Bug#815187: Similar problem
On Sat, Feb 04, 2017 at 11:33:02PM +1000, David wrote:
> Hi. I'm a noob but I think I had a similar problem.
> Legacy BIOS on laptop with 2 identical SATA disks.
> Windows 7 on /dev/sda1. Installed jessie 8.7.1 from USB on /dev/sdb2 (swap
> on sdb1)
> Grub wanted to install to /dev/sda MBR but I wanted to keep the windows
> installation native and boot Debian from /dev/sdb using BIOS boot options.
> So I specified /dev/sdb MBR as target for grub.
> Completed without error but then not bootable from /dev/sdb. Once it said
> "Missing operating system" but mostly there was just a blinking cursor
> Fixed by booting from a Live CD, installing grub from there using steps in
> this post
> Installed without errors and now working as desired.
> I'm happy to provide any logs that would help but might need some guidance
> to find the relevant info.
It is quite likely that the bios swaps the device ID of sda and sdb when
you choose to boot sdb, which then means grub would get confused since
it was installed expecting sdb to be the second disk, but when booted
it is suddenly the first disk instead.
I suspect to make it happy would require convincing grub that sdb is in
fact the first hd in the system (In older grub versions one would do
this by changing the device.map file in /boot/grub but I don't recall
if that is still used).
Or you could change the order of the disks in the bios (somehow) before
booting the installer and hopefully sdb would be the first disk then
from grub's point of view.
This is my guess at the problem at least.