I have a HD partition that is having problems. I have 3 partitions on that drive.

When the partition is mounted (after boot) the disk can not unmount. However in single-user mode the partition is not not mounted. This would be the best time to delete the partition.

What do I need to type to remove the partition in single-user mode?

Note: You can use an example with the names disk0s3 and the name of partition "Install". Also I am using OS X Mavericks.

  • What is the reason for single user mode? Is disk utility in recovery hd not an option? If so, you might state it since it the obvious clear solution that's easiest to implement.
    – bmike
    Oct 28, 2015 at 19:38
  • @bmike The partition is mounted in recovery mode and I said that once it is mounted it doesn't unmount.
    – Racing121
    Oct 28, 2015 at 19:58
  • What error do you get when you issue diskutil reformat disk0s3 while in terminal under recovery? Since disk0s3 is normally your Recovery HD, you might need to provide a diskutil list for someone to help further. Internet recovery will let you wipe everyone - but again, if you have older hardware, that's not an option either.
    – bmike
    Oct 28, 2015 at 21:19
  • @bmike "disk0s3" was an example name. The problem is with a partition I made from Macintosh HD. When I try and format it says it could not format because it could not be unmounted. I think my HD is coming to the stage of replacement so I will think about that.
    – Racing121
    Oct 28, 2015 at 21:40

1 Answer 1


Boot to Recovery HD or internet recovery since the Disk Management Framework isn't loaded in single user mode:

diskutil unmount disk0s3
diskutil reformat disk0s3

If you run into more problems - diskutil verifyDisk and verifyVolume and their repair variants might help to get at the underlying error condition on your volume.

  • 1
    Thank you very much. All works fine now. I will now think about replacing the HD soon
    – Racing121
    Oct 29, 2015 at 9:00

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