Clone, Wipe, or Image Media Using dd to Create RAW Disk Images

Clone, Wipe, or Image Media Using dd to Create RAW Disk Images

I recently came across five Windows machines I needed to get working. These were all to be used for the same purpose and thus I would have had to do the same work five times over. I decided to do the work once and then just clone the original disk using dd on Linux.

What follows are a number of example usages of the dd utility:

  • Make an ISO from a CD/DVD:

    dd if=[device] of=disk.iso bs=2048 conv=sync

  • Overwrite a disk with random data:

    dd if=/dev/urandom of=[device]

    One could use /dev/zero instead of /dev/urandom if they just wanted to zero out a disk.
    Darik’s Boot And Nuke might be a better tool for this.

  • Clone a partition:

    dd if=[device partition source] of=[device partition destination] bs=4K conv=noerror,sync

    Create unformatted partitions first.

  • Clone a disk:

    dd if=[device source] of=[device destination] bs=4K conv=noerror,sync

  • Create an image from a disk:

    dd if=[device source] of=[image destination] bs=4K conv=noerror,sync

  • Restore an image to a disk:

    dd if=[image source] of=[device destination] bs=4K

    .

  • Create a compressed image from a disk:

    dd if=[device source] bs=4K conv=noerror,sync | gzip -c > [image destination]

    It would be a good idea to have your image name end with .gz so you later remember it is a compressed image and also clear out temporary directories.

    Adding --fast to gzip will not stress your CPU as badly (good for netbooks and the like). Adding --best to gzip will give you the best compression but drastically slow you down.

    On a well-traveled filesystem zeroing out the free space can lead to huge space savings. In Linux you can use cd [mounted filesystem] && sudo dd if=/dev/zero of=delme-0 bs=1M &> /dev/null ; sudo dd if=/dev/zero of=delme-1 bs=1 &> /dev/null ; sync && sudo rm delme-1 delme-0 on the mounted filesystem (if you have multiple partitions you should do it for each) while Windows offers sdelete -z [drive letter]:. Depending on the amount of free space this could take a good long while.

  • Restore a compressed image to a disk:

    gzip -d -c [image source] | dd of=[image destination]

If you do not have a working Linux installation you can always use a Live-CD. Use fdisk -l or GParted to figure out what a device is named.

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