Why can't I erase my hard drive or reformat MBR to GUID?

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MacBook Pro 13" Unibody Early 2011

2011년 상반기 모델, A1278 / 2.3 GHz i5 또는 2.7 GHz i7 프로세서.

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Sarah Green @sarahgreen59348

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게시일: 2015년 8월 22일

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Why can't I erase my hard drive or reformat MBR to GUID?

I'm getting ready to sell my MacBook Pro (Early 2011) and want to erase the hard drive and do a fresh install of Yosemite. I'm currently running 10.8.5 Mountain Lion. I bought the computer used, and do not have the original install disk (should have been Snow Leopard).

The hard drive is currently formatted as MBR, and disk utility won't allow me to access any erase options, create new partitions or select the GUID scheme. I'm also unable to access internet recovery mode when booting with cmd + option + R.

Any ideas on how to at least clear the disk? Even better if I can get it to GUID so that I can install Yosemite.

Thanks!

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I’m trying to format a used disc to start a fresh install of Sierra on a MacBook Pro I’m reviving.

When in the install Mac OS utility I get the error - Disk not formatted in GUID.

I exit to disk Utility and attempt to erase again in GUID - I get an error every time. It will erase in MBR but not GUID.

Any thoughts?

MakeItSimple 의 2020년 7월 24일

What are you using? You need to be formatting the drive under a bootable macOS drive. If you are using anything else it won't prep the drive properly.

Dan 의 2020년 7월 24일

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I’m trying to format a used disc to start a fresh install of Sierra on a MacBook Pro I’m reviving.

When in the install Mac OS utility I get the error - Disk not formatted in GUID.

I exit to disk Utility and attempt to erase again in GUID - I get an error every time. It will erase in MBR but not GUID.

Any thoughts? — MakeItSimple
What are you using? You need to be formatting the drive under a bootable macOS drive. If you are using anything else it won't prep the drive properly. — Dan

Dan @danj 평판: 479.3k Self employed contract worker 35 329 971 · Answer 1 · 2015-08-22T17:07:07-07:00

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Dan @danj

평판: 479.3k

Self employed contract worker

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329

971

게시일: 2015년 8월 22일

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Do you have access to a second Mac? If you do you could try connecting your system to it via FireWire and startup your system in Target mode. At that point your system acts like an external drive. Using the other system will allow you to delete the partition and setup & install a fresh OS install.

OK, While that will allow you to delete the partitions and reformat the drive it won't work for an OS.

Lets try this way:

Get a USB thumb drive (16GB or larger)
Download the OS installer from the App Store, make a backup copy
Then create the GUID partition map on the thumb drive and format the partition with Mac OS Extended (Journaled) with Disk Utility.
Run the OS installer and install the OS onto the thumb drive.
Once done, copy to it the copy of the OS installer.
Restart your system holding down the Option key so you gain access to the boot manager select the thumb drive.
At this point you should be able to reformat the drive using Disk Utility on the thumb drive and using the OS installer on the thumb drive install a fresh copy of the OS.

Do make sure you are connected to the internet as there are some updates your system will need.

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I do have access to a second Mac, but it's a 2007 running Leopard. Will that essentially throw me backwards in terms of my current OS (Mountain Lion) and require me to buy an upgrade from Apple?

Sarah Green 의 2015년 8월 23일

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MacBook Pro 13" Unibody Early 2011

Why can't I erase my hard drive or reformat MBR to GUID?

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Update >> 8/24/15

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