Forced Unmount of Disk Failure

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Level 1

9 points

Forced Unmount of Disk Failure

Hi Guys,

I'm having some serious issues with rebuilding my MacBook Air 13. I previously had it in a bootcamp configuration, with half the disk for Windows and the other half for Mac OS X, I went and removed the bootcamp partition from the bootcamp utility, this failed so I used disk utility to remove it in an effort to put my Macintosh HD back to the full 128GB available on the SSD. When I couldn't expand the partition, I decided to do a time machine backup and then rebuild by removing all partitions. But when I went to clear out the partitions using the recovery disk utility, it said partition error, couldn't unmount partition. So I dived into the terminal program and decided to use the diskutil unmountDisk /dev/disk0 which is the disk I'm trying to unmounts to partition/format etc. the result is the same as when I use the disktuil unmountDisk force /dev/disk0 and that is "Forced unmounts of disk0 failed: at least one volume could not be unmounted"

I'm at my wits end with this one and any help wiping out the partitioning and rebuilding OS X is really appreciated.

I have no problem with erasing the disk if it were possible from where I am at the moment,

Posted on Sep 23, 2015 2:52 PM

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Answer 1

Eric Root

Level 10

685,483 points

Sep 24, 2015 3:29 PM in response to MattPanton

Do a backup, preferable 2 separate ones on 2 drives. Boot to the Recovery Volume (command - R on a restart or hold down the option/alt key during a restart and select Recovery Volume). Run Disk Utility Verify/Repair Disk and Repair Permissions until you get no errors. Reformat the drive using Disk Utility/Erase Mac OS Extended (Journaled), then click the Option button and select GUID. Then re-install the OS.

OS X Recovery

OS X Recovery (2)

When you reboot, use Setup Assistant to restore your data.

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Answer 2

MattPanton Author

Level 1

9 points

Sep 24, 2015 4:06 PM in response to Eric Root

Hello, thank you for replying, I tried what you've suggested already and it hasn't helped, what did help was booting to a Linux based live cd and then using gparted to delete the partitions that wouldn't unmount it did this easily, rebooted and then went into recovery and restored from a time machine backup which thankfully for,attend the disk to use 100% of available space on the SSD and not the 70GB partition it was in before this fiasco

thanks

Matt

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