Questions about using Disk Utility

[plunar]

When I use Disk Utility to make an image of a DVD (data) for back up, does it make any difference whether I select root level of the DVD for imaging or just the data partition?

secondly, in the save box, i have the option to save as a "DVD/CD Master," and if i choose this the extension on the file will be .cdr instead of .dmg - does this have any purpose?

 

[devman]

When I use Disk Utility to make an image of a DVD (data) for back up, does it make any difference whether I select root level of the DVD for imaging or just the data partition?

secondly, in the save box, i have the option to save as a "DVD/CD Master," and if i choose this the extension on the file will be .cdr instead of .dmg - does this have any purpose?

this is confusing. If it's a data dvd, is there a reason you want to create a dvd image?

Yes, .cdr and .dmg are different. A .cdr (which you can simply rename to a .iso and use on a pc or linux box) is a dvd/cd image using that standards file format (e.g. ISO9660, Joliet, etc.). A .dmg is formatted HFS+.