Windows 10: How to install Windows 10 multiboot with a drive letter other than C?

Discus and support How to install Windows 10 multiboot with a drive letter other than C? in Windows 10 Installation and Upgrade to solve the problem; Since the prior thread asking about this is locked, I started a new thread. I have a multi-boot system, Win XP 32 bit, Win XP X64 64 bit, Win 7 Pro... Discussion in 'Windows 10 Installation and Upgrade' started by rcglider, Dec 4, 2020.

  1. rcglider Win User

    How to install Windows 10 multiboot with a drive letter other than C?


    Since the prior thread asking about this is locked, I started a new thread.


    I have a multi-boot system, Win XP 32 bit, Win XP X64 64 bit, Win 7 Pro 64 bit, Win 10 Pro 64 bit, each installed on a different partition, with a different partition letter, none of them C:. The C: partition only contains the boot files needed for multi-boot.


    For Win XP or Win XP X64 install, the partition letter is not changed to C:, so there is no issue there. For Win 7 Pro 64 bit install, I first boot into Win XP X64, and start the Win 7 Pro 64 bit install from Win XP X64, specifying the install partition by letter, in which case that instance of Win 7 Pro install will retain the partition letter I specified from Win XP X64 when I started the install. Win 10 install won't boot from Win XP X64, and attempting to install Win 10 from Win 7 assumes an upgrade instead of a clean install. The workaround was to install a second retail copy of Win 7 Pro 64 bit from Win XP X64, onto yet another partition specified by letter, then do a Win 7 to Win 10 upgrade on that partition, in which case Win 10 ends up with the partition letter I specified from XP X64 during the Win 7 install.


    Microsoft is able to do this in house in order to test Win 7 or Win 10 installed on partitions other than C: without going through the complicated process that I did, but the last time I checked, there is no end user documentation stating how such a multi-boot install can be performed, in spite of the fact that it's being done in house at Microsoft for testing.

    :)
     
    rcglider, Dec 4, 2020
    #1

  2. How to install Windows 10 (multiboot) with a drive letter other than C?

    About a year ago I created a multiboot system with Windows XP 32 bit, Windows Vista 64 bit and Windows 10 64 bit installed on a single SSD. It worked fine throughout the year and I could easily boot either of the 3 OS through the Windows boot manager, because
    each OS was installed with a different drive letter: XP is using X:, Vista is using C and Windows 10 was using D.

    However, a couple of days ago somehow my Windows 10 became dysfunctional and I had to reinstall. I deleted the partition, created a new one and installed it on the 3rd primary partition. However, no matter how I try, Windows 10 now picks the C: drive by
    default, causing it to destroy the Vista installation.

    I have checked the assignment of drive letters using the command prompt of the Windows 10 DVD, with the commands 'diskpart', 'select disk 0' and 'list volume'. This shows the following.


    How to install Windows 10 multiboot with a drive letter other than C? [​IMG]


    Apparently the assignment of the drive letters is also different from how I assigned them. But if Diskpart says the partition formatted for Windows 10 is assigned the letter F, and letter C is obviously already in use, why the hell does the Windows 10 setup
    assign letter C to Windows 10 during the setup?

    I'm lost. Can anyone help me recreate my multiboot system?
     
    CasparHeetman, Dec 4, 2020
    #2
  3. How to install Windows 10 (multiboot) with a drive letter other than C?

    HI Greg, thank you very much for your reply.

    Let me clarify the case a bit more. The reason I want W10 to use a different letter than C: is that I read in some articles that in a multiboot system, each Windows installation must have its own distinct drive letter assigned to that installation, because
    otherwise changes in one OS will affect the other and cause problems and failures.

    In practice what I have done is install XP first on the first partition - X:. on the SSD. And when I boot XP, it confirms that it is installed on X:, the system drive. After that I copy the Vista partition from my old hard drive to the SSD and update the
    BCD. The old Vista installation on the old HD has C: as its assigned drive letter, so that must be the same for the copy. This is confrmed when I shut down, disconnect the old HD and boot the Vista copy, it says it is installed on C:. The XP partition has
    another drive letter assigned to it. On the whole Vista runs smoothly and I can succesfully boot XP whenever I want to. Lastly I install W10 on the 3rd partition. The setup goes smoothly. When setup is finished W10 says it is installed on C:. The other partitions
    have other drive letters assigend to them.

    When after this I try to boot Vista, it says it is damaged and needs to be repaired (although SSD checks show the SSD's state is fine: no damages). I let Vista auto-repair itself by booting from the Vista DVD and boot Vista succesfully afterwards. However,
    when I try to boot W10 after this, it fails and also needs to be repaired. I boot W10 from the W10 DVD and auto-repair. And when I try to boot Vista after that, it is once again damaged. So it seems to me that somehow Vista and W10 are in conflict with one
    another and the only reason I can think of is that they are both assigned C:. Meanwhile Windows XP, being assigned X:, is unaffected and runs smoothly. My analysis is then that no two Windows OSs can both be assigned the same drive letter (e.g.. C) at the
    same time or one of them will fail, like what I read in some articles. Is that correct?

