Tricky questions about multi-boot setup, two HDDs

I rely on Ubuntu, and have Win 7 in the second partition. Curious about other distros, I have looked into Virtualbox and multiple boots. If it can be done without messing with my GRUB, multibooting might be the best option. But my situation has its own difficulties, so I want to ask how I might proceed.

I cloned from sda to sdb because there were bad sectors in sda. Now, sda is last in the BIOS boot order, sdb is third. I also formatted that problematic sda keeping the bad sectors in an unallocated space, and one ntfs partition and a couple of ext4 partitions.

So here are the questions:

  1. If I install another Linux on sda2, then boot into sdb1 (Ubuntu), can I expect my original GRUB to be safe? Can I then add the new Linux (sda2) to GRUB using GRUB Customizer?

  2. If I install Windows 10 on sda1, will it seek and destroy the GRUB on sdb? As long as sda is last in boot order, can I install Win 10 without losing anything from my sdb setup?

  3. THe overall principle guiding me is this: if I install on a different hard drive, and then place it last in boot order, is my main bootable drive (sdb) going to be safe?


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Which usually adds a new GRUB2 on top of the current one.

Yes, but keep in mind that every Linux installation already usually installs GRUB2, so you have to explicitely tell it not to. Options like this are in Debian and Ubuntu installations.

You expect too much of this OS. If it would be as smart as a US air force pilot, then it would probably have much less issues than it has right now. The only thing that will happen is that your UEFI will set the Windows boot manager to the default thing to boot from, which means it will boot directly into Windows 10, without being able to choose any of the Linux installations in the actual GRUB2 menu. What you have to do then is changing the correct partition which inhabits the correct GRUB2 as the primary source of booting in your UEFI. You might be forced to do this every time your Windows 10 does a so-called “startup repair” which happens when your PC gets e.g. shut down during the Windows 10 boot process.

Yes, but it does not have anything to do with boot order.

Again, nothing to do with the boot order.

Here is what you have to do:

  1. Install Windows 10 on sda1.
  2. Go to your UEFI (spam DEL or F12 during boot) and change the priority of sdb1 to #1.
  3. Install second GNU/Linux on sda2 but forbid it to install GRUB2.
  4. Boot into sdb1, do whatever you want to do in GRUB Customizer. Probably the first thing would be adding the OS on sda2 to the GRUB2 menu.

If you somehow fail to succeed on number 3 by letting the new installation set a new GRUB2 then come back and I will explain how to fix that.


Well, then, if I understand you right, couldn’t I just exclude sda from BIOS boot order completely?

And, if I understand correctly, aren’t all GRUBs written into the MBR of the hard drive where the OS is? If that is true, wouldn’t that GRUB2 just be sitting quietly if sda is excluded from booting?

Finally, how different is it to alter BIOS and UEFI? I guess I gotta read up on that, eh?


I would suggest you buy a cheap second-hand machine from ebuy to experiment with. As you seem unsure of skill-set and still attached to Windoze. Thus avoiding a costly mistake.

As Akito indicated, it is good practise to install Windoze first be it on the same disk (sda) or secondary disk (sdb). Micro$oft would see this as Disk 0 and Disk 1

Legacy or UEFI install is dependent on your current machine specs, as early W7 was legacy mode only, while later versions involved into a hybrid UEFI, hence W8 then W10 being developed as true UEFI OS.

Run these command in a terminal

  • inxi -Fxz

  • [ -d /sys/firmware/efi ] && echo “Installed in UEFI mode” || echo “Installed in Legacy mode”

This will list your full machine specs and whether it is currently legacy or UEFI, so you’re able to make an informed decision on how to proceed. :sunglasses:

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For the sake of keeping it simple, I assumed your laptop has a UEFI, because you intended to install Windows 10 on it and if it has the necessary specs to run Windows 10, it almost certainly will have a UEFI. On the other hand, what @anon56357095 said is correct. I would follow his advice, if you want to be extra sure, though I don’t think you need to spend additional money for trying out stuff. I would only advise actually buying some playground to experiment on, if you really really need your computer every single day for a 100%. Assuming you need to spend maybe 2 days (worst case scenario) to make it work, it’s not an issue, except in the situation mentioned in the previous sentence. The good thing is that computers aren’t smartphones. It’s not like pushing the wrong button or flashing the wrong firmware can hardbrick your device into oblivion. Everything on a computer is reversible, except you explicitly destroy the hardware one way or the other.

