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I need to do a full backup of a boot partition of Windows 7. I want to be able to restore it if needed.

My understanding is that the only way to do this is to clone the partition byte-for-byte using something like Clonezilla. (If I'm in error, please correct me.)

Question:

Can I reduce the size of the partition before cloning (in order to minimize the size of the clone image), then increase the size of the partition after the making the clone, and then decrease the partition to the smaller size if the clone ever needs to be restored? Will that work?

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  • You can copy as much or as little of a drive or partition as you want using most tools
    – Ramhound
    Commented Jul 19, 2016 at 21:35
  • @Ramhound Thanks. My premise might be incorrect. I thought that in order to backup (and restore) a bootable Windows partition (that can survive a format), you had to perform a byte-by-byte clone. Am I wrong? I hope so.
    – End Antisemitic Hate
    Commented Jul 19, 2016 at 21:39
  • @RockPaperLizard- You need only need the boot partition and the OS partition. Its up to you to verify the files are within the sectors you specify when you perform the sector-by-sector copy of a particular copy. You don't have to copy the entire partition or the free space to make the drive bootable.
    – Ramhound
    Commented Jul 19, 2016 at 23:44

2 Answers 2

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A byte-for-byte clone as you put it is quite inefficient and Clonezilla by default will not attempt to do such a thing. Instead it will attempt to copy just the files and data that was listed as being used on the hard drive to the backup medium to keep the backup small.

The only reason to reduce the size of the partition before starting the clone/backup is to ensure that you can restore the image on a smaller disk/partition. In other words, if your disk is 2TB large and you make a backup of it, you can only restore the backup to other 2TB or larger disks/partitions. Do keep in mind that, (at the time of this writing), if your 2TB image has only used up say 20GB worth of data, it will still require a 2TB or larger disk/partition to restore to; even though the backup/restored size was 20GB.

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  • Thanks Blerg! I think my premise was incorrect. Tell me if I now understand correctly: To clone a Windows 7 boot drive (using a Clonezilla Live CD) that is 2GB with 100GB of data (1.9GB empty), all you need is a destination media (USB stick, microSD card, hard drive, etc.) with 100GB of free space. When restoring the clone, all you need is any partition on any drive of 2GB or larger. Is that all correct?
    – End Antisemitic Hate
    Commented Jul 19, 2016 at 22:06
  • Your destination media will need to have enough space to contain everything when backing up. Clonezilla has an option to compress the backup, so you might get away with something smaller. For the restoration, you'll need something that is about the size of disk that you backed up. Clonezilla will NOT restore to a disk that is smaller than the image, even if there was empty space on the drive when the backup was taken. It's efficient, but a little bit flawed.
    – Blerg
    Commented Jul 19, 2016 at 22:09
  • "...need to have enough space to contain everything..." Including the empty space within the partition being backed up? "...will not restore to a disk that is smaller..." But will restore to a disk that is larger, correct?
    – End Antisemitic Hate
    Commented Jul 19, 2016 at 22:14
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    Yes, that is correct.
    – Blerg
    Commented Jul 19, 2016 at 23:02
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    @Ramhound I wouldn't say horrible. From what I can tell, it's the tools that it uses that force you to have proper sizes when restoring disks/partitions. Clonezilla is just a UI that then calls the other programs to do the work.
    – Blerg
    Commented Jul 20, 2016 at 0:44
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Microsoft came up with DISM that solves this issue entirely... DISM doesn't care about partition size but, obviously, you must ensure the backed up data will fit onto the smaller disk - i.e. Don't knowingly try to put 500GB worth of C: onto a new 250GB disk.

DISM is available through the WAIK (Windows Automated Installation Kit) kit and you can create bootable media so you can begin using such tools as DISM and DISKPART.

DISM captures only the files/folders in use and doesn't have any knowledge of the partition structure used.

DISM creates a .wim file that is essentially a compressed file but it retains all the files. folders and attributes/permissions on the original install. As an aside: 7-Zip now has the ability to open .wim files so, in an emergency, you can easily extract files/folders from a different computer.

When using DISM to restore the image you must pre-create the partitions you require (using DISKPART to create (a basic example) the system reserved partition and then the main C: partition) and then you can put the WIM file into your new C:. It is then recommended you then use the BCDBoot tool to copy the Windows boot files to the boot partition (System Reserved) which will allow your Windows installation to boot.

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