I encountered something like this, when installing Stretch (when it was current) onto a USB Stick on a Dell laptop. I was installing to the USB Stick to leave alone the Windows 7 Home installation in the Hard Drive. It didn't come with a DVD Drive, so I used an external USB DVD Drive for the Install.
So, during Install, the Hard Drive was /dev/sda, the DVD Drive was /dev/sdb and the USB Disk with Stretch was /dev/sdc.
On the Reboot, I, of course removed the USB cable for the DVD Drive and got dumped into the Grub Rescue mode, where it was looking for Stretch on /dev/sdc but it was now on /dev/sdb!
My final solution was to backup, and then blow away Windows 7 and Install Buster on the Hard Drive. (Yes, it took long enough for Buster to become the Stable Build).
The Geek Diary wasn't available to me when I encountered this issue. Thanks for the link!
Kenneth Parker
On 2020-11-16 1:48 p.m., Martin McCormick wrote:
> I have goofed, I think. There is a serca-2000-vintage Dell
> Optiplex that has been working fine up to yesterday when I did
> the usual apt-get update followed by the apt-get upgrade on
> buster. The update and upgrade appeared to work.
>
> One of the things that got visited was grub and it was
> then that I was reminded that there was another drive in the
> system that had a bootable image of buster on it also. Grub
> reported seeing it on /dev/sdc which is coorrect.
>
> This particular system has a zip drive that always shows
> up as /dev/sdb so the next hard drive after /dev/sda is /dev/sdc.
>
> I rebooted to make sure all was well and waited and
> waited . . .
>
> The system sits there like a bump on a log.
>
> I have a usb device that lets one mount IDE and SATA
> drives that are outside the system so I pulled the sata drive
> which is the boot drive for the now dead system and plugged it in
> to the usb converter.
>
> the drive breezes through fsck and looks perfectly
> normal.
>
> I looked at /boot/grub/grub.cfg which one is not supposed
> to edit as grub builds it based on /etc/default/grub which one
> does edit.
>
> If I was to mount that partition on a working system, it,
> of course, will have a different device number such as /dev/sde1
> instead of /dev/sda1 which it should have when booting up the
> system it normally runs in.
>
> Is there a safe way to mount this drive, possibly using
> chroot, re-run grub-config and get the drive bootable again?
>
> If I look at grub.cfg and /etc/default/grub, everything
> looks as if it should work but it doesn't.
>
> I think boot problems are some of the most agrevating
> issues. They are true show stoppers.
>
> I've got backups but that's beside the point. Unless I
> can fix whatever happened, it's going to be quite a time waster.
>
> Thanks for any constructive suggestions.
>
> Martin McCormick
>
--
Regards,
John Boxall