Disk Utility Help Needed.

[ShadowedSight]

Okay guys, I really need some help.
I bought a Macbook Pro with Lion installed. I setup Windows with Bootcamp and ran that for a while. Now, I wanted to clean install JUST Macosx for school in two days. I deleted the Bootcamp partition with Disk Utility, like an idiot. I made a Lion Recovery External Drive and I'm trying to just erase the entire hard drive. Whenever I go to do that though, it says "Unable to unmount." I'm really stuck, and I could use some help. All I want to do is delete everything off this hard drive and start again.

Please help, anyone. And thank you so much!

 

[unixperience]

hey mate, its actually pretty simple..... well unless they changed things with lion... everything that should be simple isn't... but anyway

you typically can't unmount the os, and you can never delete a mounted partition... because you are using it. there are two ways around this, one is to use an osx install cd, then use the disk utility from there, because you are running off the CD, NOT the hd.

If you have a bootable backup, you can also boot from the backup, and use the disk utility again on the internal drive.

 

[gr8tfly]

So you are booted off of an external USB stick with the Lion Recovery HD on it or Lion Installer? You will need to startup using this - not the internal drive.

I'm not sure exactly why you would get the error (unless, as the previous post said, you are booted off the internal drive), but if you want to erase the entire drive, you can set it up with a single new partition. In Disk Utility, select the drive itself (not a partition), then click on the Partiton tab. In the layout menu, select "1 Partition", format "Mac OS Extended (journaled)". Then, click Apply. This will erase all the data on the drive.

Is your USB drive just the Recovery HD partiton, or is it a full install? If the former, you will be downloading Lion, so expect the install to take a bit of time.

I'm not clear on how you recover iLife, but either it will be part of the recovery install, or you will be able to download it from the Mac App Store. I just haven't read of exactly what the procedure for that is.

 

[Quad5Ny]

If you have your reinstall media, then I'm guessing the steps below are what your looking for?

How to Clean Install OS X

Part One: Partitioning the hard drive

1. Insert the Mac OS X Install DVD into the optical drive, or insert the Software Reinstall Drive into the USB port.
   
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2. Turn on or restart the computer.
   
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3. Press and hold the Option key at startup to select the volume containing the installer.
   
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4. If your are using a wireless mouse, a mouse icon should appear asking you to turn the mouse on so that the computer can discover it.
   
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5. Select a language, then press the right arrow key.
   
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6. Click the Utilities menu, the choose Disk Utility.
   
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7. In the box to the left Select your hard drive.
   
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8. Click the Partition tab.
   
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9. Under Volume Scheme choose "1 Partition" (This will Erase the Entire drive, including Boot Camp Partitions)
   
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10. Click the Options button and make sure "GUID Partition Table" is selected.
    
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11. To the right of Format choose "Mac OS Extended (Journaled)".
    
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12. To the right of Name Type "Macintosh HD".
    
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13. Click Apply.
    
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14. After the partition is formatted, choose Quit Disk Utility from the Disk Utility menu.

Part Two: Installing the operating system

1. When the Mac OS X Installer screen appears, click Continue.
   
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2. When the license agreement appears, click Agree.
   
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3. Select the disk you partitioned. It should now be highlighted with a green arrow.
   
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4. Click Install. A status bar appears on the bottom of the screen while Mac OS X installs.
   
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5. An Additional Information screen appears, advising you that you operating system has been installed. Click Continue.
   
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6. An Install Succeeded screen appears. Click Restart.

Original Steps Edited from: http://support.apple.com/kb/ht3910