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.DMG Files

The .DMG file extension stands for "disk image" and is a file type used by the Apple OS-X operating system on all of the Powerbook and i-Mac platforms.

Generally .DMG file are used to archive and share information that would otherwise be stored on a physical CD or DVD. In many cases a .DMG file will be used to distribute software - generally as a download from an online source.

.DMG files are created by the "Disk-copy" function within the Mac OS-X operating system. The operating system creates a mountable disk image which is basically a "virtual" disk on your desktop which you can use to store applications and/or other bootable files. In the simplest terms it is as if the application or bootable information were stored on a physical disk - you would be able to launch and install applications from a .DMG file in the same manner as if you had a physical CD or DVD in your DVD drive.

The .DMG extension replaces earlier version of the Apple .IMG extension which was used by older Apple Operating Systems - .DMG files are not backward compatible with older versions of the disk image function of older Mac operating systems.

Opening .DMG Files

Generally you must have two things in order to open a .DMG file - an i-Mac or other Apple product and the OS-X Leopard operating system. If you have an older OS 9 version of the Mac operating system you may be able to open the .DMG file using the developer version of Disk Copy (version 6.4), or a beta version of the unreleased 6.5. However either version can only open uncompressed .DMG images. If you are dealing with a .DMG that has been compressed it is next to impossible to open it with anything other than the tools contained in the OS-X operating system - regardless of what version of the Disk Copy that was used originally to create the file.

If you are a Mac user running the Leopard OS-X operating system and still cannot open a .DMG file you may also be dealing with a totally different set of issues. You may have a problem with the file association between the .DMG file extension and the operating system. This could certainly be the case if you have partitioned the hard drive or your Apple product and are running the Windows Vista operating system in parallel to the Leopard operating system.

With the ability of new Apple products to run the Windows Vista operating system, Mac users are now beginning to experience some of the challenges that PC/Windows users have had to deal with for year - the WINDOWS REGISTRY.

If you are having problems opening file extensions it may be that Windows Vista is causing some of the problems. As PC users will know, most file extension-related errors can be easily resolved by running a Windows Registry Optimizer which cleans the Windows Registry and repairs many of these types of problems. These programs also tend to keep the Windows Registry working efficiently, speed up the operating system and generally keep the computer functioning smoothly.

.DMG Files and Windows Operating Systems

It is worth noting that although .DMG files are designed primarily for the Apple platform - there are programs such as TransMac and MacDrive that will open a .DMG file in the Windows operating system environment. These third party utilities can convert .DMG files into standard formats (such as .ISO) that can be interpreted by Windows based applications. Once the .DMG file has been converted into a format understood by Windows applications, the .DMG file can be mounted or burned onto any CD or DVD.

Mounting Problems With .DMG Files

There was an issue related with the 2007-004 Security Update for the Mac OS X 10.4.9 which had to do with the procedure of mounting the .DMG files after the update was implemented. In order to resolve the issue simply implement the patch provided by Apple.

Security Risks With .DMG Files

Be wary of opening .DMG, or any other archive file for that matter, sent by anonymous individuals as e-mail attachments or downloaded off the Internet. There have been cases where attachments disguised as .DMG files were actually viruses that were waiting to be activated when the file was launched. Opening unknown .DMG files can present the danger of virus or malware infection. Before opening one of these file extensions ensure it comes from a source you trust, that you have good anti-virus, anti-spyware, spam controls, privacy software, a registry cleaner and trusted data recovery tools activated and protecting your system.

Be sure to regularly scan attachments and all files in your computer system with an up to date anti-virus application or anti-spyware software, and ensure that it is really safe to open the .DMG file.

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