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Re: BIOS Can Not Find Disk




Le 03/12/2017 à 00:09, Felix Miata a écrit :
Michael Lange composed on 2017-12-02 22:33 (UTC+0100):

On Fri, 1 Dec 2017 23:07:15 -0500 Dan Norton wrote:

(...)
What bootloader was installed -- LILO, GRUB, GRUB2, whatever? And,
where?

GRUB2 to sda1.

I did not read this thread in detail, so maybe this has already been
discussed, but I have just now been thinking, shouldn't grub go
to /dev/sda instead of /dev/sda1 ?

Sounds like there is some confusion.
When we talk about the location of GRUB, we actually generally refer to the location of the boot image (1st stage), in a MBR or a PBR. Here sda1 is a "BIOS boot" partition. GRUB cannot install its boot image in a BIOS boot partition. This type of partition is implicitly used by GRUB to install its core image (2nd stage) when installing the boot image in the MBR of a GPT disk.

So I guess that the OP means that the core image of GRUB is in sda1, and the boot image of GRUB is in the MBR of sda.

  OP made it clear his is a multiboot context. Grub on sda works for a first
installation, but guess what happens with the next and subsequent installations
if you allow same with them? Just as traditionally experienced with
re-installation of Windows, each subsequent installation tries to, and typically
does, usurp control from the former, followed by updates to the prior at least
attempting to wrest it back, often with annoying, and time consuming, and
sometimes fatal, consequences. With the complication that is multiboot, some
kind of administrative intervention is inevitably needed.

The option the OP chose is to intervene ab initio. When Grub is installed to an
MBR primary partition, and the MBR contains legacy boot code, and a boot flag is
appropriately set, and the same policy is maintained, a subsequent installation
makes no attempt to usurp control from the first.

That does not match my experience. A subsequent installation does not care about what kind of boot code is in the MBR nor whether a boot flag is set. You just tell the installer where you want to install GRUB and that's all.

EFI and GPT were supposedly created in part to simplify hosting multiple
operating systems,

Not GPT. GPT was just created to handle large disks and large number of partitions without the extended partition kludge.