Manually re-partition a drive from Terminal

Owned by Seth Garrepy
Last updated: Jan 30, 2017
2 min read

Follow this guide if you attempt to image a computer and you receive the following notification:

Step-by-step guide

To re-partition the system disk, boot the system in NetBoot or off of a tech drive before following the below steps:

  1. Open /Application/Utilities/Terminal.app
  2. We need to determine if the computer has a two internal disks ("Fusion drive") or a single internal disk (HDD/SSD). Type the following command:
    diskutil list | grep "internal"
    Make note of the "disk" identifier(s) in the output, since we'll use that later.
  3. If you see only one disk listed in the output, proceed to Step 4. If you see two disks listed in the output, proceed to Step 5.
  4. To re-partition a single disk, enter the below two commands, replacing "disk#" with the identifier from Step 2:
    diskutil partitionDisk disk# jhfs+ "Macintosh HD" 100%
    diskutil cs convert disk#s2
    1. Proceed to Step 6.

  5. To re-partition a Fusion drive, enter the below commands, replacing "disk#" with the identifiers from Step 2.

    1. On the first disk run: 
      diskutil partitionDisk disk# jhfs+ temp 100%
    2. On the second disk run: 
      diskutil partitionDisk disk# jhfs+ temp2 100%
    3. Join the two partitions together and enable CoreStorage, replacing BOTH "disk#" with each of the identifiers from Step 2:
      diskutil cs create "Internal Disk" disk#s2 disk#s2
    4. Format the new volume:
      diskutil cs createVolume "Internal Disk" jhfs+ "Macintosh HD" 100%
    5. Proceed to Step 6.
  6. Still in Terminal, type the following command to verify that conversion was successful:
         diskutil info disk#s2
    1. Look at the field labeled "Partition Type". If it says "Apple_CoreStorage", then the procedure was completed successfully. Look at the graphic below for an example of a correctly-made CoreStorage LVG.
  7. You may now quit Terminal and proceed with imaging the computer as typical.