Super disk cloning

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With a new version of Mac OS X—10.4, “Tiger”—recently being released, a popular topic has been backing up your hard drive. As Joe Kissell noted in his recent Macworld excerpt from Take Control of Upgrading to Tiger , a vital part of any upgrade is making sure your important data is backed up. But even without a major OS upgrade in the wild, savvy users know that you should always have a good, working backup of your Mac’s hard drive.

One way many users get such a backup is to “clone”—make a mirror image of—their drive. Not only does this approach let you perform an Erase and Install of OS X, using Migration Assistant to restore your data and applications from the clone (as explained by Joe), but it also means that if anything should ever happen to your main hard drive, you can be up and running from the clone in no time. Unfortunately, because of invisible files and permissions issues, you can’t simply drag the contents of one volume onto another to get a good copy, as you could in Mac OS 9 and earlier.

In the past, my favorite utility for cloning my hard drive has been Carbon Copy Cloner; unfortunately, it’s not yet compatible with Tiger. On top of that, as great a utility as it is, some users find its interface a bit intimidating. Another option is Mac OS X’s Disk Utility, which can make copies of volumes, but its options are fairly limited. In searching for an alternative, I’ve recently found a new favorite: Shirt Pocket’s $20 SuperDuper! 1.5.5 (   ).

Like Carbon Copy Cloner, SuperDuper!—although I’m admittedly enthusiastic about the software, the exclamation point is actually part of its name—lets you make an exact duplicate of your hard drive; the resulting clone is even bootable. But what I like most about SuperDuper! is that it’s easy to use for the most basic functions while offering advanced features not found in Carbon Copy Cloner.

On the easy-to-use side, the interface explains, in plain English, what is going to happen, so you can be sure you’re actually doing what you want to do. For example, to make a standard clone (a bootable copy) of a volume, you simply choose the volume you want to be copied and the volume to which you want the copy to be made—you make these choices from pop-up menus arranged in a sentence that reads, Copy {volume name} to {volume name} . But just in case that isn’t clear enough, SuperDuper! then tells you what is going to happen:

SuperDuper's main screen.

If this is all you want to do, simply click the Start Copying button, provide your admin-level username and password, and let SuperDuper! do the rest; a progress dialog shows you the progress of the copy. The resulting copy will be an exact clone of the original—if the original volume was bootable, the copy will be, too.

However, SuperDuper! also provides a number of different ways to copy files and volumes, as well as several ways to customize the process:

Alternate types of copies In addition to the standard “Backup - all files” method of cloning a volume, SuperDuper! offers three other types of copies:

  • Backup - user files: This type of backup does not create a bootable clone; instead, it copies only user files—those files found in the /Users folder. This type of a backup is useful if you don’t need a full, bootable copy of your hard drive, but want to make sure you have a backup of personal data.
  • Safety clone - shared users and applications: This option copies all files from the source to the destination except user files (those in the /Users folder) and third-party applications. These files are actually shared between the two volumes (see below).
  • Safety clone - shared users: Identical to the previous option except that applications are copied, as well.

SuperDuper backup types.

The “Safety clone” feature is rather unique; it creates a copy of your existing drive except for user Home folders and (if selected) third-party applications, which remain only on the original drive; both volumes share those files. The philosophy behind such a setup is that if you need to install new software, or an OS Update, you would boot from the clone , install the software or Update on the clone, and then see if everything works fine—your personal data will be safe on the original volume. If no problems occur, you can later reboot from the original volume and install the software or Update there. If you do have problems, you can switch back to the original volume—which was untouched by the new software or Update—and proceed as if you’d never changed a thing; you won’t lose any changes to personal files you made while booted from the “safety clone.” (You can then erase the clone and create a new one.)

Interesting enough, as the screenshot above implies, the four standard backup types are actually provided by scripts built into the application. Advanced users can create their own scripts, based on or including the stock scripts, to further customize SuperDuper’s functionality to their needs.

Copy options If you click the Options button before starting your copy, you’ll see a number of options for the current copy operation, categorized into Before, During, and After the copy. For example, before the copy begins, you can have SuperDuper! repair permissions on the source volume. And power users and administrators will appreciate the “After copy” options: SuperDuper! can create a disk image of, or install a package onto, the destination volume, or even run a script that customizes the destination volume—great for deploying a standard image to many computers, as in a lab environment. You can also choose to reboot from the new clone after SuperDuper! is finished.

SuperDuper's backup options.

But for most users, the more important options here are the “During copy” choices:


  • Erase destination , then copy files from source : This is the standard clone method; the destination volume is erased and then the source volume is copied onto it.
  • Smart update destination from source : This option is useful for updating an existing clone, as it copies only those files that are new or changed since the previous copy was made, and deletes any files that are no longer on the original volume. In other words, it updates the clone so that it is again an exact copy of the original volume. (The results is exactly the same as if you’d done another “Erase, then copy” but is much faster.)
  • Copy newer files from source to destination : This option does not delete files from the clone that have been deleted from the original volume; it only replaces a file/folder on the clone if a newer version exists on the original.
  • Copy different files from source to destination : This option is similar to “Copy newer” except that it replaces a file/folder on the clone if a different version—older or newer—is found on the original volume.

Whichever copy method and options you choose, the “What’s going to happen?” summary will always explain exactly what is going to happen, so you can make sure you’re actually performing the desired action.

SuperDuper backup summary.

SuperDuper! remembers your settings the next time you launch it, so you don’t have to go back and set it up again each time. And if you find yourself performing several different types of backup operations with SuperDuper!, you can save your settings for each, and then load the appropriate settings when needed. SuperDuper! is also AppleScript-able, so savvy users can automate their copy operations using these settings files.

Finally, the SuperDuper! manual is comprehensive and understandable—something I always appreciate—and even includes a section on how to recover from a backup should disaster strike.

Taking into account its clear interface, excellent functionality, and informative documentation, I consider SuperDuper! to be a must-have utility for Mac OS X. The only major feature missing is the ability to schedule copy/clone operations—for example, I’d like to be able to tell SuperDuper! to automatically clone my hard drive every night at midnight. The good news is that Shirt Pocket has promised scheduling support in the next major update—which promises to make SuperDuper! even more of a Gem.

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