You can use DropDMG to create exact copies of CDs or DVDs, e.g. your Mac
OS X install discs or a bootable emergency CD for disk repair software
such as DiskWarrior or Drive
Genius.
- Set DropDMG to create a read-only .dmg image. A compressed
format would also work, but this is faster.
- Drag the CD or DVD icon onto DropDMG; it will create a device
image of the disc and save it as a .dmg file.
- Eject the disc.
- Drag the .dmg file onto DropDMG while holding down the Shift
key. This is equivalent to using File ‣ Burn Image….
- DropDMG will ask you to insert a blank disc; after doing so,
click the Burn button.
DVDs are faster to access than CDs. Thus, if you burn a DVD copy of an
emergency boot CD, your Mac will boot approximately 25% faster from the
backup than from the original CD. This can be a savings of a couple
minutes.