This article is for an older version of CCC. You can find the latest version here.

One of the most common uses of CCC is to establish a bootable backup of an OS X startup disk, or to migrate from a smaller disk to a larger disk. The steps below will guide you through this common scenario. For more scenarios, see the "Example backup scenarios" section of the documentation.

  1. Attach your backup volume to your Macintosh. See the "Choosing a backup volume" section below for additional advice on this subject.
  2. If the new disk is not initialized, format it using the Disk Utility application. If you are backing up to a new, external hard drive enclosure, we strongly recommend that you repartition the disk as the factory-provided partitioning may cause problems using the disk as a startup disk. See the Formatting and partitioning a hard drive section of the documentation for step-by-step instructions.
  3. Launch Carbon Copy Cloner
  4. Choose your startup disk in the Source menu
  5. Choose your new volume in the Destination menu
  6. Click the Clone button

CCC's defaults settings are optimized for this scenario, so no custom settings are necessary.

Next steps

  • Verify your backup: Take some time to verify your backup when the task has completed.
  • Swap hardware: If you are migrating data to a larger hard drive, you can physically swap the two hard drives when the task has completed.
  • Update your backup volume: If you would like to update your backup volume in the future, repeat the cloning task in CCC using the exact same settings — CCC will copy only the items that have changed since the last backup task.
  • Automate your backup: CCC can keep your backup volume up to date without your intervention. Click on the "Schedule this task..." button to configure CCC to automatically update your backup volume on a scheduled basis, when the source or destination volume is reattached to your Mac, or manually when you feel like getting it updated.

Choosing a backup volume

The goal of backing up your data is to protect yourself from hardware malfunction and accidental or malicious deletions. To effectively protect your data from both of these scenarios, it is best to back up to media that is not physically located inside your Macintosh (e.g. to an external Firewire or USB hard drive, or to another Macintosh), but at minimum to another physical hard drive (e.g. not to another partition on the same hard drive). Additionally, you should choose media that allows you to boot your Macintosh from the backup. A bootable backup gives you not only a really easy way to verify the fidelity of your backup, but it also allows you to instantly regain productivity should catastrophe strike. Rather than spending your morning restoring your OS and data, simply boot from your backup and carry on with your business.

For general performance considerations, please see our in-depth analysis of the factors that will affect how long it takes to back up your data. Before you purchase a hard drive for backup, consider the following options:

Internal or external?

If you have a Mac with room for additional internal hard drives, you can use that space for your backup hard drive. I prefer external hard drive enclosures for portability reasons — I can easily swap a pair of external hard drives between office and home to have an inexpensive offsite backup solution. This also gives me the opportunity to easily leverage that hard drive to back up multiple Macs.

USB, Firewire, or eSATA?

Many hard drive enclosures have Firewire, USB, or both interfaces for connecting the hard drive to your computer. Either of these interfaces will work fine for backing up and safeguarding your data, however, PowerPC Macs cannot boot from USB-attached hard drive enclosures. While Intel-based Macs can boot from either, I generally recommend using Firewire for performance reasons. Backups over Firewire are always faster than backups over USB. eSATA is a newer connectivity option that is very fast, though not quite as flexible as Firewire or USB and is not typically bootable.

Where should I buy it?

Hard drive enclosures are not all built the same, some are not even capable of booting a Macintosh. I prefer to work with vendors that cater to the Macintosh market because I can get assurance that they have tested their products with Apple hardware and OS X.

We do not recommend purchasing a hard drive enclosure from Western Digital if you require a bootable backup. Many Western Digital hard drive enclosures cannot boot your Macintosh, and the SmartWare firmware will guarantee that the enclosure will not boot your Mac. Western Digital hard drives are fine, the enclosures should be avoided until their SmartWare offers the capability of booting Macs.

How big should the backup volume be?

The backup volume should be at least as large as the amount of data that you want to copy to it. If you're planning to make regular backups to this volume, a good rule of thumb is that the backup volume should be at least 50% larger than the amount of data that you're initially backing up to it. This allows for a modest amount of data growth and room for temporary archiving of modified and deleted files.

PLEASE NOTE: We strongly recommend that you find the means to dedicate a volume to the task of backing up your irreplaceable data. If you have data on your backup volume that exists nowhere else, it is not backed up! Whenever you target a volume for use with Carbon Copy Cloner, there is a risk that some files will be removed for one legitimate reason or another. CCC offers options and warnings to protect your data from loss, but nothing can protect your data from a misuse of CCC or a misunderstanding of the functionality that it provides.

Verifying your backup

When you have completed your initial backup, you should verify that it will be ready to come to your aid should disaster strike. Follow these steps to verify your backup:

  1. Launch the System Preferences application
  2. Open the Startup Disk preference pane
  3. Select your backup volume as the startup disk and click the "Restart" button
  4. When your Mac has finished restarting, choose "About this Mac..." from the Apple menu and verify that you are booted from the backup volume
  5. Launch a few applications and verify that your data is intact. If you are interested in getting a more in-depth verification of the integrity of your backup, see the "Calculate a checksum for every compared file" section of the documentation.
  6. Reset your startup disk in the Startup Disk preference pane to your original startup disk, then restart your computer

Related documentation:

The first boot from the backup is slower, and some applications open automatically

The first time you boot your Mac from the backup volume, the startup process may seem a little bit slower than usual. This is perfectly normal due to the additional background disk activity that is occurring. In particular, Spotlight will be very busy regenerating its index, a process that involves reading nearly every file on the new volume. When this disk activity has settled down, performance will be back to normal.

Also, starting with Mac OS X Lion, the "Resume" feature will cause some applications to open automatically when you start your Mac from the backup volume. The applications that open will be those that were open when your backup task was running, and that often includes CCC. The next time you restart from the backup (or restored) volume, only the applications that were open when you chose to restart will be launched on startup.

"Where is System Events?" messages appears on first boot

There are a handful of applications that will cause this message to appear on a freshly cloned volume — any application that loads on startup and makes a call to AppleScript can cause this. This isn't a bug or an indication of a problem, it's just a matter of the LaunchServices system agent being a tad slow at rebuilding its cache of application to file-type associations. If you click the Cancel button, the message will go away, and you shouldn't see it again the next time you boot from your backup.