What Is a Disk Image File and What Formats Can Be Used in Storing Optical Media?
Ever since people started using floppy disks, disk image files have become popular ways of storing and distributing all types of files. Whether you’ve tried installing a new operating system on your PC, setting up a virtual machine, making a bootable flash drive, or installing games from a CD, you’ve certainly used disk images before. You may even be familiar with some of the most popular image file formats, such as ISO, DMG, and IMG.
So, what exactly are disk image files? What are they for, and why do they have different formats? Let’s talk about it!
What Is a Disk Image File
Disk image files contain a copy of a data storage device such as a hard disk drive, CD-ROM, or DVD. These files are created as an exact duplicate of the original disk, where it captures all of its contents, including the file system structure, media files, program files, and boot sectors. Because disk image files are exact copies of a disk, these types of files also act as actual physical disks, which need to be mounted and unmounted before and after use.
A disk image file’s byte-per-byte disk copy is what makes it the perfect format for storing data, making backups, and distributing software.
When Do We Use Disk Image Files?
Since disk image files act just like a normal disk, disk image files are often used for various applications, including:
Awesome! But why use a disk image file over regular open and uncompressed files?
How to Read, Save, and Store Disk Image Files
Because disk image files act like disk drives, they cannot be opened or used just like any regular files or directories on your computer. To open a disk image file, you’ll first need to mount the disk image into your computer just like any other external drive.
On Windows, you’ll first need to locate the disk image, right-click and selectMount.
Once mounted, the disk image should appear on your file explorer as a disk. You should be able to open its contents and see all the files within the image.
Now, if you try to right-click on the file, you’ll notice thatRenameorDeleteisn’t an option. Likewise, adding a file to the disk image will also not work. To manipulate the disk image and the files within it, you’ll need a third-party application like PowerISO, Daemon Tools, and MagicISO.
You can, however, copy the files within the disk image and save them just like any other files on your computer.
You can also choose to burn the disk image file onto an actual disk if you want. Just right-click on the image and selectBurn disc image.
Remember to unmount the disk image files after use by right-clicking on the file and selectingEject.
You’ll want to unmount the image after every use, as disk image files are virtual drives that take up system resources when mounted. You’ll also need to unmount the disk image if you want to move or delete the file.
For Linux users, depending on the distribution, you may or may not have a GUI to assist you with mounting the disk image file. You can, however, use the terminal to mount and unmount a disk image.
First, you’ll need to make a directory where you will mount your disk image file. Open your terminal and use the following command:
To mount the disk image file, we’ll need to use the loop command and specify the file’s location using-o, followed by the directory we’ve just created.
To verify, let’s list the directory by using the command below:
As you can see, the terminal has listed all the disk image’s contents which means the mount was successful.
Don’t forget to unmount after use by using this command:
Note that it’s “umount” not “unmount”.
Of course, you can also verify if the unmount was successful by listing the files within the folder created.
As for Mac users, there are severalways you’re able to mount and unmount disk image files on macOS, such as using Disk Utility or through third-party applications. For example, let’s mount a disk in the terminal:
To mount the disk image file, macOS has a built-in utility tool known ashdiutil, which works with disk image files. First, let’s mount the file using the command:
To unmount the disk image file, use the command:
Common Disk Image File Formats
Disk image files have been used for several decades now. And with new tech platforms popping out, companies and organizations developed their own disk image formats for their specific products. As a result, there are well over a hundred disk image file formats for different platforms with various advantages and uses. Here are the most common ones you’re more likely to encounter.
Disk Image
Common Usage
Supported OS
General purpose disk image file for storing and distributing software
Windows, Linux
Disk Image file for distributing software to macOS devices
Used to install ARM-based operating systems
Compressed ISO format to save space for Playstation Portable games and emulators
Playstation Portable System Software
Disk image format for distributing Xbox games
XOS (XBox)
VirtualBox disk image for making virtual machines
Windows, Linux, macOS, Android
Why Use Disk Image Files
Disk image files are essential formats for making exact copies of a disk drive for backups, archives, and software distribution. They are unique to other file formats as disk image files ensure a “byte-per-byte” copy of a disk drive, including file structures, boot data, and configuration files.
This makes it easier for developers to copy their entire environment and ensure that everyone gets the software and all the files and configuration needed to make that software work. This is also great for anyone making backups, archiving CDs, and migrating their systems to new machines.
So, say goodbye to all those extra dependencies and the hassle of configuring software; disk image files are here to help.
Need to back up and restore Windows without backup tools? Learn how to make an ISO image of your Windows PC.
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