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I've just bought a new MacBook Pro with Mac OS X Lion.

The problem started when I tried to divide the hard disk into more than 3 partitions, so I erased the existing partition and tried to divide the hard disk using Disk Utility. So, I opened the "Partition" tab and chose "3 partitions" and when I hit "Apply" it says that "Couldn't unmount partition".

Can anyone please tell me how to fix that or how can I partition my hard disk?

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I'm not trying to unmount the volume. All I'm trying to do is to partition the hard disk & this error appears. I just need a simple way that can divide my hard disk into 3 partitions. –  Muhammad Reda Apr 3 '12 at 1:38

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ALERT: THIS WILL ERASE YOUR DATA WHEN YOU PARTITION. PLEASE BE SURE THAT ALL IMPORTANT INFORMATION IS BACKED UP VIA TIME MACHINE OR OTHER METHODS!

Load OS X Lion from a USB Flash Drive or DVD from your post screen by holding option on your MacBook Pro's startup. Open Disk Utility from there, and repartition your hard drive to your desired specifications. Remember: this will erase your data (files and programs), and all of your data will need to be reloaded.

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Actually, DiskUtility can now resize and repartition non-destructively, in some cases. –  Alex Apr 3 '12 at 1:48
    
The data already erased :) and the system starts to this window i.stack.imgur.com/r4mzu.png Can u plz tell me in details how can I partition the hard disk? it's my first mac ever. –  Muhammad Reda Apr 3 '12 at 1:48
    
Muhammad - if you get that, choose Disk Utility and partition it as you were before. You'll then want to either Rstore from Time Machine, or reinstall OSX to get your system running again. –  Alex Apr 3 '12 at 2:03
    
@Alex while this may be true, this method is always effective, and will give Muhammad what he needs. –  lrussell810 Apr 3 '12 at 2:05
    
@Alex, the problem is that, when I try to use disk utility to partition the hard disk and hit "Apply" I get this error "Couldn't unmount disk" –  Muhammad Reda Apr 3 '12 at 2:14

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