Carbon Copy Cloner

Download CCC 3 now! (Tiger and Leopard)

Clone, synchronize, backup. Schedule and forget it. Try it 'til you trust it.

The key to a successful backup plan is to actually do the backups regularly. When left to a human, the task often gets tacked on to the end of a very long list of other things to do. When you eventually have a catastrophe, the data is simply gone. You know that feeling -- you just lost six years of family photos. Your kids being born, their first birthdays, their first everything. The answer to this is consistent and regular backups, placed on a schedule and handled automatically by your computer.

CCC 3 features an interface designed to make the cloning and backup procedure very intuitive. In addition to general backup, CCC can also clone one hard drive to another, copying every single block or file to create an exact replica of your source hard drive. CCC's block-level copy offers the absolute best fidelity in the industry!

CCC Features

√	Complete, bootable backups
√	Simple interface for indicating exactly what you want to back up
√	Restore using the same process used for backup
√	Backups are non-proprietary, so you can browse them or use them with Migration Assistant
√	Fast, incremental backups copy only the items that have changed since the last backup
√	Archival backup archives items that have been deleted from the source
√	Support for block-level disk-to-disk clones
√	Support for backing up across the network to another Macintosh
√	Back up to hard drives or to disk images
√	Schedule backup tasks on an hourly, daily, weekly, or monthly basis, or you can indicate that a backup task should run when the backup device is attached (e.g. an iPod). You don't even need to be logged in for your backups to occur!
√	CCC recognizes iPods specifically, allowing time for the iPod:iTunes synchronization to complete
√	Built-in software update feature notifies you when updates are available

See the complete release history here.

Carbon Copy Cloner is now available as a Universal binary. As with previous versions, Carbon Copy Cloner is released as uncrippled shareware — try the full-featured product until you trust it, then consider a donation to the Bombich Software Tip Jar.

CCC and Data Fidelity

A couple years ago some folks published a pair of fairly extensive reviews of backup software for Mac OS X. Titled "The State of Backup and Cloning Tools under Mac OS X" and "Mac Backup Software Harmful", they concluded that many Mac OS X backup utilities (including CCC) were not up to the task of adequately backing up files on Mac OS X. Metadata, it claimed, was often lost in transit. While this article had the beneficial effect of making many developers pay closer attention to Mac OS X filesystem metadata, it also had the unfortunate side effect of causing unnecessary panic among most end users. Here's why:

Many filetypes include support for metadata. For example, TIFF includes support for hundreds of different kinds of metadata like the location where the picture was taken, author name, camera specifications, etc. These metadata are stored inside the TIFF file, so it's rather difficult to lose these during a backup. Filesystem metadata, on the other hand, include things like permissions, ownership, creation/modification date, and access controls. There are also "extended" attributes -- data associated with a file that is not stored in the file itself. Resource forks fall into this category. All of these filesystem metadata reside within the filesystem directory, separate from the data fork of the file, therefore it is possible to lose this information when transferring files from one volume to another.

Obviously the preservation of both kinds of metadata is important, however there was never cause for concern about the loss of filetype-specific metadata. I'm also not trying to suggest that they intentionally instigated concern about filetype-specific metadata loss, but the difference is lost upon the layman if you don't call out the two types of metadata explicitly.

Due to the concern raised by this article, and because it is not updated on a regular basis to keep track of developer responses, I have decided to post the outcome of CCC's "Backup Bouncer" test here. Backup Bouncer is an automated test suite developed by Nathaniel Gray that determines how well Mac OS X file metadata is conserved. To analyze the accuracy of your backup, you would first use the test suite to create a "source" volume that contained several samples of typical and edge-case metadata. Next you would use your backup utility to backup the data to a "target" volume, and finally you would use Backup Bouncer to compare the two volumes and report how well metadata was preserved.

The following report compares two volumes after Carbon Copy Cloner copied the "CCC_Source" volume to the "CCC_Target" volume. The "Cloning method" in CCC was set to "Backup everything". Tests in blue are tests that I added to the test suite to make it even more thorough.

bash-3.2# ./bbouncer verify -d /Volumes/CCC_Source/ /Volumes/CCC_Target/
Verifying:    basic-permissions ... ok
Verifying:           timestamps ...
  Sub-test:    modification time ... ok
ok
Verifying:             symlinks ... ok
Verifying:    symlink-ownership ... ok
Verifying:            hardlinks ... ok
Verifying:       resource-forks ... ok
Verifying:         finder-flags ... ok
Verifying:         finder-locks ... ok
Verifying:        creation-date ... ok
Verifying:            bsd-flags ... ok
Verifying:       extended-attrs ...
  Sub-test:             on files ... ok
   Sub-test:      on locked files ... ok
  Sub-test:       on directories ... ok
  Sub-test:          on symlinks ... ok
ok
Verifying: access-control-lists ...
  Sub-test:             on files ... ok
   Sub-test:      on locked files ... ok
  Sub-test:              on dirs ... ok
   Sub-test: on non-inherited acls ... ok
   Sub-test:    on inherited acls ... ok
ok
Verifying:                 fifo ... ok
Verifying:              devices ... ok
Verifying:          combo-tests ...
  Sub-test:  xattrs + rsrc forks ... ok
  Sub-test:     lots of metadata ... ok
ok

Flying colors! CCC passed every single test. I repeated this test using several other settings -- "Incremental backup of selected items", remote and local source and target volumes, PowerPC and Intel clients, Leopard and Tiger OSes. In every single case, CCC passed every single test. So there you have it! CCC is accurate *and* safe. Sleep well!