Updating boot support partitions for the volume as
If the Unable to Unmount Error is triggered by first aid or formatting a non-boot partition, you may be able to fix the error by booting from the Recovery partition that is included with all new versions of OS X.
This will Again, if the disk throwing the errors is the same as the primary boot partition that Recovery is also on, the above method may not work to resolve the problem.
The journal for device will then be moved externally onto the newly created Apple_Journal partition. internal hard disks), consideration of ownership settings on FSOs is the default. When ownership is disabled, Owner and Group ID settings on FSOs appear to the user and programs as the current user and group instead of their actual on-disk settings.Erasing freespace on a volume will leave it exactly as it was from an end-user perspective, with the exception that it will not be possible to recover deleted files or data using utility software.If you need to erase all contents of a partition but not its hosting whole-disk, use the zero Disk or random Disk verbs.This will allow you to fix the problem, regardless of the cause, by one of two means, the first is a sure-thing to fix the issue, while the other only works sometimes. This is the recommended method because it should always fix the error.You will need any OS X boot drive to complete this task, I used a Mavericks boot installer drive for this purpose but others should work too, whether they are installation drives or just recovery drives, the important thing is they are bootable and separate from the primary boot disk that stores the installed OS: I ran into this twice recently, first when attempting to modify partitions on a drive, which came right along with a separate “partition failed” error, and again was triggered when attempting to format those partitions.