Dual Boot Ubuntu/Windows on two separate hard drives

Question

I have just installed Ubuntu on a hard disk and windows 8.1 on another hard disk. How to make dual boot when pc starts ? As I have mentioned, they are not on different partitions, they are on different hard disks.

Thank you!

Solution

Generally, to make dual-boot work out of the box, one needs to install windows first and then Ubuntu. Ubuntu's bootloader - GRUB2 then autodetects Windows and creates entry in the GRUB bootlist.

If you did the other way round, that is installed Ubuntu and then Windows, then you would need to repair the GRUB to be able to boot into both OSs.

Now coming on to the next part, since you installed the OS on different HDDs altogether, you need to set the HDD with the GRUB bootloader as the first device to boot from in the BIOS.

If you have any issues figuring out the above, you may leave a comment and i will improve the answer.

Comments

[oldfred]

Is this a newer system with UEFI and CSM/BIOS? If so did you install both in the some boot mode. And did you use Something Else and choose to install the grub2 boot loader to the Ubuntu drive? If both are in the same mode run this in Ubuntu: sudo update-grub

[Eduard Luca]

You're a life saver. That comment about setting the right HDD to boot off, did the trick for me. Somehow Ubuntu (or boot-repair) switched the boot HDD to the wrong one, and I didn't know what the heck was going on.