How to Partition a Drive in OS X El Capitan Using Disk Utility

Disk Utility, a free app included with OS X and macOS, is a multipurpose, easy-to-use tool for working with hard drives, SSDs, and disk images. Among other things, Disk Utility can erase, format, repair, and partition hard drives and SSDs, as well as create RAID arrays.

OS X El Capitan brought a makeover to Disk Utility. While it retained most of its key features, including the ability to partition a drive into multiple volumes, Disk Utility got a new look and changed some processes.

Here's a look at how to partition a hard drive if you're using Disk Utility in an OS X El Capitan system.

While this article focuses on partitioning a hard drive with Disk Utility in OS X El Capitan, the process is similar in macOS Catalina, Mojave, High Sierra, and Sierra.

About Partitioning a Hard Drive

Partitioning a disk divides it into individual sections, each of which acts as a separate volume. It's possible to partition most types of storage devices, including SSDs, hard drives, and USB flash drives.

In our example, we're going to add one partition to a hard drive. This same process can create any number of partitions, depending on your needs.

As a precaution, make sure you back up data on your Mac hard drive before creating new partitions on your device.

How to Partition a Hard Drive in OS X El Capitan

If the drive that you wish to partition is an external drive, be sure it's connected to your Mac and powered on.

  1. From the Applications folder, launch Disk Utility. Or, type Disk Utility into Spotlight Search.

  2. Select the drive you want to partition from the sidebar on the left. 

    Internal storage devices appear below the Internal section in the sidebar. External devices appear below the External section in the sidebar. You can only partition the drive, not any of the associated volumes.

    Selecting disk to partition
  3. The selected drive will appear in the right-hand pane with details about it, such as location, how it's connected, and the partition map in use.

    Screenshot of Disk Utility in El Capitan
  4. Select the Partition button. You'll see a pie chart of how the drive is currently divided.

    Disk Utility > Partition
  5. To add another volume, click the plus (+) button just below the pie chart.

    Adding a volume
  6. Type a name for the volume in the Partition field.

    Naming the partition
  7. Select the Format dropdown menu, then choose a file system format.

    Partition format

    OS X Extended (Journaled) is usually the default. It's the most commonly used file system on El Capitan Macs.

  8. Enter the size or drag the resize control to increase or decrease the size of the volume.

    Setting the partition size
  9. Select Apply.

    Screenshot of adding a partition with Disk Utility in El Capitan
  10. When you see Operation Successful, select Done.

    Screenshot of creating a partition with Disk Utility in El Capitan
  11. You'll see your new partition listed in your Disk Utility sidebar.

    Screenshot of adding partition with Disk Utility in El Capitan
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