Why Partition Option Grayed Out in Mac and How to Resolve It

MacBook Computer Repair

Partitioning a disk on a Mac is useful for organizing data, but external hard drives and USB keys are often formatted for Windows, causing issues with Mac’s file system when using Disk Utility.

Hard drive partitioning is a common topic discussed in many tech forums. In a thread on Apple’s support forum, users have expressed difficulties when their Mac Disk Utility partition option becomes grayed out while they try to partition their external hard drives.

Perhaps, you’ve just bought a new external hard drive and are eager to use it on your Mac. But somehow, you cannot access the Mac Disk Utility partition, so you can’t write data to the drive.

Fear not, we have a solution to this problem. In this post, we will guide you through a step-by-step process on how to restore a grayed-out Disk Utility partition. Many Apple users who have faced Partition grayed out in Mac issues eventually partitioned their external hard drives with the help of these fixes.

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Why Partition Grayed Out in Mac (Plus Solution)

Problem 1: Sometimes, you cannot access the Mac Disk Utility partition because your hard drive doesn’t have sufficient space.

Solution: If you want to go ahead with the partitioning task, you need to create more space on your hard drive. In other words, you have to erase the data on your drive to create additional space. You can then format your hard drive using GUID Partition Table. After that, go ahead with your partitioning plans.

Important Note: Before formatting your hard drive, back up your most important files. Needless to say, the process will get rid of all the data on the disk, so you risk losing your files for good.

Problem 2: As mentioned earlier, external drives are usually not compatible with macOS, which may bring issues when you want to partition. In most cases, users choose the wrong partitioning option, and as a result, the Partition option in Disk Utility remains grayed out.

Solution: The right way you should follow when selecting a partition option is to choose the drive name within the list provided under Internal or External (depending on the device you want to partition). Your hard drive will be available on the left side of the Disk Utility pane.

How to Restore Grayed Out Disk Utility Partition: Format Your Hard Drive to Work with Mac

To format your external disk to be compatible with macOS, connect your hard drive to the Mac and follow these steps:

  1. Open Disk Utility by going to Applications, then select Utilities > Disk Utility.
  2. Choose the drive name within the list provided under ‘External’. If your hard drive is connected, it will show in the left panel of the Disk Utility. Highlight the disk and click the Erase button in the top toolbar.
  3. Wait for a window asking you to select the file system you want to use to format your external drive to pop up. For your case, you will select ‘Mac OS Extended (Journaled). But if you have plans to use your disk for both PC and Mac, then a better option is ‘ExFAT’. You can also rename your hard disk here to your desired name.
  4. Wait for the formatting process to complete. The process usually takes less than a minute, but it depends on the size of your hard disk.
  5. When done, confirm if the formatting was successful by right-clicking the icon for your disk on the desktop and then choosing Get Info. The information is available under Format.

If it reads “Mac OS Extended (Journaled)”, congratulations, you successfully restored the grayed-out Disk Utility and your hard disk is now compatible with macOS.

Partitioning Your Hard Drive on Mac

Now that you have prepared your hard drive to work with Mac, the next step is to partition it on your Mac by following these steps:

  1. Launch the Disk Utility app on your Mac and highlight the hard drive icon under ‘External’ (for external hard drives). If you choose any other drive, the partition option will become unclickable.
  2. Now click Partition on the top toolbar. A window that has partition information will pop up. On the left side of the window, look for the name and the volume size of your hard drive. The next step is to click add (+) button on the bottom of the window to create partitions on your disk. Allocate the desired volume size to each partition.
  3. Hit the Apply button and wait for a window asking you to verify your choices. Confirm the changes by clicking the Partition button.
  4. Wait for the process to complete. You can confirm if the process was successful on your desktop. You will see additional disk icons show

Pro Tip: If the main reason for partitioning your hard drive is to install Windows, Apple recommends that you use Boot Camp Assistant instead of Disk Utility. You should, however, note that you cannot use Disk Utility to erase a partition generated using Boot Camp Assistant.

What Else Can You Do to Resolve Common Mac Issues

If you’re like many users, you may have encountered other challenges on your Mac besides hard drive partitioning. Mac users have also reported slow performance, random freezes, and space issues. The best way to guarantee the best performance for your Mac is to scan and clean the computer.

Maintaining your Mac at peak performance often requires regular housekeeping tasks, such as cleaning up junk files, deleting unnecessary apps, and addressing other elements that may take up space. Software tools like Mac repair app can aid you in these tasks. Be sure to research and choose the tool that best fits your requirements. Remember, alternatives to this software are available.

We hope the above solutions helped you to restore the grayed-out Disk Utility partition. As always, we would love to hear your success story. Share it in the comment section. Also, let us know if you experienced challenges during the partitioning process.

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Shari Peterson
3 years ago

I still have Partition grayed out despite erasing and checking that it is Mac OS Extended (Journaled). I am trying to create a Flash drive (Untitled) to install El Capitan on an old computer that has no OS currently installed. I am using another computer to create this flash install drive because I can’t get out of OS X Utility on the computer I am trying to install the OS on. I am stuck. How do I partition when it is grayed out?

Terry McDanel
2 years ago

Solution: “The right way you should follow when selecting a partition option is to choose the drive name within the list provided under Internal or External (depending on the device you want to partition).”

This sentence is completely incomprehensible English to me. What is he trying to say??

ric rose
2 years ago

Unfortunately, this does not work. I used Disk Utility on a WD SSD external drive. I erased it and formatted it with EXFAT. When done the SSD still has 76.4MB of used space and cannot be partitioned.

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