I've recently bought a macbook pro with 512gb ssd that are divided into 2 drives:Two drives

These two partitions are both formatted as OS X Extended Journaled:

1: Drive one

2: Drive two

When i try to merge them into a single volume i always get this error: Error

Please help me solve this problem. Thank you !

  • 1
    It is giving you that error because it is unable to unmount or eject MAC on disk1, which is the current volume being used by the operating system. Your best bet is to create a bootable USB with GParted on it. Boot to GParted and make the changes to your hard drive from there. – n8te Sep 10 '16 at 10:54
  • @n8te - Seems a bit pointless, as the Mac has a built-in Recovery Partition you can use to do the same task. – Tetsujin Sep 11 '16 at 7:22
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    @Tetsujin - Fair enough. And you're right. I've just been using GParted for as long as I can remember so it's just a personal preference. But obviously it would be easier for OP to use the built-in utility, so +1 for your answer below. – n8te Sep 11 '16 at 7:47

As with all tasks of this type, having a current backup is highly recommended.
This method should preserve all existing data, but better safe than sorry.

The simplest way to 'merge' those volumes is actually to delete the second & then enlarge the first to take up the newly freed space. Any data you need from the second should be copied to the first before starting.

You can do this by rebooting & holding Cmd ⌘ R at the boot chimes.
This will bring you to Recovery mode, where you can access Disk Utility.

  • Select the Drive itself, rather than any of the volumes & then click Partition at the top.
  • A new pane will open showing the drive as a pie chart, with the partitions showing on a 'clock face' style display staring at 12:00 & running clockwise. That will make your first partition the one on the right, going from 12:00 to 6:00 on the 'clock face' & the second partition from 6:00 round to 12:00.
  • Select the second partition & click the [-] minus button underneath, then click Apply.
  • After confirmation & the process is completed, you can then click the first partition & use the handles at the edge of the pie-slice to enlarge it up to the full size. Again click Apply & confirm.
  • Once complete you can then reboot the machine & use your new full-size partition.

More comprehensive guide at AboutTech : Disk Utility: How to Resize a Mac Volume (OS X El Capitan or Later)

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