in my
face), so I'm trying to figure out the safest way to do that. Here are
the choices as I see them, I'd appreciate comments/thoughts:

1. boot from live DVD and manually reassemble the RAID array (how 
would I do that?)
2. degrade the array (with appropriate commands) so that it is running
on just one drive, then boot a live DVD and use dd to back up that drive.
3. Other choices you can suggest?

then after successfully getting a bare-metal backup, reboot it with the
full RAID array and run the update.

Thanks in advance!

Fred
-- 
---- Fred Smith -- fredex at fcshome.stoneham.ma.us -----------------------------
  "And he will be called Wonderful Counselor, Mighty God, Everlasting Father,
  Prince of Peace. Of the increase of his government there will be no end. He 
 will reign on David's throne and over his kingdom, establishing and upholding
      it with justice and righteousness from that time on and forever."
------------------------------- Isaiah 9:7 (niv) ------------------------------