When writable CD’s and DVD’s, came onto the market in the nineties, they instantly became the most favoured choice for data transfer and back up, ranging from computer files to audio music. Right up to today, optical discs still hold the pole position market share compared to other storage media and the introduction of Blu-ray discs, capable of much higher storage capacity, indicate that optical discs will still be around for many years to come.
A major issue with CDs and DVDs is that the integrity of the data stored on them can be easily compromised from a simple tiny scratch on the disc surface leading to a partial or complete loss of the stored data. The best way to circumvent this inherent issue of the disc, is to back up the contents of a CD, DVD or blu-ray as an image file. A disc image is a single file containing the complete contents and structure as the actual physical disc.
There are several standard file formats for backing up the disc contents to an image file, these formats include ISO, DAA, CUE, NRG, BIN, MDF and MDS to mention but a few. Making an image backup of your CD or DVD is much simpler than one might imagine, all that is needed is suitable software with the correct functionality. There are two classes of software that can be used to create a disk image; specialised image making software and most modern disc burning or writing software.
Specialised image making software includes PowerISO, Alcohol 120% and Daemon-Tools. Apart from their main function of creating the software images, these software’s are able to create virtual drives that can be used to mount the images. This means that one can use the backed up image without burning them to a physical optical disc first. Examples of disc burning software that are also able to create images include Ashampoo, Nero, Roxio, Deep Burner, Apple Disk Copy and K3b for the Linux fans. Both the specialised disc imaging software and burning software listed above are available for free from their respective websites and repositories.
The internal work flow of imaging software is not overly complex. All it does is to emulate the actual disk writing device such as a DVD writer, but instead of writing the data to an actual black physical disc, it writes it into a computer file, this is what we refer to as the image file. Some of these software’s go a step further and eliminates the free, empty or error containing sectors from the disc in the image files, leaving you with a compressed version of the disc, therefore saving valuable storage space on the backup medium.
Having disc backups as images is advantageous because the images can be compressed, they can be used and accessed without burning them back to physical media again, they can be password protected and encrypted, data can be added or removed from the image if necessary before burning it to a disc again and because it’s a normal computer file it can be easy transferred across a network, or sent to the other side of the world faster than it would take by posting the physical disc.
On the flip side, it can take quite a long duration to create an image file bearing in mind that all sectors of the original disk has to be read first. Because it is a single file it can be easily deleted. Another disadvantage is that in case the original file contained a virus or any malicious program, mounting the resulting image or burning to a disk again might cause the host computer to be infected.
It is vital to ensure that adequate back up processes are in place for your vital information stored on CD DVD or blu-ray.
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