My laptop has 465 GB of C:(windows partition) and 465 GB of D:(empty) drive. C: drive is 183 GB full, D: is empty. I want to clone entire C drive to my new 512 GB, MX500 crucial SSD such that SSD boots. Will unallocating the D drive make the bit by bit cloning process faster?

  • The best and most efficient way to image a partition on Windows has always been the native way Windows has always supported by capturing a WIM (see the Imaging section)
    – JW0914
    Aug 29, 2020 at 12:04
  • Thanks @JW0914 I will look into it! Aug 29, 2020 at 12:07
  • I'm not sure if it's the most efficient way, as AFAIK the tools do not support cloning directly to another disk – they insist on first creating a WIM image in some temporary storage before you can apply it to the target.
    – user1686
    Aug 29, 2020 at 12:11
  • @user1686 W/ Windows, cloning a drive is inefficient for a variety of reasons (requires additional steps if drives aren't the same size, requires 3rd party tools, isn't compatible with WinPE/WinRE, etc.), w/ 3rd party methods always fitting into one of two categories, either using Linux tools or DISM, which is the native way. While WIMs require a storage medium for the image, it can be saved to the drive with the imaged partitions, serving as a backup. Due to having this same conversation repeatedly w/ different users, I'm creating a question and answer that will address all of this.
    – JW0914
    Aug 29, 2020 at 12:27
  • @JW0914: Please do address this, as I'm fairly sure that the efficiency of file-level cloning by DISM is at best on the same level as $Bitmap-aware ntfsclone, and is very much outweighed by the need to store a huge temporary image file if it's only going to be used once. Especially if you're storing it on the same disk as the source, as that way you practically get only half the normal I/O speed.
    – user1686
    Aug 29, 2020 at 12:27

1 Answer 1


Partitions represent completely independent disk areas. If you perform a block-level clone of the C: partition, your cloning tool will only need to care about the 465 GB that was assigned to the C: partition, and won't even look at the rest.

(If you perform a block-level clone of the whole disk, it'll still spend 90% of the time cloning the C: partition, and then it'll quickly run out of space because your new SSD is smaller than the old HDD.)

What will make the process faster is either file-level cloning (e.g. WIM imaging) or filesystem-aware block cloning. For example, the Linux ntfsclone tool (which is used by CloneZilla) performs a bit-by-bit clone but it'll skip all blocks which have no files or other NTFS data stored on them. I would assume that commercial Windows tools do the same.

  • If I perform block level cloning of C:, my boot partition to my SSD, would I face problems while booting with the cloned SSD? Aug 29, 2020 at 12:41
  • @helloworld1e. Any boot issues that may arise can be fixed in WinPE/WinRE by issuing the following: BIOS: bootrec /fixmbr && bootrec /fixboot && bootrec /rebuildbcd || UEFI: bootrec /fixmbr && bootrec /rebuildbcd
    – JW0914
    Aug 30, 2020 at 11:48
  • @JW0914 I finally installed Crucial MX500 512GB today using "Acronis True Image for Crucial" cloning software, Windows booted fast and smooth after installing the SSD, no issues!! Aug 30, 2020 at 11:56

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