Nuub question ... bare metal install to second drive .. need Ubuntu grub entry to boot second drive

[Gerald Talton]

I want to start experimenting with CoreOS. I did a bare metal install on a second drive from Ubuntu just now and that worked just fine.

The problem is this older motherboard doesn't allow selecting which SATA drive to boot from so it always boots the lowest SATA drive first .. meaning the Ubuntu.

However I have grub on Ubuntu and I should be able to have grub .. boot the second drive .. IF I can figure out the proper grub config.

Using grub-customizer and os-prober .. they both see a Linux distro on /dev/sdb3 .. however as I expected I see a "Legacy BIOS Bootable" partition on /dev/sdb1.

When I grub boot to /dev/sdb3 .. it seems CoreOS is in a maintenance/recovery mode .. so .. not what I want.

Should I try to configure grub to boot /dev/sdb1 like my instincts tell me?

Thanks for any help and regards,

Gerald Talton

[Gerald Talton]

currently trying this grub2 bootloader option:

[Michael Marineau]

In order for updates to work our own grub bootloader will need to be
used, so you'll need to configure your primary bootloader to chainload
the CoreOS one on the second disk. If booting in EFI mode that'll be
(hd1,gpt1)/efi/boot/bootx64.efi or in legacy bios use (hd1) or
(hd1,gpt2). You'll need to write your own menuentry by hand and add it
to Ubuntu's /etc/grub.d/40_custom or similar.

If you don't care about working updates you may be able to skip our
grub and boot using the default grub configuration as long as the
kernel is given arguments like "root=/dev/sdb9 mount.usr=/dev/sdb3 rw"