Preparing your backup disk for a backup of macOS

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Note: This will erase all data on your backup disk!!!

Launch Disk Utility

Open a Finder window and navigate to Applications > Utilities and double click on Disk Utility.

Launch Disk Utility

The remaining steps vary considerably depending on the operating system you are running. Choose About This Mac from the Apple menu to determine your current OS, then make a selection below.


Instructions for High Sierra

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Show All Devices

Disk Utility in High Sierra offers a very simplified view of your devices by default. Unfortunately, this hides the devices that you need to select to modify the partitioning of your backup disk. Before doing anything else in Disk Utility, choose Show All Devices from the View menu, or from the View popup button in Disk Utility's toolbar.

Select the backup disk

Select the backup disk

Click to select the disk that you would like to use for your backup. This disk should not be the same as your startup disk.

The name of a new disk will often include the manufacturer’s name (e.g. WD My Book 111D Media...). A startup disk will often include the manufacturer's serial number in the title (e.g. TOSHIBA MK50...).

Select the backup disk

Erase the backup disk

Click on the Erase button in Disk Utility's toolbar, then configure the name, format, and partitioning scheme of your backup disk. You can set the name to whatever you like, but set the Scheme to GUID Partition Map.

Choosing a Format for your destination volume

Starting in macOS High Sierra, both APFS and Mac OS Extended (Journaled) are acceptable formats for a backup of macOS 10.13. Mirroring Apple's recommendations, we recommend that you choose APFS if your destination device is a Flash storage-based device (e.g. an SSD) and will be used to back up 10.13 or higher. Choose Mac OS Extended (Journaled) if your destination device is a spinning-platter-based device (i.e. a hard disk drive, or HDD), or if you are backing up an operating system older than 10.13.

When you erase an APFS-formatted startup disk, erase the whole device

If you're erasing an APFS-formatted volume that has (or had) an installation of macOS, it's important to erase the whole container of the volume, not just the volume that you can see. When you use APFS for an installation of macOS, the container will have additional hidden partitions that retain information specific to the previous OS (indicated by the red rectangle on the right in the screenshot below). To remove all of those remnants, select and erase the whole device ("Apple SSD" in the screenshot below) – Disk Utility can't erase the container alone, so erase the whole device.

Select the backup disk

Click the Erase button when you are finished configuring the name, format, and partition scheme for your destination.

Erase the backup disk

Your new hard drive is now ready to accept backups created by Carbon Copy Cloner!


Instructions for El Capitan and Sierra

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Select the backup disk

Click to select the disk that you would like to use for your backup. This disk should not be the same as your startup disk.

The name of a new disk will often include the manufacturer’s name (e.g. WD My Book 111D Media...). A startup disk will often include the manufacturer's serial number in the title (e.g. TOSHIBA MK50...).

Select the backup disk

Erase the backup disk

Click on the Erase button in Disk Utility's toolbar, then configure the name, format, and partitioning scheme of your backup disk. You can set the name to whatever you like, but set the Format to Mac OS Extended (Journaled) and set the Scheme to GUID Partition Map, then click the Erase button.

Erase the backup disk

Don't Use Time Machine

Click Don’t Use. You may use the same backup disk for both Time Machine and CCC backups, but if you do so, you must use a dedicated partition for the Time Machine backup. Otherwise Time Machine will consume all available space on the backup volume and make it impossible for CCC to use the backup volume.

Don't Use Time Machine

Your new hard drive is now ready to accept backups created by Carbon Copy Cloner!


Instructions for Yosemite

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Select the backup disk

Click to select the disk that you would like to use for your backup. This disk should not be the same as your startup disk.

The name of a new disk will often include the storage capacity and manufacturer’s name (e.g. 500.07 GB WD My Passp...). A startup disk will often include the manufacturer's serial number in the title (e.g. 320.07 GB TOSHIBA MK3255GSXF Media).

Select the backup disk

Partition the backup disk

Click on the Partition tab.

Partition the backup disk

Choose 1 Partition from the Partition Layout popup menu (or more if desired).

Click on Options.

Choose GUID Partition Table, then click the OK.

Name the Volume

Name the Volume

Format the Volume

Select Mac OS Extended (Journaled) from the Partition Format popup menu.

Format the Volume

Click Apply.

Ensure that you have selected the correct disk for your backup drive. This step will delete all data from the selected disk. Click Partition.

Now skip ahead to the remainder of the instructions that are not OS-specific.

Related Documentation

"My disk is already formatted HFS+, why am I getting this warning?"
Video: Preparing a drive for a backup of the macOS in macOS 10.11 or higher
Video: Creating a new/additional partition (OS X 10.10 and earlier)
Support for third party filesystems (e.g. NTFS, FAT32)