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How to make an external hard drive bootable?

sviel2010 Posted messages 13 Status Member -  
sviel2010 Posted messages 13 Status Member -

Hello,

I have an external hard drive with a lot of data (3TB) on which I created and cloned the partitions of my internal drive. On my external drive, the volume is E:. This corresponds to my internal C:. I am not able to boot from E:. I also have another partition D: on the external drive and I do not want to lose the data on it.

Is it possible to simply make the E: volume bootable? It has Windows 11 on it (cloned from my C:). I also cloned the 2 partitions from disk 0 of my C:.

Thank you!

Stéphane

4 answers

  1.
    Panth33ra Posted messages 23162 Registration date   Status Member Last intervention   Ambassadeur 2 358
     

    Hello,

    Check this link to start the system on an external hard drive.

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    1. brucine Posted messages 25024 Registration date   Status Member Last intervention   4 181
       

      Hello,

      It's the snake eating its own tail; cloning the system disk to make the external disk bootable will start by formatting it while it is partitioned and contains data, and we understand that the cloning itself involves several partitions.

      Therefore, we need to back up this data elsewhere, clone it, then partition afterward and copy the data back, hoping that the boot manager will still allow booting from this partitioned structure and, more generally, will keep the other partitions accessible.

      At least up to Windows XP, it was easy to manually make any disk bootable by copying its files on it by copying the boot files and then editing the boot file; under Windows 10 and 11, I'm not sure, maybe by copying those same files and building the BCD a bit in that style:
      https://www.diskpart.com/fr/windows-10/creer-disque-dur-bootable-windows-10.html

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      1. sviel2010 Posted messages 13 Status Member > brucine Posted messages 25024 Registration date   Status Member Last intervention  
         

        Yeah. I have 3TB to copy elsewhere, which will be difficult.

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    2. sviel2010 Posted messages 13 Status Member
       

      Thanks! I read the procedure and it will erase all the data on the external drive. Not cool. I have 3TB to copy elsewhere if not.

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  3. steph810 Posted messages 1865 Registration date   Status Member Last intervention   152
     

    Hello,

    It's possible but you mustn't mess it up.

    You need to partition your 3TB drive to create a new one if you have the space, of course, to accommodate the new OS.

    It's a bit like a dual boot.

    I'm giving you a hint, but I'm not taking the risk—there's a lot of manipulation online; you need to have all the information beforehand, like your boot loader, boot manager, the reagent info, etc....

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    1. sviel2010 Posted messages 13 Status Member
       

      Yes, I did that and created an E: volume on the external drive where I copied my C: that contains my Windows 11, but in the disk manager, it is not indicated that my new E: is a "boot volume" unlike my C:

      How can I make E: a "boot volume"?

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    2. steph810 Posted messages 1865 Registration date   Status Member Last intervention   152 > sviel2010 Posted messages 13 Status Member
       

      ok, take a screenshot of the This PC window and tell me which drive is the old one and which one is the new one.

      And do you have the Windows !! folder inside the 3Tb drive?

       you want to open the Start menu and CMD as administrator and enter:

       bcdedit /set {bootmgr} displaybootmenu yes

      then

      Windows + R

      enter

       sysdm.cpl ,3
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    3. sviel2010 Posted messages 13 Status Member > steph810 Posted messages 1865 Registration date   Status Member Last intervention  
       

      Drive D contains my data that I cannot afford to lose. Drive E is a copy of C.

      D and E are on the external hard drive.

      I couldn't follow the requested procedure. I'm using Windows 11 and I don't see the menus as shown.

      Thank you!

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    4. sviel2010 Posted messages 13 Status Member > steph810 Posted messages 1865 Registration date   Status Member Last intervention  
       

      Also, the command does not work

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    5. sviel2010 Posted messages 13 Status Member > sviel2010 Posted messages 13 Status Member
       
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  4. fabul Posted messages 42189 Registration date   Status Moderator Last intervention   6 070
     

    Hello,

    Have you thought about checking if the 100MB boot partition is marked as Active first? (Maybe it only matters in MBR?)

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    1. sviel2010 Posted messages 13 Status Member
       
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      1. sviel2010 Posted messages 13 Status Member > sviel2010 Posted messages 13 Status Member
         

        On the D, there is my data that I want to keep, and on the E, a copy of my C which has Windows 11. All of this on the external drive.

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      2. fabul Posted messages 42189 Registration date   Status Moderator Last intervention   6 070 > sviel2010 Posted messages 13 Status Member
         

        You could copy your data to an internal drive while doing a Windows To Go (WinToUSB)

        That would be the simplest option.

        I can no longer find (or I didn't look hard enough) the "Active" Partition concept since I've been using GPT; it used to be simple to mark the right partition as active with a partitioning program.

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