The easiest method might be to boot from installation media, run the "rescue" install, chroot to the disk you want to use, then run update-grub from there
All the very best, as ever, Andy C. On Sun, Aug 30, 2020 at 2:44 PM David <bouncingc...@gmail.com> wrote: > On Sun, 30 Aug 2020 at 20:03, Rick Thomas <rick.tho...@pobox.com> wrote: > > > So what am I missing? How do I tell grub on the new disk to use the > root partition and volume-group on the new disk? > > Hi, I have written this message from memory > without testing any of the commands, and > I don't actually use any of these commands myself > so I hope it doesn't contain any errors. > > You wrote that you copied /boot. This means that you > copied the grub configuration file (/boot/grub/grub.cfg) > unchanged, so the new grub is configured to boot > the old system. > > Even though you reinstalled the bootloader on the > new drive, you kept the old config file telling it to > to boot the old drive. > > One answer might be to run 'update-grub' but I can't > give you exact instructions because I don't like that > aspect of grub so I prefer to write my own grub.cfg > files without all the bloat. > > I expect doing that would use os-prober to generate > a new grub.cfg file with a menu that offers to boot > any of all the operating systems that os-prober finds. > I think that's the usual default method. > > I think you could backup /boot/grub/grub.cfg and just try it > and see what happens. If you backup to for example > /boot/grub/grub.cfg-BACKUP then if something goes wrong > you can just enter > 'configfile grub.cfg-BACKUP' at the grub> prompt to use > the old version. > >