Again, these assumptions put too much weight into boot order and boot exclusion. It doesn’t really have anything to do with how GRUB2 will be installed/not installed.

It’s barely different. The biggest point you need to make is that once you decide to go one way or the other, you have to keep going this way: E.g. GPT partitioned HDDs for UEFI, MBR partitioned HDDs for BIOS, etc. You can read up how it works in some online guide. There are enough for sufficient basic understanding. You don’t really need to know a lot, it’s enough if your HDD is GPT, if your laptop is actively using UEFI (CSM being off), then everything will sort itself automatically when installing Linux/Windows.


Gentlemen, I think I have a Eureka moment coming.

First, we’re talking about a desktop, Intel DH77EB, and using the commands that @anon56357095 suggested, is booted in Legacy mode. A search online shows that this board has serious UEFI problems, so let that one go.
Back to Linux. If I install other distros on sda, they will all have their own GRUBs.
Therefore, to get all my OSs listed, all I gotta do is run something like Grub Customizer in each distro, search for bootable OSs and list them. Boot order, as @Akito said, no longer matters if every GRUB has been updated and I stay away from Win 10.
Do I have that right?

As to @anon56357095’s point, I already have an old laptop with 2 GB RAM and 80 GB hard drive. I think I will put Deepin on that one to play around.


If you allow them to, yes. But as suggested earlier, you should try to install them without letting them install their own GRUB2s. I know for certain that Ubuntu and Debian always give you those options, don’t know how easy it is to disable that within other distributions.

Sounds like too much work for a too little result. It’s unnecessary, as explained below.

Technically, it does not matter if you do it like this but it’s a tedious way of handling the issue and not really what should be done, because there are more reasonable ways. All you have to do is have only 1 bootable GRUB2 on a single disk and that’s how the boot order within your BIOS doesn’t matter, since it will go through the list of disks until it finds a disk with the boot sectors filled i.e. where GRUB2 is. So if you disabled the GRUB2 installations during the OS installations, you are almost ready to go. All you would need to do is running Grub Customizer on sdb1 to add the newly installed Linux.

You might want to look up if and if yes, how much, it even works with BIOS instead of UEFI.

I think it would be better to run Deepin on a newer system, because it is not exactly made to be slim. Other than that, I used this OS and it was pretty nice. In fact, it features one of my most favourite terminals of all. I use it on my current Debian 10 installation, as well.
Since it is your old laptop anyway, you might as well try it, though, and see how it runs and what it does offer.


Hi cliffsloane,

This simplifies most install issues.

I had an old laptop that had very easy access to the HDD tray, (pre UEFI). Over the years I had accumulated a number of 80Gb to 160GB HDD’s. I would swap the W7 HDD’s to whatever flavour of Linux I had install to their own HDD I wanted.

As grub is loaded to each separate disk with own unique handshake from machine and disk.

This method allowed me to keep the original W7 HDD, then take out the windies HDD, put in clean HDD and install Ubuntu, Debian, CentOS, Fedora, OpenSUSE or any of their derivatives. Can’t vouch for Arch or Gentoo, during this period had real problems with them.

If you have a spare HDD, take out the windies HDD and install whatever flavour of Linux that has taken your fancy.

The same method will work for your desktop, as it prefers Legacy mode. But as it is still your Sunday best, do not fix what is not broken. :sunglasses:


As Akito has indicated your 2Gb of ram laptop will struggle to run Deepin, as it is allegedly resource hungry. Openbox or LXDE would be more prudent, unless you can upgrade to 4Gb of ram, sounds like a DDR2 version.

Use liveCD/USB to run this command or pull bottom panel and inspect ram module.

  • sudo lshw -class memory

  • Search name, model for how to do this or on Youtube

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