

You should also see the name of the disk such as ‘Macintosh HD’. It will look like ‘diskx’ where ‘x’ is an integer starting at 0. From the listing, look in the Identifier column for your disk identifier.
#Force unmount disk mac terminal full
(Or if you are booting to your own bootable drive with a full system, open Disk Utility from /Applications/Utilities). You can try booting from OS X Recovery (by holding ‘CMD’ + ‘R’ keys at startup) or an external drive and use the command line to attempt to unmount or erase the disk:ġ) Once booted from OS X Recovery, select Terminal from the Utilities pull down menu. (For example to Erase/Partition the disk).

If you have created your own bootable drive with a full system, open Disk Utility from /Applications/Utilities. If you have used our method above to create a bootable installer, choose ‘Disk Utility’ from the available menu.

Then select the desired external drive from the startup manager screen and press the enter key.
#Force unmount disk mac terminal install
To create your own bootable disk, refer to our blog ‘Creating a Mavericks bootable install disk’. You can then run Disk Utility from there.Īn external drive or a network drive is preferred if it is the internal hard drive you have an issue with, since the OS X Recovery is a partition on the same physical drive which may not be able to successfully unmount or modify your internal disk. So the first thing to do is to startup the Mac from another bootable drive such as an external drive or OS X Recovery. Normally, any ‘Couldn’t Unmount Disk’ error is attributed to circumstances where the boot drive is being modified or is being used by an application or process. I have found myself recently experiencing a couple of Macs which would not allow me to repair the directory or permissions in Disk Utility, or erase/partition the drive with an error such as: ‘Disc erase failed couldn’t unmount disc’ or ‘Disk Erase failed with the error: Couldn’t unmount disk.’Įven trying to use Network Deployment tools such as Apple’s Netinstall service or DeployStudio have also failed to deploy due to these errors.
