While trying to get Boot Camp set up on my MacBook Pro 15 inch Retina 2015 it asked me to partition my hard drive. Doing so I partitioned my 1 TB hard drive so that it dedicated 750 gb to mac and 250 gb to Boot Camp. However the Boot Camp set up was not successful and now my Mac's hard drive is only 750 GB big. With Boot Camp uninstalled it is still 750 GB. The 250 GB can not be added again on my Mac. Every time I try and add a partition to the "unallocated space" it does not work. I can't get my hard drive back to the full 1 tb. It looks something like this.

enter image description here.

Someone please help me restore my Mac to its 1 TB hard drive. It would be very much appreciated.

  • Is FileVault (encryption) enabled? If not, please see this post for reverting from a CoreStorage logical volume group: Unable to Resize Partitions
    – Redarm
    May 24 '15 at 0:29

OS X Yosemite automatically converts hard drives to Core Storage volumes, whose sizes can't be changed. You need to undo the Core Storage conversion.

Here are instructions for making that happen. (source - this method worked for me). This method should be non-destructive, but as always, take a backup first!

  1. Boot into Recovery HD. If for any reason you don't have Recovery HD, then you'll have to make a bootable Yosemite drive and boot into that.

  2. In the Menu Bar, select Utilities > Terminal.

  3. Run diskutil cs list. You'll get an output that looks like this (credits to the Ask Different user in my source):

  1. Select your Logical Volume ID (the one highlighted in the screenshot) and copy it to the clipboard.

  2. Run the Terminal command diskutil cs revert Paste-Your-Logical-Volume-ID-Here.

  3. Run diskutil cs list to verify that your computer can't find any CS volumes.

  4. You're done! Now Disk Utility should be able to resize your HD!


Here is how I was able to resolve this issue.

  1. Create another partition of your Mac's HD (Something really small 6 GB). Not the Macintosh HD portion, but the entire drive itself. By creating this new partition, it should also show this unallocated space as a new (Untitled) partition.

    enter image description here

  2. Go back to your main drive and repartition it to 1 partition. Remove the one you created earlier and the Untitled one). After you make this change, it should add all of your hard drive's space to the you Macintosh HD assuming you do not have anymore partitions that you would like to keep.

Let me know if you have any questions I can help you with.

  • Anyone know what data exists in that remainder? Is it solely the recovery app? Just wondering if System Integrity (SIP) exposed access and whether it could be corrupt. Messing with eGPU scripts from github and trying to completely sanitize it.
    – neaumusic
    Sep 13 '18 at 21:42

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