Make disk images from installation CDs before it’s too late

Make disk images from installation CDs before it’s too late
Mac Tip #542, 27 June 2012

If you buy a new Mac and want to install software you have on a CD or DVD you may find you can’t. Here’s why and how to deal with the problem before it’s too late.

Disk or disc? I use both forms interchangeably below. Apple reckon there’s a distinction, but really, who has enough time in the day to worry about it? I don’t.

Quick Start

  1. Insert a CD or DVD in your old Mac.
  2. Open Disk Utility.
  3. Select the disc and click the New Image button.
  4. Select a location for saving the disk image.
  5. Wait while the disk image is created.
  6. Eject the CD or DVD and store the disk image somewhere safe, ready for the new Mac.

If this Tip was useful, please leave a comment letting us know. Want more detail? Read the full Tip below.

Got installation discs?

If you’ve been using Macs for a while, you may well have bought some software that came on a CD or DVD. And if you’re sensible, you’ll have stored that CD or DVD in a safe place, in case you need to install the software again for some reason.

My personal collection includes iWork and Aperture, among others.

How will I install Aperture with no disc drive?

How will I install Aperture with no disc drive?

These days, of course, software is commonly delivered via the Internet, including through apple’s App Store. This Tip solves what may be a transitional problem.

Some new Macs don’t have disc drives

Let’s imagine that you buy a new Mac and of course you want to reinstall that software. Now you might have a problem. You see some of the newest Macs don’t include an optical drive.

Disk Images are virtual copies of physical discs

Examples of Macs without optical drives are the MacBook Air and the new MacBook Pro with Retina display. So here’s a tip for something to do before you dispose of your old Mac: make disk images from your installation CDs and DVDs. It’s easy, and here’s how.

Note: a disk image is just like a CD or DVD but without the plastic. It’s a sort of pretend plastic disc.

Select a disc and click New Image.

Select a disc and click New Image. Notice that I’ve already made a disk image of the iWork ’09 Install DVD. Its name appears in the list on the left of the Disk Utility window.

Make a disk image with Disk Utility

Every Mac includes an app called Disk Utility, so everyone can easily do this. Making a disk image is extremely simple. It takes only a couple of clicks and some waiting time.

  1. Open ApplicationsUtilitiesDisk Utility. The Disk Utility window appears.
  2. Insert the installation CD or DVD into the drive on your computer.
  3. After a few moments the disc you inserted should show up on the left-hand side of the Disk Utility window.
  4. In the Disk Utility window, select the name of the disc you inserted.
  5. In the toolbar of the Disk Utility window click the New Image button. A dialog box appears where you can choose where to save the disk image.
  6. Disk Images can be quite large. If you have limited Internet capacity avoid saving the disk image in a folder that’s automatically synchronised via the Internet (such as Dropbox). A good place to save a disk image is on an external hard drive.

    Choose where to save the disk image.

    Choose where to save the disk image.

  7. Select a location and click the Save button. Now your Mac has a lot of work to do so go and make a cup of tea or take the dog for a walk.
It will take a while to make an image of the Aperture install disc.

It will take a while to make an image of the Aperture install disc.

How to use a Disk Image

You may have already used disk images if you’ve bought software online. The filename usually ends in the .dmg extension.

Can’t see filename extensions such as .dmg or .doc? See the Related Tips section below.

  1. Find the .dmg file and double click it. The disk image mounts just like a CD or DVD.
  2. Click on the disk image where it’s listed in the Finder sidebar. The window for the disk image opens.
  3. Double click the installer file shown in the window, or follow whatever other instructions came with the original install disc.
  4. When you’ve finished with the .dmg file eject it by clicking the Eject arrow beside its name in the Finder sidebar.
Click the Eject button beside the name of the .dmg file to Eject it.

Click the Eject button beside the name of the .dmg file to Eject it. This looks just like a Dragon Dictate install disc, even to the CD icon in the Title Bar, but it was actually a .dmg file. Beside its name in the Finder sidebar is a small arrow for ejecting the disk image.

Be prepared

By creating .dmg files of install discs you can store the files on backup hard drives and then reinstall software any time without needing to use the physical disc. And that includes when you buy a new machine that doesn’t have a disc drive.

Related Tips

These older MacTips may also interest or help you:

Please let us know how this Tip helped you. To leave a comment if you’re reading this by email or RSS feed please visit the Tip at the MacTips website. There should be a link from the title.

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  1. Ryan Rood said:

    I forgot how to do this. Thank you for the detailed how-to

  2. Don Hinkelman said:

    On the “Be Prepared” section of this page on “Disk Images”, it mentions you can place a disk image on a backup hard drive. Only a hard drive? I would like to put it on a backup memory stick. Is that OK? And can I then boot/re-install from that memory stick?

    • Miraz Jordan said:

      You’d better check elsewhere about *booting* from a memory stick, but you can store disk images on a USB stick if you like. For example: make a disk image of the Aperture installer, store it on any device / medium with enough space to hold it. Use it as required.

  3. Stephanie Krishnan said:

    I did something similar except I used Toast to make ISO disks. They can be mounted and installed on a Mac.

    I’m going to bookmark this, however as it doesn’t seem to require any additional software!


    • Miraz Jordan said:

      Thanks Stephanie, that’s good to know. You’re right about the software – Disk Utility has been on every Mac for at least the last decade, probably longer. No need to go spending extra for this one. :-)



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