Inside the Dell PC Restore Partition

An Exploration by Dan Goodell
The Backup Image

The majority of the space in a DSR partition is occupied by a backup image.

An image is a file containing a compressed snapshot of the operating system partition, which can later be extracted to recreate a clone of the original partition. Think of an image like a zipfile, just on a grander scale. You probably know that with WinZip, PKZip, and other zip programs, you can compress groups of files and even entire directories into one zipfile, which can later be unzipped to restore all the encapsulated files and even the directory structure. An image is like a zipfile: it's not an exact duplicate of the original files, but it contains within it the means to restore exact duplicates--in this case not just a set of files, but an entire partition. Like a zipfile, an image is meant to be for storage--an archive. Like a zipfile, you can't directly use an image. To make use of a zipfile, you must extract the files from within it. To make use of an image, you must extract the partition within it onto a hard disk.

Readers may be familiar with this image/restore concept from commercial programs like Symantec/Norton Ghost, Acronis True Image, PowerQuest Drive Image, TeraByte Unlimited's Image for DOS/Windows, and others.

When Dell builds a computer to be equipped with DSR, one of the last steps in the build process is to create an image of the main XP partition--after any additional software and hardware (plus drivers) ordered by the customer has been installed. Note that this means each image is, in effect, tailored to the customer. Dell does not keep copies of these images. If you delete your DSR partition, Dell cannot send you a copy of what was in it.

The image file is named fi.gho and stored in the DSR partition. The entire partition is "hidden" to make it difficult for the customer to accidentally erase it. If needed, the customer can later use this image to return XP to its "as-shipped" state.

Due to filesystem considerations, very large images may be split into a group of files. Note the image consists of the entire fileset, and no one file in the set is usable by itself. If the image consists of a group of files, the first file is fi.gho, and the rest of the files are named sequentially, starting with fi000001.ghs.

The image in a DOS-style DSR partition is in Ghost 2003 format. The image in a WinPE-style DSR partition is in Ghost 8.3 format. These images are not compatible with Ghost versions 9 or 10!

DSR achieves a different result than installing from a Dell XP Reinstallation CD. The CD is essentially a regular Microsoft XP CD that is bios-locked to a Dell computer. It will install a basic XP operating system without the additional software and drivers Dell may have included on the originally shipped system. After installing from a Dell Reinstallation CD it may be necessary to reinstall some drivers and/or programs. In contrast, DSR will restore XP with the additional software--just like the computer was when originally shipped.

(Note to reader: DSR returns XP to the state it was in when Dell shipped the computer, so any programs the customer may have installed afterward will still need to be reinstalled.)

The DSR process wipes the hard disk's second partition (which in a stock Dell system is the main XP partition) and refills it with the contents of the image. Note that DSR only refills the partition, it does not alter the disk partition layout. This means that if the partitions have been resized or the disk repartitioned, the new partition layout will not be undone by DSR.


author: Dan Goodell

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