In this guide I’ll walkthrough what I did to get a 1TB spinning hard disk running Windows 10 cloned to a 256GB SSD using a Linux machine surrogate. I think these steps can be reproduced using some live USB distros as well. As a warning this will truncate recovery partitions.
Shrink the Data Partition
Before removing the disk from the host machine, boot Windows up one last time to shrink the partition down.
- Open ‘Disk Management’ from the Control Panel or Windows menu
- Right click the main data partition and select Shrink
- Shrink the volume to a size below the target disk size
- If successful skip the next section
Possible Limiting Factors of Shrinking
Windows stores some things at the end of the system partition which may limit the ability to shrink the volume. If the Shrink operation is giving a maximum shrink size that isn’t large enough, try the following and reboot.
- Disable page file
- In System->Advanced->Performance->Settings->Advanced->Virtual memory->Change
- Disable hibernation
- In an administrative command prompt use
powercfg /h off
- In an administrative command prompt use
- Disable fast startup
- Didn’t seem to affect shrink size but may help to stop corruption of the BCD
- Power Options->Choose what the power buttons do->Turn on fast startup (uncheck)
Once the source drive’s data volume has been shrunk appropriately, attach both the source and
target drives to a Linux machine. Identify which devices in
/dev/sd* are which by using
fdisk -l /dev/sda. You should see roughly the following for the source drive:
Disk /dev/sda: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disklabel type: gpt Disk identifier: 610F7F53-E81F-4587-873F-83AD7E58AE66 Device Start End Sectors Size Type /dev/sda1 2048 1026047 1024000 500M EFI System /dev/sda2 1026048 1107967 81920 40M unknown /dev/sda3 1107968 1370111 262144 128M Microsoft reserved /dev/sda4 1370112 2906111 1536000 750M Windows recovery environment /dev/sda5 2906112 293773311 290867200 138.7G Microsoft basic data /dev/sda6 1932173312 1934055423 1882112 919M Windows recovery environment /dev/sda7 1934055424 1953523119 19467696 9.3G Windows recovery environment
Verify that the end of the data volume is within the bounds of your target drive. In this case sectors are 512 bytes and the end of the data volume is at 293773311 sectors which is roughly 150GB, well within my 240GB SSD drive capacity. Note that there are still recovery paritions past the end of the data partition. These will get truncated in the following cloning process but should not affect the Windows installation.
Cloning with DD
Next begin a truncated copy of the source disk to target using dd. Use a block size and count
such that only the partitions up to and including the data partition are fully copied. For
simplicity I used the block size that
fdisk reported in and then used the End sector of my
dd if=/dev/sda of=/dev/sdb bs=512 count=293773311
Fixing the GPT
Performing a truncated copy of the disk will corrupt the GPT. Luckily this can be fixed using gdisk. Enter gdisk and perform the following operations:
- Delete any partitions after the data partition using
- Fit the GPT to the new disk size using expert
- Use the main GPT header to rebuild the backup with recovery
- Write the table to disk with
If at any point you screw up, you can always just copy the first 2048 bytes from the original disk to restore original GPT and start over.
Verify working NTFS volume
Attempting to mount the filesystem in Linux should succeed, or at least fail saying something about the filesystem being in an unsafe state due to fast startup or hibernation.
mount -t ntfs /dev/sda5 /mnt/test
In my experience this technique actually succeeded even if the system is in a lower power mode although probably this isn’t “recommended”.
Back to Windows
Attach the newly cloned target drive to the Windows machine and boot it. If booting fails
error codes like
0xc0000009 the BCD is likely corrupted. Booting into a
windows restore media and starting a terminal you could try doing a
chkdsk /f. If it deletes
a bunch of indexes that are outside the disk bounds then you likely did not shrink source disk
data volume sufficiently or you did not copy enough of the source disk to the target.