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.

Right-click the drive and select the Change Drive Letter and Path option.The remaining steps vary considerably depending on the operating system you are running.

Search for Create and format hard disks partitions and click the top result to open Disk Management.

To unmount a drive with Disk Management, use these steps: If you want to unmount a drive, you can also use the same Disk Management, mountvol, and DiskPart tools. If you want to make the drive mountable again, you will need to revert the changes (see above steps). Also, the system will no longer try to mount it automatically.

When you unmount a drive manually, you will remove the mount point making the storage inaccessible. Type the following command to mount the drive on Windows 10 and press Enter: assign letter DRIVE-LETTERIn the command, replace DRIVE-LETTER with the letter you want to mount and access the storage.For example, this command mounts the drive and assigns the e drive letter: assign letter e.Source: Windows Central (Image credit: Source: Windows Central)

Could not unmount disk when formatting