Note: The topics in this article are not relevant to APFS-formatted destination volumes that have CCC snapshot support enabled. For those volumes, CCC leverages snapshots to implement the SafetyNet functionality, and the snapshots aren't affected by any of the shortcomings described here.
Disk images are not bootable backups. To create a bootable backup, you must back up to a hard drive that is attached directly to your Mac. We recommend that you only use a disk image if you are backing up to a network volume connected to via ethernet, and we recommend using locally-attached storage for your primary backups.
Reminder: Recovery HD volume cloning is not applicable to APFS-formatted destination volumes (i.e. Catalina and later)
Carbon Copy Cloner offers complete support for archiving, cloning, and recreating Apple's Recovery HD partition. See the Cloning Apple's Recovery HD partition section of CCC's Disk Center documentation for instructions to create a Recovery HD volume on your backup disk.
A welcome side-effect of cloning one volume to another is that the files on the resulting volume are largely defragmented. While fragmentation is not as significant of an issue as it used to be (e.g. in the Mac OS 9 days), people that have begun to fill the last 10-15% of their boot volume may see some performance benefit from defragmentation. If you find yourself in this situation, this is also a really good time to consider migrating to a larger hard drive altogether, or to an SSD, which is not affected by fragmentation.
Often when you have a backup task that runs on a scheduled basis, there are associated tasks that you would like to perform before or after files are actually copied. CCC offers the option to run shell scripts before and after a backup task, unmount or set the destination as the startup disk, run another CCC backup task, and power management options such as restart and shutdown. If you would like to perform any of these pre or post clone tasks, click the Advanced Settings button below CCC's Source selector.
There are several factors that affect the performance of your backup tasks. Here we describe the most common conditions that affect backup performance, and offer some suggestions for mitigating the effects of those conditions.
Carbon Copy Cloner includes a command line utility that allows you to start, stop, and monitor the progress of specific CCC backup tasks. The utility is located inside of the CCC application bundle. To get basic usage instructions, invoke the utility without arguments in the Terminal application, e.g.: