Booting Two OSes From Two Different HDDs with GRUB

KartRacer63 · 06-09-2015, 12:02 AM

I'm sorry if this has been asked before, I've searched high and low for a helpful answer to this and everything I've tried so far has not worked. Also, my knowledge of GRUB workings is very, very limited.

I've installed Linux Mint 17.1 Cinnamon (64-bit) alongside Windows 7 Ultimate (64-bit) on separate hard disks (both 1TB in size). Windows is on the sda drive and Mint (and GRUB) is on sdb. Both OSes work fine, but my problem is with the boot. In order to boot into Windows, I have to open the BIOS and tell the computer to check the Windows HDD first, as the Linux disk is set first in the boot order to allow GRUB to appear. This isn't all that big of an issue, but I'd like to be able to launch both systems from GRUB. I've read from multiple threads that it's possible to use GRUB to boot from different HDDs, but I haven't seen any instructions on how to do it, and trying to figure it out for myself has proved unsuccessful.

The main thing I need to know is a way to add Windows to the GRUB menu, so that selecting it will initiate it's boot loader. The Linux Mint installation boots fine from GRUB, which is why I was hesitant to post this here. If the thread isn't appropriate here, please let me know so I can post it in another forum.

Here's a link to boot info generated by Boot Repair:
http://paste2.org/fVLW9e1H

Thank you!

yancek · 06-09-2015, 11:44 AM

You have your windows 7 installed in MBR mode while you installed Mint in UEFI. If you had installed Mint in UEFI I doubt you would have the problem. You have windows code in the MBR of the first (windows) disk and you have the separate EFI partition on the second drive with Mint. The suggested repair of the boot repair output would be to install Grub to the MBR of both disks. Not sure you would want to do that as it will overwrite the windows code in the MBR of its disk. Ordinarily, it would be a simple command to add windows to the Grub boot menu. The problem is with one system (Mint) using UEFI and the other (windows) using MBR. There may be a way around this but I doubt that it will be a simple fix. I don't use UEFI myself so have no suggestions.

KartRacer63 · 06-09-2015, 01:02 PM

Quote:

Originally Posted by yancek

You have your windows 7 installed in MBR mode while you installed Mint in UEFI. If you had installed Mint in UEFI I doubt you would have the problem. You have windows code in the MBR of the first (windows) disk and you have the separate EFI partition on the second drive with Mint. The suggested repair of the boot repair output would be to install Grub to the MBR of both disks. Not sure you would want to do that as it will overwrite the windows code in the MBR of its disk. Ordinarily, it would be a simple command to add windows to the Grub boot menu. The problem is with one system (Mint) using UEFI and the other (windows) using MBR. There may be a way around this but I doubt that it will be a simple fix. I don't use UEFI myself so have no suggestions.

I noticed that as well, and I don't understand how it happened. Before installing either system, I turned off UEFI in the BIOS. I installed Windows first, which installed as MBR. Then Mint, which installed as UEFI, despite UEFI being off. I don't want to use UEFI either, all my dealings with it have been nothing but frustrating.

If Mint could be changed to boot with MBR instead, that seems it may solve the problem, but I'm unsure how to do that.

But thanks anyways.

yancek · 06-09-2015, 04:32 PM

Since Mint is Ubuntu based, you might find an answer at the Ubuntu forums. The link below explains changing EFI to MBR on Ubuntu which should work on Mint. Make sure you read through it before beginning. Haven't used it myself so?? You might try an online search using gdisk as an option.

http://askubuntu.com/questions/36054...i-to-bios-boot