Level 1

12 points

Partition issue, couldn't unmount disk (error)

Hi,

I have a Mac that I put a partition on a few months ago, I now want to reformat. Yet when I go to my Recovery HD on Lion then to Disk Utility and try to format my HDD it gives me an error saying it couldn't unmount disk, the two partitions on the HDD unmount but the HDD does not. So I googled it and read a few soulitions however the most common one creating a bootable drive with the Recovery HD on it dosen't work either. One of the soulitions I saw was installing Linux on a removable drive and formating the drive from their, however that seems inpractical for what I'm trying to accomplish, if anyone has a fix for this it would be greatly apreactited.

Thanks.

MacBook Pro, Mac OS X (10.7.3)

Posted on Apr 22, 2012 2:59 AM

42 replies

goldish Author

Level 1

12 points

Apr 24, 2012 7:03 AM in response to Linc Davis

I am not trying to partiontion anything, I'm trying to remove a current partition.

"Hi, I have a Mac that I put a partition on a few months ago, I now want to reformat."

goldish Author

Level 1

12 points

Apr 24, 2012 7:05 AM in response to Shootist007

'click the Minus Sign'

I have done that, when I get to this stage it just gives me that error, that it can't unmount the drive.

Linc Davis

Level 10

209,739 points

Apr 24, 2012 7:36 AM in response to goldish

Boot from another device as suggested above.

goldish Author

Level 1

12 points

Apr 27, 2012 2:28 AM in response to Linc Davis

"I googled it and read a few soulitions however the most common one creating a bootable drive with the Recovery HD on it dosen't work either"

tried.

goldish Author

Level 1

12 points

Apr 27, 2012 2:29 AM in response to goldish

does no one have an answer?

Shootist007

Level 6

16,709 points

Apr 27, 2012 3:51 AM in response to goldish

Post a screen shot of the Disk Utility window with the partition tab shown.

Linc Davis

Level 10

209,739 points

Apr 27, 2012 5:27 AM in response to goldish

Describe exactly, step by step, what you did and what happened, including the complete text of any error message you saw.

Linc Davis

Level 10

209,739 points

Apr 29, 2012 7:12 AM in response to goldish

For the second and last time, you can't partition the drive while booted from one of its partitions. You must boot from another physical device.

goldish Author

Level 1

12 points

Apr 29, 2012 8:53 AM in response to Linc Davis

and as I've explained I've download the usb image for the lion recovery HD booted from it and it still does not work

Bishnupb

Level 1

0 points

Jan 20, 2013 1:47 AM in response to Willeyeam

Thanks this method works on my mac recovery.

Aug 13, 2013 1:06 AM in response to geoffist

Thanks geoffist - worked perfectly and exactly solution i was looking for

Cho_420

Level 1

0 points

Feb 18, 2015 9:33 AM in response to geoffist

Thanks geoffist, this worked like a charm.

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Partition issue, couldn't unmount disk (error)