Re: grub.cfg for RAID devices

[Pascal Hambourg]

Le 20/09/2021 à 13:26, Stéphane Delaunay a écrit :
> on Wednesday, September 15th, 2021 at 12:13 PM, Pascal Hambourg 
> <pascal@plouf.fr.eu.org> wrote:
> > When you are in the system, you just need to install the package
> > grub2-common and run update-grub to generate a proper grub.cfg.
>
> Yes, this was the solution. I think it was a misunderstanding on my part and I 
> got confused about the partitions and installation.
>
> Installing grub without specifying a device parameter added the config to the 
> /boot-RAID and made GRUB on flash open it.

What do you mean by "installing grub without specifying a device 
parameter" ? update-grub does not install GRUB, it only writes grub.cfg.

> I'm not sure whether I should also install grub to sda/sdb as well, because 
> I've read that this can cause issues with grub-update for some reason.

Do you mean "update-grub" ? It writes grub.cfg regardless of whether and 
how an actual GRUB boot loader is installed.

> It's probably not necessary for this system, but might be needed if I need to 
> install the drive in another one.
Indeed installing a GRUB boot loader on the drives is useless if you run 
GRUB as a Coreboot payload. You may install it on both drives if you 
want to boot from a conventional BIOS firmware. Install package grub-pc 
and select both drives when prompted.

Note that this setup won't boot from a UEFI only firmware without legacy 
BIOS compatibility. Achieving redundant UEFI boot is more complicated : 
you need to create non-RAID EFI system partitions on both drives and 
mount them, install package grub-efi-amd64-bin [*] and manually install 
GRUB in both EFI partitions with appropriate commands :

grub-install --target=x86_64-efi --no-nvram --force-extra-removable \
 --efi-directory=/boot/efi1
grub-install --target=x86_64-efi --no-nvram --force-extra-removable \
 --efi-directory=/boot/efi2

[*] Unlike grub-pc, the package grub-efi-amd64 configuration does not 
support multiple locations.