because Spotlight prevents the unmount request). Unmount any volumes on the specified diskĭisk Utility occasionally has problems with unmounting a volume while attempting to erase it (e.g. If your disk is a Fusion device, you may erase the 'container' within it instead. You must select the whole disk to correctly initialize the device. Please pay particular attention to selecting the disk, not one of the volumes on the disk. A startup disk will often include the manufacturer's serial number in the title (e.g. The name of a new disk will often include the manufacturer’s name (e.g. This disk should not be the same as your startup 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.Ĭlick to select the disk that you would like to use as the destination for your CCC task. Unfortunately, this hides the devices that you need to select to modify the partitioning of your backup disk. Watch a video of this tutorial on YouTube Show All Devicesĭisk Utility offers a very simplified view of your devices by default. Instructions for Big Sur, Catalina, Mojave, and High Sierra

macOS 10.12 Sierra and OS X 10.11 El Capitan.

macOS 11Big Sur, 10.15 Catalina, 10.14 Mojave, and 10.13 High Sierra.Choose About This Mac from the Apple menu to determine your current OS, then make a selection below. The remaining steps vary considerably depending on the operating system you are running.

Partition external drive on mac