About Disk Image Types
Disk image software Active@ Disk Image supports backup type and raw type disk images.
Backup Disk Image is the default type and should be used in most cases. When Raw Disk Image type is not mentioned explicitly in this guide, we are referring to the Backup Disk Image. Another file format supported is ISO image. ISO images are used to store a copy of CD/DVD/Blue-ray disc in a file and stand apart from actual disk images.
Backup Disk Images
A Backup Disk Image contains only data found in used sectors of a hard drive. This is done in order to reduce the size of the disk image file and to reduce the time it takes to create the disk image.
One Backup Disk Image archive can hold data from several partitions from one or more disks. When you select a partition to be backed up, all current data will be saved into the disk image archive.
Data that is recognized as deleted files and unused partition areas are not recorded into the image. Windows pagefiles and hibernation file data are also excluded from a Backup Disk Image because they contain temporary information which is useless to keep and restore.
Active@ Disk Image can make a backup of any file system. If a partition selected for backup is formatted with a file system that is not supported by Disk Image natively (i.e. FAT or NTFS are supported), a sector-by-sector (raw) backup will be performed.
Keep in mind that this mode is different from raw disk images described below. The image of partition of unknown file system will be placed into .ADI file; the major difference from NTFS and FAT partitions is that it will contain all sectors of the partition - used and free.
Raw Disk Images
A Raw Disk Image contains an exact, sector-by-sector copy of a single partition or disk. A Raw Disk Image of a disk or a partition is a larger file than a Backup Disk Image of the same disk or partition and it takes a longer time to create.
A Raw Disk Image archive can hold data from only one disk; either a whole disk or one partition from a single disk. It cannot contain more than one selected partition. To make a Raw Disk Image of several partitions on various disks, you may create a separate Raw Disk Image for each partition.
ISO image is a standard format which contains an exact, sector-by-sector copy of an optical media as CD/DVD/Blue-ray disc. It is used automatically when a CD/DVD/Blue-ray disc is selected for backup. ISO image can be burned back to the optical media.
When to use Raw Disk Images
In normal conditions, you will likely use Backup Disk Images. A Backup Disk Image has the following advantages over a Raw Disk Image:
- A Backup Disk Image file is smaller than a Raw Disk Image file (while containing all your valuable and usable data).
- It takes less time to create a Backup Disk Image than it takes to create a Raw Disk Image.
- The Backup Disk Image process has advanced features like storing several partitions in one image, password protection and variable compression options.
Raw Disk Images are more helpful in a data recovery scenario. Here are some reasons why a Raw Disk Image is superior for data recovery:
- Data recovery technologies are based on searching the unused space on a partition for traces of deleted, lost or damaged files and folders. So-called "unused space" on a partition is not recognized by the file system and is not saved to a Backup Disk Image. However, this space might contain valuable data information and it is saved to a Raw Disk Image.
- The uncompressed Raw Disk Image file contains a sequence of sectors that is unchanged from the original. There are no headers or other application specific identifiers added. As a result, the Raw Disk Image can be viewed by any data rescue software as a mirror of your drive. If the integrity of the data on your live disk is questionable, you may want to experiment with the data on the partition image instead.
- If file size is an issue, a compressed Raw Disk Image may be used. Active@ Undelete is an example of data recovery software which can work with both compressed and uncompressed Raw Disk Images.
- Raw Disk Image have no regard for the file system type. During the Raw Disk Image recording process, all sectors are backed up. An image of any partition can be created and restored.
- If you want the data from a file to be restored from the disk image to the same exact location as they were before, then use a Raw Disk Image. A Backup Disk Image saves all current data but restores files to different sectors, allowing the partition to shrink or grow, depending on the size of the replaced file. In a regular situation, you should not be concerned about partition size. If the partition size is important, however, a Raw Disk Image is the solution.
About disk image file names
- Backup Disk Images
Backup Disk Images have the file extension .ADI.
All data is stored in one file or in a sequential series of numbered files. When the disk image is split into several files, additional file names are created by adding sequential numbers to the original name.
Here is an example: If you save a Backup Disk Image with the name MyImage, the application creates a file named MyImage.adi at the specified location for the first image file. If you have configured the operation to split the image after a fixed file size, or if the image is split automatically, the next file name is MyImage1.adi. The next file name after that is MyImage2.adi, and so on.
- Raw Disk Images
Raw Disk Images have the file extension .DIM.
A Raw Disk Image consists of two files: a configuration file and data file. The configuration file describes the disk or partition geometry and keeps the image description. This file has the .DIM extension. When verifying or exploring a Raw Disk Image, select this file.
The raw image data files have numerical extensions starting from .001 added to the whole image name.
Here is an example: If you save a Raw Disk Image with the name MyImage, the application creates a file named MyImage.dim. This is the configuration file. Data is stored in a file named MyImage.dim.001. If more than one file is created, the next file is named MyImage.dim.002, and so on.
- ISO images
ISO images have the file extension .ISO. One .ISO file contains image of one optical disc, thus for every optical drive selected there will be a separate .ISO file created. Backup folder