NWA-PCUG Newsletter Article, April 2012
Backup – Image, What’s the difference?
By Phil Sorrentino,
President, Sarasota PCUG, Florida
December 2011 issue,
Sarasota PC Monitor
president (at) spcug.org (click to email author)

This topic can be very confusing because of the similarities and the differences between backups and images. Backups and Images are similar in that they are both copies of something. The difference is in the “what” and the “how”. Normally, a backup is thought of as a copy of a file or a folder or a collection of files and folders (that is the “what”). The backup copy is just a copy, an exact duplicate and is not processed in any way (the “how”). The backup files can be used by any programs that could use the original files. The reason for having a backup file is to restore a file if it is accidentally destroyed or deleted.

An Image, on the other hand, is a copy of the Operating System and all of its components (referred to as the Operating Environment), as they exist in the memory of your operating computer (that’s the “what”). The Image can only be created by an imaging program (the how), and the image created can only be used by that same imaging program. The reason for having an image is to be able to re-install your “Operating Environment” if, or rather when, a virus or hardware problem makes your system unusable.

The topic can also be confusing because people, and even the literature, often use the terms backup and image in confusing ways. Often you will see or hear the term “backup image” which is meant to refer to a copy of an image. Well, an image is already a copy of something, so is this an image or is it a copy of an image? In order to keep things straight, I have tried to use the term “backup” to mean an exact copy of a file that needs to be saved. (I know that sometimes backup copies are “zipped” or compressed to save space, but those files are no longer exact copies of the originals and are not directly usable, so I would not call them backups, I would have to call them “zipped backups” or “compressed backups”, to be accurate.) And I use the term “image” to refer to the resultant file (or file collection) that is produced by an imaging program such as Ghost, or Acronis True Image, or Macrium Reflect, or even Windows 7.

To be completely protected against potential problems (viruses and/or hardware problems) you have to address both issues, backup and image. You have to backup all of your important files, those that you really do not want to lose, and you have to have an image of your Operating Environment for re-installation when needed. (Just as a point of interest, Windows 7 includes the ability to do both, via the Backup & Restore Control Panel.)

The files to backup are those that you have created or collected, such as your pictures, music, videos, Word documents, and spreadsheets. Any file that you would really be hard pressed to reproduce, if it was lost, is a good candidate for backup. How often to backup is dependent on the file in question. Files that are changing daily should probably be backed up daily, but files that don’t change need only be backed up on some weekly or monthly schedule. For backups, in general, follow “Chicago Politics” advice and backup early and often.

Also, be aware that there are many ways of backing up your files since it is only a Copy operation. However, there are many programs that make the job quick and easy. If you have a folder of pictures and you only add a few pictures to the collection weekly, then there is no need to copy all of the pictures each week, you only need to backup the new pictures. Backup programs such as Microsoft Synctoy, and Synchromagic, check the collection of files to be backed up against the last backup and only copy the new files or those that have changed since the last backup. These programs make the backup process quick, efficient and so easy that you will probably do it often enough. By now you are probably feeling that you have got the idea of backup, but where do put these backup files? The best place for backup files is on an external hard drive that is normally not connected to the computer. Right before you are ready to backup your file collection, connect the external hard drive and fire-up the backup program and run the backup task. After the backup is finished disconnect the external drive and put it away in a safe place.

Creating an image is a little more difficult than creating backup files because imaging is not just a simple Copy operation. Because an image is a copy of your operating computer memory, the program must know a lot about the architecture of the memory. This is very specialized knowledge and is the essence of an imaging program. The imaging program must be installed on your computer for use in creating an image. And, it must create a bootable disk to be used when your system is not operating correctly. The image it creates can usually be put on a system drive (other than the C: drive), or an external hard drive, or a number of DVDs. The image created is usually a very large collection of files that may total from 20 to 60 GB. The imaging process can take many hours depending on the size of the image and the amount of compression that is selected. Imaging is a very lengthy process, and it creates such large files, so you probably only want to do it when absolutely necessary. A new image is only necessary when the Operating Environment changes, when you add or delete programs, or when you update your operating system. You may not add or delete programs very often, but the operating system is updated, at least monthly, so you might want to create a new image every 3 or 4 month or whenever a big change is made to the Operating Environment.

So you can see there is a great difference between Backup and Image. But, both are necessary if you hope to completely recover from a future hardware failure or malware infection.

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