    However, I want a multiboot system with XP, Vista and W10 each installed on the same SSD and be able to alternatively boot one or the other. So now I'm looking how to achieve that: either by

    1. having W10 installed with drive letter D (or any other) or by

    2. changing the drive letter of the existing Vista installation to something else than C.

    A third alternative would be to use a 3rd party boot manager, but I would rather not be dependent on 3rd party boot managers.

    How can I, given this situation, create this multiboot system?
     
    CasparHeetman, Dec 4, 2020
    #3
  4. How to install Windows 10 multiboot with a drive letter other than C?

    How to install Windows 10 (multiboot) with a drive letter other than C?

    Normally you'd install a post-Vista OS from boot and it would assume C when booted and another letter when the other OS' is/are booted. But Vista is fixed due to the cloning (or being Vista) and so I'd try from Vista Disk Mgmt deleting and recreating the
    Windows 10 partition, then run the WIndows 10 media from Vista doing a Custom install, choose the partition you created for it, and it should claim another drive letter that isn't taken.

    Again, it does this because it's being run from Vista which already has claimed C and therefore cannot claim C as it does normally but will take the next drive letter that isn't taken by the system as Vista sees it.

    You could just overwrite the Windows 10 partition but it will create a windows.old folder archiving the old install and isn't as clean so I'd delete it in Vista Disk Mgmt first, then create a new partition to install it to when running WIndows 10 media or mounted
    ISO from VIsta as a Custom (NOT Upgrade) install.
     
    Greg Carmack - MVP, Dec 4, 2020
    #4
Thema:

How to install Windows 10 multiboot with a drive letter other than C?

Loading...
  1. How to install Windows 10 multiboot with a drive letter other than C? - Similar Threads - install multiboot drive

  2. If I install the game on a drive other than C drive and do gaming then how many GB of C...

    in Windows 10 Gaming
    If I install the game on a drive other than C drive and do gaming then how many GB of C...: If I install the game on a drive other than C drive and do gaming then how many GB of C drive is required for Windows setup for good gaming? What would be your advice?...
  3. If I install the game on a drive other than C drive and do gaming then how many GB of C...

    in Windows 10 Software and Apps
    If I install the game on a drive other than C drive and do gaming then how many GB of C...: If I install the game on a drive other than C drive and do gaming then how many GB of C drive is required for Windows setup for good gaming? What would be your advice?...
  4. Microsoft store wont install anywhere other than C: Drive

    in Windows 10 Installation and Upgrade
    Microsoft store wont install anywhere other than C: Drive: I need help my pc storage is all into my D: drive and yet your microsoft store wont let me change directory where he install file always on C: this is not a one time proble ive seen LOT and LOTS of post concerning this probleme and none of them worked for me why does...
  5. Microsoft store wont install anywhere other than C: Drive

    in Windows 10 Gaming
    Microsoft store wont install anywhere other than C: Drive: I need help my pc storage is all into my D: drive and yet your microsoft store wont let me change directory where he install file always on C: this is not a one time proble ive seen LOT and LOTS of post concerning this probleme and none of them worked for me why does...
  6. How to change SYSTEM drive letter from C to any other letter (A or Z)

    in Windows 10 Drivers and Hardware
    How to change SYSTEM drive letter from C to any other letter (A or Z): Hello! I have a dark desire and some OCD related spasms to make some changes on how Windows10 is arranging the drive letters in explorer.exe, i would really appreciate any guide, advice or joke :) on this. Short story I want to change the default system partition letter...
  7. System Reserved on drive other than C.

    in Windows 10 Installation and Upgrade
    System Reserved on drive other than C.: Hi all, Just installed windows from a usb on to a computer I just built and was just about to stripe two drives together, however one of the drives has a System Reserved partition so I cannot do this. Why did the partition go to that drive and not my C drive? Can I move...
  8. How to install Windows 10 (multiboot) with a drive letter other than C?

    in Windows 10 Installation and Upgrade
    How to install Windows 10 (multiboot) with a drive letter other than C?: About a year ago I created a multiboot system with Windows XP 32 bit, Windows Vista 64 bit and Windows 10 64 bit installed on a single SSD. It worked fine throughout the year and I could easily boot either of the 3 OS through the Windows boot manager, because each OS was...
  9. Cannot move or install apps on drive other than C:

    in Windows 10 Software and Apps
    Cannot move or install apps on drive other than C:: I have a small SSD that has windows installed, and a larger SSD and HDD that I use to store the majority of my programs/files. When I try to install a game like Sea of Thieves or Zoo Tycoon on any other drive than my C drive, it fails during the install step. I have tried...
  10. Install on another drive other than C?

    in Windows 10 Installation and Upgrade
    Install on another drive other than C?: So i have the latest windows 10 version, but i cannot seem to install apps to any where except the C drive. And the option to change is disabled. See image attached. Why is it disabled? How do I get it to work ? I am on windows 10 pro if that matters. 33611