Dual-boot with 1 drive for each installation

[Thanks for the Fish]

Hey

as the title says. I'm interested in adding one drive from one pc with a Mint system on it into another machine with an existing Windows installation but all the guidelines about dual-boot that I found so far assume a fresh installation of one (or both) systems and a configuration of the boot loader (usually Grub).

Both devices use BIOS. I plan to use windows very rarely for some specific tasks and was wondering if I can't just put the drive in and sort of "select" the os by swapping the boot order of the drives in the BIOS?

any help is much appreciated!

cheers

[rene]

Sure, assuming you said BIOS as in BIOS-not-UEFI everything should Just Work --- but I'd simply use Grub rather than BIOS boot-order switching.

That is; assuming the existing Windows drive to in Linux terrms be sda and the to be newly installed Linux drive sdb you boot into sdb once via the BIOS boot-select menu (F11, F12, ...) and then install Grub also in the MBR of sda: sudo grub-install /dev/sda. At also sudo update-grub it should find both Windows and your Linux install and should when rebooting from sda again present you the choice.

If you don't normally want to see the Grub menu at boot that's easy to adjust later as well; you'd then need to hold down Left-Shift while booting to get the choice.

[AndyMH]

Assuming legacy boot, both win and drive you are going to fit, just fit the drive, should work. You will need to change the BIOS boot order so that the mint drive is top of the list. If you want grub to give you a menu on boot so you can choose mint or win, in a terminal sudo update-grub. Next time you boot you should see the grub menu.

Assuming drives as suggested by rene, sda=win, sdb=mint, if you install grub to sda you will no longer be able to boot win directly, the windows bootloader will be overwritten.

[rene]

Assuming drives as suggested by rene, sda=win, sdb=mint, if you install grub to sda you will no longer be able to boot win directly, the windows bootloader will be overwritten.

I feel "not being able to boot win directly" seems a little alarmingly put; you'd boot Windows though Grub in the very same way as a on a single-drive dual-boot setup, and that's also most of the point I (more or less) had; having an as-standard-possible setup.

Admittedly keeping the Windows MBR on sda untouched and booting from sdb in the BIOS is in fact also fine --- and if that Windows install is a current Windows 10 one would guard against a major Windows update overwriting Grub. So; whatever you care for...

[AndyMH]

But correct, the advantage of a dual boot setup with each OS on its own drive is that they are independent of each other. Putting the bootloader on one drive and the OS on the other negates this. It also leaves you open to the vagaries of MS with a win update borking grub, or more likely, one drive dies and you find you can't boot although the other drive is perfectly okay. You can put grub on the win drive, I just wouldn't recommend it.

[Thanks for the Fish]

Addendum:

Instead of having to change the boot order, I simply excluded the drive with windows on it from the boot order list in the BIOS. Unfortunately, Mint doesn't load at all - I don't even make it to the grub menu. What did I miss?

Assuming drives as suggested by rene, sda=win, sdb=mint,

And how do I change the disk id's (from sda to sdb?

boot info log here: https://paste2.org/6X9JPgDc

[AndyMH]

Instead of having to change the boot order, I simply excluded the drive with windows on it from the boot order list in the BIOS

Which is probably the cause of your problem, grub got installed to your win drive.

And how do I change the disk id's (from sda to sdb?

You can't, unless you physically swap the drives over, the drive id's are assigned by linux in the order that the system reports them.

[Thanks for the Fish]

grub got installed to your win drive.

I don't think it did?

============================== Boot Info Summary ===============================

=> Grub2 (v2.00) is installed in the MBR of /dev/sda and looks at sector 1 of
the same hard drive for core.img. core.img is at this location and looks
for (,msdos1)/boot/grub. It also embeds following components:

modules
---------------------------------------------------------------------------
fshelp ext2 part_msdos biosdisk
---------------------------------------------------------------------------
=> Windows Vista is installed in the MBR of /dev/sdb.
.
.

sdb1: __________________________________________________________________________

File system: ntfs
Boot sector type: Windows Vista: NTFS
Boot sector info: No errors found in the Boot Parameter Block.
Operating System: Windows 8 or 10
Boot files: /bootmgr /Boot/BCD /Windows/System32/winload.exe

cheers