What is a disk image?
A disk image is an exact binary copy of an entire disk or drive. It is not just a collection of files or folders but is an exact duplicate of the raw data of the original disk, sector by sector. Since disk images contain the raw disk data, it is possible to create an image of a disk written in an unknown format or even under an unknown operating system.
A disk image file (or simply a disk image) is an exact copy of a disk stored in a file. This file contains all the information required to clone the original disk; boot sector, FAT, and all files and folders along with their attributes. See Disk Images Explained for more information about disk image files.
A disk image is a file that contains the file structure and contents of a storage device such as a CD-ROM, DVD, or hard drive partition. Disk images are frequently used to create exact duplicates of volumes. They are especially useful for producing boot disks and software installation media. On some systems (e.g., all versions of Mac OS X) it is possible to mount a disk image, allowing you to access its contents as if it were a normal (though typically read-only) volume. There are many different disk image formats, and with the exception of those that are self-mounting, you will most likely need a separate utility to view and copy their contents or create new images. For example, either Disk Copy or StuffIt Expander 5.0+ are required to access most Mac OS disk image files. In Mac OS X, you can easily create disk images using Disk Utility, which is located in /Applications/Utilities. OS X handles the .dmg format natively; if you need to mount a disk image of a different format, try usin
Why is it needed? Answer: A Disk Image is a mirror of your logical drive or physical device that is stored in one large file. A Disk Image file can be useful when you want to back up the contents of the whole drive, and restore it or work with it later. Before you start recovering deleted files, it may be a good idea to create a Disk Image for the entire drive, if you have enough space on another drive. The reason for doing this is for insurance. If you do something wrong while recovering the files (for example, recovering files onto the same drive they came from), you will be able to recover these deleted files and folders from the Disk Image that you have wisely created. Active@ UNDELETE provides extensive functionality to recover files from a Disk Image. You can create an image of a logical drive, a device or a partition. Save the disk image as one large file or split the image into chunks the size you prefer for later use. When creating a Disk Image, it stores in at least two files
A real Atari disk is a complex mess of adhesive magnetic stuff, made sense of by a dedicated floppy disk controller and then made useable by a computer in the disk drive. All these things boil the structure of the real disk down to a specific number of useable sectors for each recording surface, each of a fixed length. A disk image contains only the part of a real disk the Atari Computer can see or use, its fully processed data. An ATR disk image contains 16 bytes of data that identify it as an Atari disk image, and the remainder is every byte of useable data off the original diskette, stored in the original order it was stored on the disk.
