On Fri, May 21, 2021 at 08:52:18AM +0200, Pascal Hambourg wrote: > Le 19/05/2021 à 14:02, Chris Green a écrit : > > > > I've realised the easiest thing to do will be to simply duplicate my > > existing xubuntu 20.10 installation on another partition. As before > > partitions are:- > > > > /dev/nvme0n1p2 ext4 48174 15782 29877 35% / > > /dev/nvme0n1p3 ext4 896193 295877 554724 35% /home > > /dev/sdb1 ext4 10016 183 9306 2% /boot > > /dev/sdb2 ext4 109596 33138 70850 32% /scratch > > /dev/sda1 ext4 938772 222397 668666 25% /bak > > /dev/sdc1 ext4 937872 77 890087 1% /mnt > > > > If I simply copy / to /mnt and also copy /boot to / how do I get grub > > to add the new partition to the boot menu? (/dev/sdc is a SATA disk > > so is visible to the BIOS so /boot can be on there with the OS) > > > > Then if, when I ugrade my 'main' xubuntu 20.10 to 21.04, it falls in a > > heap I can simply boot the xubuntu 20.10 on /dev/sdc1 and everything > > will still work as before (if a little more slowly). > > Duplicate an installed system requires a few more steps because the copy > uses different partitions. You need to adjust /etc/fstab and > /boot/grub/grub.cfg with the new / UUID and no separate /boot. > I need a bit of clarification please.
So I've copied files as I said, with /dev/sdc1 being a copy of /dev/nvme0n1p2 plus a /boot directory containing what's in /dev/sdb1. Yes, I understand I then need to change the /etc/fstab in the /dev/sdc1 filesystem to point to the right places, I can do that OK. How should I do the changes to /boot/grub/grub.cfg? Do I edit /etc/default/grub and then run grub-mkconfig? However I don't really see how this would work, I can set the output file for grub-mkconfig but how do I tell it to use the /etc/default/grub in /dev/sdc1? At what stage does the copy in /dev/sdc1 get added to my boot menu? > I would also install GRUB on /dev/sdc from the copy to be able to boot if > the original installation is so broken that even GRUB does not work any > more. > Definitely, is that just a matter of booting the copy OS and running grub-install? -- Chris Green
