How to Copy your DVDs / CDs in OS X: Part 2

Yesterday, I started introducing you to the amazing disk copying capabilities of Disk Utility.  After you choose to create an image from device, a dialog will come up with several options while asking you for the location to save the resulting .DMG file. You have the option of selecting an image format and a type of encryption.  For simple backup purposes like copying CDs and DVDs, there is no real reason to select any encryption; however, I use this option regularly to back up financial documents and other sensitive bits reserved for my eyes only.  Choosing encryption will prompt you for a password, which you must submit in the future whenever attempting to mount the image.

Under "Image format" you have the option to select read/write, read-only, compressed, or
DVD/CD master. For our purposes here, DVD/CD master is the best choice, as it is the most conducive to burning copies of the disk. I tend to avoid using the compressed option, as it tends to slow down mounting of the disk image substantially; if I need the file to be compressed, I usually simply right click on the .DMG file and choose Create Archive to wrap it up in a zip file. 

Now whenever you need to create a replacement disk for that installation CD that has been sitting in the bottom of your desk drawer, sliding around with your thumb tacks scratching it into oblivion, simply launch Disk Utility, drag the DVD/CD master DMG file over into its sidebar, select the image file in the sidebar, and click the burn button.

Now, if you've made a backup copy of a commercial DVD, you will often find that the image weighs in at a much larger footprint than the 4.7GBs supported by your Mac's SuperDrive.  You can still mount this image and play it like any other DVD; however, if you want to actually make a burned DVD copy of the disk, then you have to go through a slightly different procedure, which I will discuss in tomorrow's installment.  Check back then.