Demystifying The Disk Image

There is little that rivals the mystique of disk imaging. If you perform an internet search of the term “disk imaging,” you’ll find that though imaging products may be large in number, there is very little information available on how they work.

Is it the fate, then, of PC users everywhere to remain in the dark, ceaselessly wondering just how products like Laplink DiskImage, Acronis True Image and Norton Ghost magically create images of their PC, which they may save for later restoration?


After scouring the internet and picking the brains of Laplink’s finest software engineers, this Laplink copywriter has put together an explanation of the disk imaging process and publishes it now, here on this very blog, to spread the purifying light of knowledge to the far reaches of the PC user community.

Unveiling a Mystery: The Disk Imaging Process

A disk image, as it turns out, is just that – an image of your hard drive. It is a single file containing the entire contents of a data storage device, such as a hard drive, optical drive, etc., ending in a .dmg, .iso, .cue, .bin or .img file extension. This file can be stored either a compressed state, to save space, or a “raw,” uncompressed state. Whether the file of a disk image is compressed, along with the size of the hard drive, determines how large the file will be. Images that appear as a separate hard drive to the computer are called virtual hard drives, and end in .vhd.

Though there are many different disk imaging software products available all the market, they all essentially do the same thing (though some may do it faster and better than others). By creating complete sector-by-sector copies of a hard drive, its structure and all its contents, the average imaging product constructs a perfect replica of an entire drive – a replica that can be safely stored in case of catastrophe.

For those at all familiar with disk imaging, the terms “forensic imaging,” “differential imaging” and “incremental imaging” might ring a couple bells. Aside from having an intimidating amount of syllables, these terms describe different imaging methods.

Forensic Imaging: Creating a forensic image of a hard drive means that the imaging software will read each sector of the hard drive, rather than just the files themselves, to produce a complete image. Because a forensic image picks up and copies whole sectors of a hard drive, the image will contain all the hard drive information – this may even include deleted files and partial data.

Differential Imaging: A differential image is created to add changes to a previous general or forensic image. This kind of image identifies and makes copies of differences made to the hard drive since the first imaging, and adds those changes to the complete image. So rather than having multiple complete images, you have one complete image – a very large file, and then a image of only what has changed – a much smaller file.

Incremental Imaging: Similar to the differential image, an incremental image also takes note of changes made to the hard drive. However, an incremental image picks up changes from the last incremental image. In this case you have one very large complete image, and multiple smaller images of what has changed since the last incremental image. Incremental imaging is often performed regularly by users who wish to maintain a recent image of their hard drive.

Once an image of a hard drive or other storage device has been created, it can be used to restore to a computer to its former glory. Like some shining combination between an angel of mercy and the ultimate “undo,” imaging gives users the opportunity to resuscitate a PC from the edge of oblivion and start over with a clean slate. And really, what more could you ask for than a new beginning?

Want an Ultimate Angel of Merciful Undo for your very own? Try ours – New Laplink DiskImage with PCmover Image Assistant: For fast, easy and powerful hard drive imaging and restoration.

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