If you're using an application firewall such as Little Snitch, you will see several outgoing network connections coming from CCC. We explain below what connections you should expect to see, and also explain why some connections that look unexpected are simply misreported by Little Snitch.
CCC will make external network connections for the following activity:
In addition to backing up to volumes formatted with the macOS standard HFS+ or APFS format (collectively referred to as "macOS-formatted" from here forward), CCC can copy user data files to network volumes (e.g. AFP and SMB via macOS and Windows File Sharing) and to other non-macOS-formatted volumes such as FAT32 or ExFAT. Non-macOS-formatted volumes are presented in CCC's Source and Destination selectors in the same manner as macOS-formatted volumes, so there are no special steps required for backing up to or from these filesystems.
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 postflight tasks, click the Advanced Settings button at the bottom of CCC's main window.
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.
CCC offers the option of securely copying your selected data to another Macintosh on your network (or anywhere on the Internet for that matter) via the Remote Macintosh... options in the Source and Destination selectors. After a brief setup procedure to establish trust between your Mac and the destination Mac, simply choose the source or destination volume/folder on the remote Mac and CCC will take care of the rest.
Before setting up CCC to back up to a remote Macintosh, you must:
Rather than requiring you to enter admin credentials every time you want to run a task or make changes to a task, CCC only requires users with administrative privileges to authenticate once when CCC is initially installed. While this configuration is easier to use, there are situations where this configuration is not appropriate. If you leave your system unattended with an admin user logged in, someone with physical access to your system can modify or run your CCC backup tasks.
CCC maintains a list of certain files and folders that are automatically excluded from a backup task. The contents of this list were determined based on Apple recommendations and years of experience. The following is a list of the items that are excluded along with an explanation of why they are excluded.
If you frequently use virtual machine container files (e.g. with Parallels, VMWare, VirtualBox, etc.), you may find that CCC's SafetyNet folder tends to get very large, very quickly, or that snapshots on the destination consume space very quickly. Every time you open your virtual machine, the monolithic virtual machine container file is modified, and CCC will require that it gets backed up during the next backup task. If the SafetyNet is on, CCC will move the older version of the VM container file into the SafetyNet folder (or it will be retained by a snapshot on the destination).
You can access the contents of a disk image the same way that you access other volumes and external hard drives on macOS. Double-click on the disk image file to mount its filesystem, then navigate the filesystem in the Finder to access individual files and folders. If you have the permission to access the files that you would like to restore, simply drag those items to the volume that you would like to restore them to.
Restoring individual items or an entire disk image to another hard drive using CCC
To restore files or an entire filesystem from a disk image: