I want to clone my entire hard drive to a new hard drive or a new machine

There are many different reasons to make an exact clone of your hard drive. Suppose your laptop is damaged and you must send it in for repair. In the meantime, you not only have to borrow another computer for the duration of the repair, you also don't have your data, applications and work environment exactly as they were on your machine. This lack of organization can be very frustrating and inhibit your productivity. When you get your machine back from repair, you have to deal with locating any modified documents on your loaner computer and copying them to your original computer. Also, Apple recommends that you backup your data before sending in a machine for repairs because they are not responsible for lost data.

In this situation, it would be ideal to simply copy off the entire contents of your hard drive to an external hard drive — to create a "bootable clone" of your production machine. You can then boot a loaner machine from this bootable clone and work from it as if working from your original machine (note this caveat on computer-specific preference files).

When you need a complete, simple backup of your entire hard drive:

  1. Launch Carbon Copy Cloner
  2. Choose the volume that you want to clone from the Source menu
  3. Choose a properly-formatted volume from the Destination menu
  4. Select "Temporarily archive modified and deleted items" from the preconfigured settings menu
  5. Click the Clone button

If you want to update your cloned volume in the future, simply re-run CCC with the same settings and CCC will update the backup volume with only the items that have changed since your last backup.

Use Setup Assistant or Migration Assistant to move data from an older Mac to a new Mac

Another scenario in which it would be desirable to do a full-volume clone is when you have purchased a new Mac and you would like to move everything from your old Mac to your new Mac. When you get a new computer from Apple, though, it has a specific version of OS X installed on it, and further, a specific "build" number. Your new Macintosh cannot boot from the older version and build of OS X that is installed on your older Mac, so simply cloning your old Mac onto your new Mac won't work. Due to this limitation, we recommend that you use the Setup Assistant application (runs on your Mac's very first boot) or the Migration Assistant application to migrate content from your old Mac to a new Macintosh. You can migrate either directly from the hard drive installed in your old Mac or from a backup of your old Mac (e.g. if your old Mac's hard drive had died). Once you have migrated your user accounts and applications using Setup Assistant or Migration Assistant, you can continue to use Carbon Copy Cloner to back up your Mac to the same backup volume that you were using for the old Mac.

Apple Kbase #HT2186: Don't install older versions of Mac OS than what comes with your computer
Apple Kbase #HT2681: What's a "computer-specific OS X release"?
Apple Kbase #HT3322: Mac OS X 10.6: How to use Migration Assistant to transfer files from another Mac

"I bought a previously-owned Mac that's newer than my old Mac, but not brand-new. Can I use CCC to clone my older Mac to this Mac?"

If several OS X updates have been posted since the newer Mac originally rolled off the production line, then you will probably have success cloning your older Mac to the newer Mac. When migrating your old Mac to your newer Mac, be sure that your old Mac has been updated to at least one later release than what initially came on the newer Mac. For example, if your new Mac came with 10.7.4, update your old Mac to 10.7.5 before migrating. Determining whether this type of clone will work for you is really easy — simply boot the newer Mac from your older Mac or from a backup of your older Mac:

  1. If both your old Mac and your newer Mac have Firewire ports, boot your older Mac into Target Disk Mode by holding down the "T" key on startup, then attach your old Mac to your new Mac with a Firewire cable. If not, attach a backup of your old Mac (or your old Mac's hard drive in an external hard drive enclosure) to your new Mac with a Firewire or USB cable.
  2. On the newer Mac, open the Startup Disk preference pane in the System Preferences application and set the old Mac's volume as the startup disk, then click the Restart button.

If the newer Mac booted from your old Mac's installation of OS X, launch CCC then clone the older Mac's disk to the newer Mac's internal hard drive. If the newer Mac could not boot from your older Mac's installation of OS X, use the Migration Assistant to transfer your user data and applications instead.

Apple Kbase #HT1159: OS X versions (builds) included with Intel-based Macs
Apple Kbase #HT2191: Mac OS: Versions, builds included with PowerPC Macs (since 1998)