Trying again: I installed grub twice on two drives, how to fix it?

[Ralf Mardorf]

On Sun, 3 May 2020 09:01:57 +0200, M. Fioretti wrote:
>I had Ubuntu 19.10 on my laptop hd, added an SSD drive to it,
>installed Ubuntu 19.10 on that SSD too. But I did some mistake, so now
>I have 2 working ubuntu installs on both disks, and a grub that lists
>them both, but by default points to the one on the HD. I want to have
>Ubuntu and grub only on SSD, so I can repartition the whole HD drive
>as /home.
>       
>On Tue, Feb 25, 2020 09:26:53 AM +0100, Marco Fioretti wrote:
>> In practice, now when I boot I get a grub menu giving me 3 choices
>> (besides memtest, and safe/recovery options), in this order, all
>> working:
>> 
>> * Ubuntu 19.10 on /dev/sda (old hard drive)
>> * windows
>> * Ubuntu 19.10 on /dev/sdb (new SSD drive)

Hi,

I suspect you are misinterpreting something. Likely the GRUB packages
are installed on both installs and likely both installs contain GRUB
configuration files, but unlikely GRUB itself is installed on both
drives.

At first you could run

diff /boot/grub/grub.cfg /mount/point/install_2/boot/grub/grub.cfg

to take a look what grub.cfg files were generated, since this allows to
do some conclusions. The path to GRUB configs might be incorrect, I'm
using syslinux (not GRUB) and the mount point definitively needs
editing.

While one GRUB probably could chainload another GRUB, it doesn't matter
at all, if one or two GRUBs are installed. The automatic generated GRUB
menu will show both installs and those are for sure not chainloaded. To
ensure that GRUB from the SSD and not GRUB from the HDD is used, you
need to change the boot order by the BIOS settings. Either ensure that
the SSD is listed before the HDD or disable the HDD in the boot list
completely. However, once the wanted GRUB is selected, the menu likely
still shows both installs. If GRUB should be installed on both
drives, but I don't think so, the first step is to ensure that
the SDD is a boot device, that is listed before the HDD, in the boot
devices list of the BIOS settings. If you have done this, we could
continue with the next step.

For the first step restart your computer and before the GRUB menu
appears, push the Delete-key. This key is usually one of those, to get
into the BIOS settings dialog. Search for boot options, than change
them and exit _with saving_ the changes.

If GRUB should not be installed on both drives, that is my guess, no
GRUB menu will appear. If so undo the changes to the BIOS settings
manually.

You likely need to install GRUB to the SSD, since it's likely just
installed to the HDD.

However, you could try what I explained first.

Regards,
Ralf