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

Tue Feb 12 00:01:08 UTC 2019
Fred Smith <fredex at fcshome.stoneham.ma.us>

On Mon, Feb 11, 2019 at 04:16:38PM +0100, Simon Matter via CentOS wrote:
> > 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!
> 
> To me the easiest method seems to:
> 
> - boot into rescue mode, not mounting any disks
> - directly dd all complete disks to files on a USB disk or to a remote host
> - reboot and update as usual
> 
> If anything fails you can again boot into rescue mode (maybe with the help
> of USB/DVD/CD) and:
> 
> - recover all disks using dd from the backups made before
> - reboot and be back on 7.5
> 
> Any reason why this shouldn't work?

Thanks for the reply!

by rescue mode, do you mean (1) the "rescue" kernel in the boot menu?
Or (2) an option on one of the installer DVDs?

Wouldn't (1) boot from the existing drives and mount them?

Fred
-- 
---- Fred Smith -- fredex at fcshome.stoneham.ma.us -----------------------------
                      The eyes of the Lord are everywhere, 
                    keeping watch on the wicked and the good.
----------------------------- Proverbs 15:3 (niv) -----------------------------