Re: Do I need to act on this warning from apt when installing grub?

[Goh Lip]

On 12/14/22 17:15, Chris Green wrote:
> On Wed, Dec 14, 2022 at 10:31:40AM +0800, Goh Lip wrote:
> > On 13/12/2022 18:55, Chris Green wrote:

> > Is your partition table GPT, not msdos?
> Yes, it's GPT:-
>
>      Disk /dev/sda: 931.51 GiB, 1000204886016 bytes, 1953525168 sectors

>      Disklabel type: gpt

>      Device       Start        End    Sectors  Size Type
>      /dev/sda1     2048       4095       2048    1M BIOS boot
>      /dev/sda2     4096    1054719    1050624  513M EFI System
>      /dev/sda3  1054720 1953523711 1952468992  931G Linux filesystem
>
>
> (There's an 8Tb USB drive as well, this is my backup system which
> lives in the garage, quite a way away from the house)


See 
https://www.gnu.org/software/grub/manual/grub/grub.html#BIOS-installation

To set up bios-legacy boot on gpt partitioning properly, you will need a 
small partition labelled "bios_grub".
And yes, without it, as you found out, it will still install and boot. 
But it will not be reliable and will, in time, likely to fail again. And 
you can still make it work again the way you have done (and will likely 
fail again).

Personally, I would suggest that for gpt partitioning, boot in uefi. And 
in msdos partitioning, boot in bios-legacy (though that too can be 
booted in uefi boot - with unreliable performance).

Hope this explains. Regards.

ps: best when issuing grub-install command, use "--target=i386-pc" in 
that command for boot-legacy boots and "--target=x86_64-efi" for uefi 
boots, especially when installing legacy in gpt or uefi in msdos (latter 
always not recommended, but I've done it)