Question

I just cloned a hard drive partition (of Windows 10) to a new hard drive.

The thing is that I did it wrong and I just copied the data part, NOT the boot part. So now I have a new hard drive with a Windows copy with no boot partition.

I tested many tutorials, but the problem is that the bootable part NEVER existed on the new hard drive (so it can't be recovered!).

If someone knows how to create from scratch a new bootable partition for Windows 10. I have many licensed programs and lots and lots of configuration.

And if someone asks I just deleted all the data from the old hard drive (genius!), so I can't copy now the bootable disk partition.

Burgi

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asked Dec 5, 2019 at 11:16

1

Answer 1

There are general steps in the BCDBoot docs: https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/bcdboot-command-line-options-techref-di#repair-the-system-partition

UEFI

For UEFI the partition layout is documented at: https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/configure-uefigpt-based-hard-drive-partitions

Run diskpart. Select your target disk using list disk, sel disk ##, detail disk.
Create a new "system" partition of approximately 250 ~ 500 MB:
```
DISKPART>  create partition efi size=250
```
(A good minimum is 250~256 MB for a Windows-only disk, or 500~512 MB if you plan to dual-boot Windows and Linux.)

This step cannot be done using the graphical Diskmgmt.msc as it requires setting the correct GPT "partition type" ID.
Format the new partition as FAT32, and temporarily assign a drive letter for the next step:
```
DISKPART>  format quick fs=fat32 label="System"

DISKPART>  assign letter="S"
```
Install the Windows Boot Manager files:
```
C:\>  bcdboot C:\Windows /s S: /f UEFI
```
(Change C: to whatever drive letter is assigned to the OS partition at the moment.)

This will also generate a fresh Windows Boot Manager Configuration Database (BCD), and will automatically create a boot entry in your system firmware (named "Windows Boot Manager").

BIOS (aka CSM or "legacy boot")

For BIOS the partition layout is documented at: https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/configure-biosmbr-based-hard-drive-partitions

Steps 1-3 can also be done in diskmgmt.msc.

Create a new "system" partition of approximately 100 MB:
```
DISKPART>  create partition primary size=100
```
In legacy boot mode, this partition is no longer for EFI but merely for Windows alone (not shared with other operating systems) so it can be smaller.

Format it as NTFS and assign a temporary drive letter:

DISKPART>  format quick fs=ntfs label="System"

DISKPART>  assign letter="S"

Set the 'active' or 'bootable' flag for this partition (so that the MBR will know that it needs to load this partition's VBR):
```
DISKPART>  active
```
Install a whole-disk boot sector (MBR):
```
C:\>  bootsect /nt60 S: /mbr
```
Install a partition boot sector (VBR):
```
C:\>  bootsect /nt60 S:
```
Install the Windows Boot Manager files:
```
C:\>  bcdboot C:\Windows /s S: /f BIOS
```
(Again, replace C:\Windows with the actual path to your Windows installation as it is currently seen by the installer environment.)

answered Dec 5, 2019 at 12:05

grawity

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12

UEFI

BIOS (aka CSM or "legacy boot")

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