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Reformatting Hard Drive, help please (without recovery disk)

Sparky2012

Sparky2012

macrumors 6502
Original poster
Jul 16, 2012
486
279
United Kingdom
So I have done this before on my iMac but I am trying to help my sister do it as she is having several issues with her Macbook Pro 2011.

What you do is you hold Cmd + R until the Apple Logo appears. Then click Disk Utility and then on the left, click the Macintosh HD Volume and click Erase, name the volume and the format OS X Extended (Journaled), and finally hit Erase. Wait a while for it to erase and then back out of Disk Utility and then click on Reinstall OS X and again wait a while.

The part I'm having trouble with is when my sister goes into Disk Utility to erase the Macintosh HD volume, its greyed out and I have no idea why or how to fix it. Help would be much appreciated!
13633490_1044143565641257_122230064_o.jpg
 
While you are in that same recovery screen open Terminal app from the Utilities menu and run each of the commands below then post the results back here so we can take a look. These commands will show the volume layout of the disk.

Code: 
diskutil list

diskutil cs list
 
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Sparky2012 said:
Sorry for the delay. Heres the results:
Click to expand...

Okay... it is not letting you remove that volume because it is encrypted with FileVault. Do this... back in that same recovery screen go back to Terminal and enter the command below. That will wipe the encrypted volume, then you can go back to Disk Utility and in the erase tab format the entire disk like you mentioned earlier.

Code: 
diskutil cs delete "Macintosh HD"

Make sure you do the command exactly like this including the quotes.

Edit: Fixed command typo.
 
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Weaselboy said:
Okay... it is not letting you remove that volume because it is encrypted with FileVault. Do this... back in that same recovery screen go back to Terminal and enter the command below. That will wipe the encrypted volume, then you can go back to Disk Utility and in the erase tab format the entire disk like you mentioned earlier.

Code: 
diskutill cs delete "Macintosh HD"

Make sure you do the command exactly like this including the quotes.
Click to expand...

Sorry for sounding paranoid but the part of the command you gave me "diskutill" is that meant to have 2 l's as other commands you gave me only had one l ?
 
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Sparky2012 said:
No problem. I asked my sister to attempt to turn FileVault off and so might not have to do any of this terminal stuff. I'll keep you posted.
Click to expand...
If you don't want any data on there, it is much much faster to just run this command from recovery. It will clear off that volume in about five seconds. It may take hours to unencrypt the FV volume.
 
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Weaselboy said:
If you don't want any data on there, it is much much faster to just run this command from recovery. It will clear off that volume in about five seconds. It may take hours to unencrypt the FV volume.
Click to expand...

DAMMMNNN, oh well its gonna take about 6 hours apparently... wish I had read your post first haha. Cheers, I'll keep you updated.
 
Just an update. The decryption finished and as you said, we could then wipe the Macintosh HD volume. We did so and reinstalled OS X after backing out of Disk Utility. Everything went smoothly and the MacBook Pro is running well again. Cheers for your help again!
 
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