Article, December 2007
Using Imaging Software For Backup
By Brian K. Lewis, Ph.D.,
Member of the Sarasota Personal Computer Users Group, Inc., FL
Obtained from APCUG with the author's permission for publication by APCUG member groups.
There are many hard drive backup programs on the market that tell you that they can make an "image" of your hard drive. This allows you to restore your programs and data in case of a hard drive crash. They also will transfer everything on your hard drive to a new drive. Among these backup programs are well-known names such as Symantec Ghost, Acronis True Image, R-Drive Image, Image for Windows, Paragon Drive Backup and a host of free imaging applications. In terms of making a complete backup of your hard drive (operating system, applications and data), they are very successful. However, what happens when your hard drive crashes or you decide you want a new computer? Will these applications solve the problem of restoring your applications and data quickly and easily? Let's look at the generic methods they use for these situations.
Basically each of these programs makes a "bit-map" copy of your hard drive that is usually compressed and may be encrypted. This, I'm sure, is a statement that needs some explanation. First, the words "bit-map." Everything stored on your hard drive is encoded in the binary computer language. This language is composed of 1's and 0's only. This limitation is imposed by the electromagnetic character of hard drives as well as the "pits and hills" of optical media. So a "bit" is one character, a one or a zero. A computer word is a "byte" which is composed of eight "bits." The imaging software is examining every bit on your hard drive and copying it to the backup media. In order to save space, the bit-map is compressed before it is written to the backup site. The method of compression varies with the software used. Sometimes, the compressed file may be written in a proprietary format that can be read only by the specific application that originated the backup. In other words, Ghost's image file can't be read by any program other than Ghost.
So now we have a bit-map image of our hard drive on whatever we chose for the backup media. In my case I use external hard drives. If I were to store the backup on a partition of my original drive and that drive failed - I would lose the backup. So store it somewhere else if you ever expect to need it.
What does this image file contain? It has the entire contents of your hard drive. That means operating system files, including the Windows Registry, all of your software applications and all of your data. It also has all of the hardware driver information that Windows needs that relates to your hardware. That includes drivers for your motherboard and processor, network card, USB ports, printers, scanners, video cams, etc. This is a very important point, especially if you want to clone your drive to a new computer. More about that later.
Since an image file contains a complete copy of your hard drive it can be very useful in restoring individual files. It can also be used to restore an entire hard drive in case of a drive failure. There are several methods available for this process. Some image file programs allow you to create a bootable disk (floppy or CD-ROM). When the computer is booted from this disk, it will install the image file program and can then be used to restore all the files on the backup. This includes the operating system files. In other cases you have to first install the operating system and then the image file program before you can restore the rest of the files. In both cases, it is not necessary to reactivate Windows as changing the hard drive is not enough of a change to cause Windows to demand that you go through reactivation.
Microsoft instituted a copy protection process called "activation" with the release of Windows XP. This has been continued with Vista. The activation of Windows plays a very important role in any situation where hardware changes are made to your computer.
If you have a brand name system that you did not have to activate it only means that the manufacturer pre-activated it for you. In the activation process, a small file is placed on your hard drive, and sent to Microsoft, that contains the information related to these ten items:
IDE Adapter (effectively the motherboard)
Network Adapter (NIC) and its MAC Address
RAM Amount Range (i.e., 0-64mb, 64-128mb, etc.)
Processor Serial Number
Hard Drive Device
Hard Drive Volume Serial Number (VSN)
CD-ROM / CD-RW / DVD-ROM
This file contains a number based on the identification of the first item in every category. The file also contains the complete product key for your Windows installation. Every time your computer boots, this hardware is checked to determine if any changes have occurred. You can make changes to your hardware. However, "substantial" changes will result in a notice that you have to reactivate Windows.
The XPinfo software, whose name is shown at the top of Figure 1, can read your activation file and compare it to the reported hardware. The report for my computer shows that none of the hardware has changed since the last activation. Also, in the figure you will notice that there are eight checked items out of ten. Should the figure drop below seven unchanged or never installed items, Windows would have to be reactivated. The interesting point is that the NIC or internet card carries three votes. Changing this card to a motherboard with a built-in NIC might put you on the way to reactivating Windows.
Suppose that you decide to move your hard drive to a new computer or you want to "clone" your old drive to a new drive in a new computer. Your hardware will have made a substantial change and it will be necessary for you reactivate Windows. But that is not the only catch in this situation. If you restore the entire image file to the new computer or simply clone the hard drive, the Windows Registry from your old computer will not have the correct hardware information. It may or may not boot. If it does boot you will receive warning after warning that files are missing. There will also be requests for driver disks for the new hardware. So when you move to a new computer, the only files in your image backup that can be used without difficulty are the data files. Even the applications that were running successfully on your old computer will really have to be reinstalled on the new computer. This is because the Registry not only stores hardware information, it also has all the information on the location of all files required to run your applications. Although you might think that the .exe file is all that is needed to run an application, you would be surprised at the number of subsidiary files that are required. Sometime, do a search of your computer for files with a .dll suffix. These are the library files that are required by applications running under Windows. These files are also shared by many different applications at the same time. There are hundreds of library files on any Windows computer. They make up a large part of the more than 2 GB of files in the Windows folder.
As long as you use the image file backup to restore files or hard drives in your original computer, it will work beautifully. The problems arise when you want to upgrade to a new system. Then, the image file is less useful.
Dr. Lewis is a former university & medical school professor. He has been working with personal computers for more than thirty years.
This article has been provided to APCUG by the author solely for publication by APCUG member groups. All other uses require the permission of the author (see e-mail address above).Click here to return to top