Since the OS X El Capitan released, the Disk Utility, which comes bundled with any operating system, has changed significantly. The new application received a lightweight design, but on the other hand, the performance of some functions became unclear. Many are faced with a problem when trying to combine multiple logical drives into one.

Anyway, you can use Disk Utility on a Mac to manage internal disks and external storage devices.

Disk Utility

  • Monitor your data and manage it by splitting the disk into several parts, called partitions. In the Finder, each properly formatted partition is displayed as a volume;
  • Create a disk image – a single file with which files can be moved between computers, create backup copies and archive their work;
  • Check for errors on disks and volumes and fix them. If there are several volumes on the device and one of them is almost full, you can enlarge it without losing any data;
  • Reduced variation of working with RAID-arrays.

When a storage device is partitioned, it is divided into separate sections, which are listed in the “Devices” section of the Finder side menu as separate volumes. You may need to partition the disk if you want to install multiple operating systems or change the formatting of the device.

You can easily create new partitions on a device that has at least one volume containing data if there is free space on it and resize them too.

WARNING!!! It is recommended that you back up your data before creating new partitions on the device.

Resize Volume

If there are several volumes on the device and one of them is almost full, you can enlarge it without losing any data.

Increase Size

To increase a volume, you must delete the volume that is on the device after it, and then move the end point of the volume you want to increase to the free space. The last volume of the device cannot be expanded.

WARNING!!! When you delete a volume, all the data in it is erased. Before performing this operation, be sure to back up your data.

  • In the side menu, select the device that contains the volume you want to increase, then click the “Partition” button;
How to Resize Partition on a Mac?
  • In the disk diagram on the left, select the volume you want to delete, then click the “-” button at the bottom, then click “Apply”;
How to Resize Partition on a Mac?
  • The volume is deleted, reformatting is performed, and all free space is assigned to the previous volume;
How to Resize Partition on a Mac?
  • Click “Done”.
How to Resize Partition on a Mac?

Decrease Size

To decrease the size of the volume is about the same as described above:

  • In the disk utility where the section disk diagram is shown, holding the “Cmnd” button and you should reduce the size of the volume to an acceptable value.
How to Resize Partition on a Mac?


Working with partitions is quite complicated and insecure. Often unknowingly, you can delete the necessary data. Therefore, I advise you not to rush and carry out all actions carefully. Ideally, to start working on a live system, it is worthwhile to train in a virtual system.

It’s the best time to ask questions and give us your feedback in comments.


Hi there! My Name is Vincent Lago! My goal is to share insightful reviews, guides, and manuals for people looking to know more about current solutions for Apple hardware and OS. I have years of technological background knowledge including owning a custom iMacs & PCs which was using for different types of business. And now, I want to share my experience with you.

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