Dual Windows 10 installation

Hi everyone,

I would like some input of the community here to determine what is the best way to achieve the following goal :

I would like to set up a PC so that I have 2x Windows 10 OS's and a 1x Windows 7 OS (each in its own partition), but in set up such a way that the OS's cannot see each other at all (to keep them completely separate), preferably by hiding the partitions of the OS's that weren't started up (like with grub4dos, for instance ?). Then add a boot menu so that I can select the OS that I want to boot up.

How would I go about achieving this ?

(P.S. : maybe our beloved L1 Tech masters could make a nice video showing us all how to do this properly ? ;o) )

I'm sure that a lot of modern motherboards have such a feature built into the BIOS. At least when I was booting from different OS's before, I was able to select which before it would boot into any of the OS's that I had installed, like yourself, I had 3 OS's installed.

As for hiding the partitions, I'm not 110% sure about that, I mean I'd just google the crap out of that, personally. I'm confident that there's a way around it, but I'm not entirely sure how you'd go about doing that, I am sorry that I'm not much use on this part.... But I may look it up myself because I'm curious now, so if I find anything useful, I'll be sure to inform you of my findings...

I'm NOT 100% sure about this, but one way I can think of off the top of my head is by going into the disk management application in each OS, then click on the 'change drive letter' and then the 'remove' option, provided you know which drive in which OS it is that you'd like to remove..... But I'm not 100% sure this will work, I mean it's just an idea, if you wanna test it out for yourself, that could be s possibility? - If not then I can only suggest hope that someone else on this forum knows what to do. Or just keep looking into it..

I am sorry I can't be of any more help than that.

The only questions I have is... Why would you want 2 copies of Windows 10? Also may I be nosy and ask why you're installing Windows 7 too? ... You can see why I'd ask such questions.

The way I always fool proof my multi OS installations is by detaching the non-essential drives and only leaving the one drive for installation of said OS. This way you can just go into the boot menu upon post and just select which drive you want to boot into. That said, I really hate partitions...really hate them, they cause more problems then they solve in my line of work, especially when you don't get the benefits of actual drive speed and pfff forget about redundancy and aggregation.

Isn't that the only fool proof way? I do that too, it's so easy and effective! :D

Oh s**t, that's something I overlooked, he was talking about partitions... In that case, I don't think my above suggestion about trying to remove the drive letter would work, I'm not entirely sure, but I too don't really bother with partitions unless I have to for some weird reason. Just organise everything in some neat and tidy folder system and it's just as good.

  • In terms of triple booting the OSes on the same physical disk, is a pain to set up and requires a lot of technical knowledge but is possible.
  • An OS can be described as an instantiation of the files on a file system. Thus, it is not possible to make an operating system running on a disk not able to see the contents of the disk that it is running on. There are situations where another operating systems may use an unfamiliar file system or be encrypted, but every OS can fundamentally see the disk+partition structure and hence is able to modify the contents of the other file systems/partitions arbitrarily.
  • Argon's suggestion (removing drive letters) is the closest thing that is possible to effectively make each Windows installation ignore the others. Even then, they are not "invisible" to each other, but merely agree to ignore each other and it is fully possible, perhaps likely, for a Windows 10 rollup update to bork the shared bootloader thus making the other 2 systems unbootable. It would be up to you in this situation to understand what has happened and to fix it yourself.
  • The only way to actually make sure each OS cannot see the other is shu_kaze's suggestion of keeping the OSes on separate devices and unplugging the ones not in use. Alternatively, you could use specalized hardware (Add-in cards) to boot each system from a seperate device and make sure each OS does not have the storage controller drivers the other OSes are attached to. Such a setup would be... pointlessly complicated.
  • The shared OS-level shared bootloader is the most strait-forward way of adding multiple operating systems.
  • Technically, it is possible for the UEFI to start the boot loaders of different operating systems, cache the settings in NVRAM, and for each boot loader to be unaware of the other operating systems. This works well for Windows + Linux or different distributions of linux, however Windows' UEFI bootloader has reserved locations where it must be stored and the location of the related BCD store is hardcoded in the bootloader. The idea is to keep the bootloader in one of two locations and have it staticly read dynamic configuration settings from a single Boot Configuration Database (specific to BIOS/UEFI booting modes) that would be aware of different ways the system could be booted, such as multiple Windows installations, recovery partitions, linux, legacy (Windows XP) boot loaders etc.
  • Key point: Since the location of the BCD store is hardcoded in the bootloader, this implies that every Windows installation must be registered properly in that BCD store in order to get booted. This practically guarantees that a Windows 10 update will bork the other OSes at some point (since they rely on that specific BCD store to boot). This is "easily" fixable, but annoying.
  • It is probably possible to configure independent BCD stores or create a hirearchy somehow or w/e and Microsoft does do this in their downloaded Windows 10 x86+64 ISO images since there is a menu that is only aware of either the x86 or x64 image if UEFI booted, or both if BIOS booted. I haven't figured out how to replicate this configuration.

To add different OSes to a BCD store, you can use MS's bcdedit tool.

bcdedit /?

Don't use the Windows 7 version of the tool on a BCD store created by Win 8 or above. A newer version of the tool can be downloaded from MS's ADKs and there are also many many third party alternatives, some of them graphical .

Oh totally forgot. So the best way to achieve what you are trying to do is a completely different approach.

Just use a T2 hypervisor like VMWare Workstation or Oracle's Vbox.

Then you can have them all fully independent and it is trivial to switch between the different OSes. Workstation has better performance than vBox and there is also the T1 Hypervisor project called QubesOS that focuses on virtual machine isolation using (mostly) Xen. It should support IOMMU for native graphics performance in a dedicated VM.

I don't want to run a guest OS inside a host OS for these 3x specific OS's, I want the FULL set of resources available for each OS, so separate OS's each in their own partition seems like the right solution. I will also need 1 extra partition to house the boot manager / boot menu system (like grub4dos, if that one is able to chainload Windows 10 and properly boot it ???), so that would mean 4 primary paritions (which is doable from what I have read on the webbernet, 4 primary paritions is the maximum).

(P.S. : I know that this is possible with older Windows OS's - like WinXP, for instance : I had a triple OS/partition laptop set up like that - but what I need to know is if this is possible with Windows 10, and how to do this properly)

Just use boot to VHD feature.

You can also use disk imaging tools to clone your OS installs to VHD files and then boot from them.

from each OS vhd you can easily control which partitions are visible through Disk Management utility.

What's nice about this setup is you can copy the vhd files and if you want to restore to a "clean" OS setup you just swap out the backed up vhd file. As for performance issues with VHD I haven't experienced any degradation, you don't need super fast SSD either.

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