Partition failed with error, Couldn't unmount disk

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admench Author

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Partition failed with error, Couldn't unmount disk

Please can anybody help me

I'm running a new 12 core Mac Pro. 2 x 2.66 gHz, 8GB ram.

Lion v 10.7.2

I want to Partition the drive that came with the mac into 3.

I have tried the following:

Simply restarting holding the Option key, selecting Disk Utility, choosing my hard drive, going to Partition and setting up my choice of 200, 200, 600 as 3 partitions. Hitting apply. I get the error "Partition failed with error, Couldn't unmount disk"
Restarting using lion Recovery Disk Assistant, doing the same as point 1, same error message.
Both of the above methods, but manually unmounting the Macintosh HD before setting up the partitions and applying. Same error message.
Restarting using the Recovery HD. same error message.

Posted on Nov 28, 2011 9:28 AM

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Answer 1

Tony T1

Level 6

10,232 points

Nov 28, 2011 10:09 AM in response to admench

When in Recovery HD, did you try a [Repair] on the HD?

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Answer 2

admench Author

Level 1

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Nov 28, 2011 10:15 AM in response to Tony T1

I just tried a repair. Status: disk was ok.

Re-tried the partition. No joy. Any extra more specific tips that you can offer?

Thanks

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Answer 3

Tony T1

Level 6

10,232 points

Nov 28, 2011 10:26 AM in response to admench

Did you only try partitioning in Recovery HD?

If so, try it with a normal boot.

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Answer 4

admench Author

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Nov 28, 2011 11:26 AM in response to Tony T1

Thanks for your continued help Tony. Do you mean normal boot into the regular operating system setting i.e. no keys held down in bootup? I think I have tried this, with the same result.

I am away from the computer in question currently, so I will try this to make sure it is a possible solution in 12 hours when I return to it.

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Answer 5

Tony T1

Level 6

10,232 points

Nov 28, 2011 1:42 PM in response to admench

admench wrote:

Thanks for your continued help Tony. Do you mean normal boot into the regular operating system setting i.e. no keys held down in bootup? I think I have tried this, with the same result.

Yes, that's what I meant. If that doesn't work, verify that you have a G.U.I.D. partition scheme (you probably do):

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Answer 6

admench Author

Level 1

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Dec 1, 2011 3:32 AM in response to Tony T1

Hi Tony

After only trying it in all restore modes, ie Restore HD and Lion USB Restore it now worked in regular boot.

Thanks for your help.

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