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.
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Reader Comments (Page 1 of 1)
Ron said 4:14PM on 6-16-2005
Actually, the description on how to use Disk Utility needs be more explicit to avoid confusion.
After Disk Utility is opened, if you don't select any item and click on 'New Image' or use the menubar 'Images -> New -> Blank Image ...', you will get a popup menu which gives allows you to select the location for the image in the top half, but the bottom half will only have three selections: 'Size', 'Encryption', and 'Format'. Note that in this case, you will only have two possible selections under 'Format': 'read/write disk image' and 'sparse disk image'.
However, if after opening Disk Utility, you select one of the disk images on the left-hand side first before doing the above, or use the menubar command 'Images -> New -> Image from Folder' or 'Image from *volumename*', you will get the same popup menu with the location selection on top, but below will be only two selections: 'Image Format' and 'Encryption'. Note that now under 'Format' will be four options: 'read/write', 'read-only', 'compressed', and 'DVD/CD Master'.
The implication is that you can only make certain disk images if you already have all the data present.
Thus, if you wish to use 'DVD/CD Master', you will have to put together a folder or disk image of everything first, allowing for some extra space for use by the formatting program.
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C.K. Sample, III said 4:14PM on 6-16-2005
This was based on my last entry on this which talks about first selecting the disk to be copied.
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Jeff said 4:14PM on 6-16-2005
So I've been trying to copy a store bought DVD using OS X, but Disk Utility is showing little love.
If I use the 'DVD/CD Master' image format, Disk Utility is creating a .cdr file. The dvd player will attempt to play it, and then crash after stumbling around for 30 seconds.
If I use the 'read only' image format, Disk Utility will create a .dmg file, but the same dvd crash results.
What am I doing wrong?
thanks,
love this site!!
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C.K. Sample, III said 4:14PM on 6-16-2005
Hey, Jeff. That's odd. Not sure why you're having the trouble (unless it's because you don't have a built in DVD burner; maybe that limits it). Try using DVDBackup, which I mention in today's installment to download the DVD into a folder, then use New Image from Folder in Disk Utility to create a disk image.
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Mario said 4:14PM on 6-16-2005
thanks for the clear and useful tutorial. I didn't know that you had to do it this way to create an image. I was stupidly trying to find out how to do it with Toast....snifff...
I still don't see where is the real difference between creating a .dmg or a .cdr image (the one you get when you use the option CD/DVD Master)...any idea what's the difference?
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sabino said 4:14PM on 6-16-2005
On Mar. 12 2005 Mario included the following in his post:
- "I still don't see where is the real difference between creating a .dmg or a .cdr image (the one you get when you use the option CD/DVD Master)...any idea what's the difference?"
This is of interest to me also.
I was purposefully searching for specific info or details on the distinction. What are the positive features and/or disadvantages of one image format over the other (.dmg vs .cdr)? Thank you in advance to all who offer assistance and clarification.
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