Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I was trying to create a new partition on my macbook by booting through Recovery USB using the disk Utility. But I am unable to create a partition since it throws a "Cannot unmount disk" error. I tried to manually unmount the drive but it doesn't work.

share|improve this question
You can't unmount it because the Recovery Partition HD is on that drive. – user3463 Sep 20 '11 at 5:40
up vote 0 down vote accepted

Try Erasing the the existing partition first. If the drive has been claimed by CoreStorage, you won't be allowed to change the partitions until it's clean.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.