Operating System

Using Disk Utility for OS X

The disk utility for Mac OS X is very powerful. It allows for the control of storage drives attached to the computer. For example, the main internal hard drive can have permissions repaired, or the drive can be partitioned to allow for another operating system to be installed on the computer.

This is located in Applications > Utilities > Disk Utility.

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Disk Utility has some very useful features. On the left are drives are mountable images. The picture to the right has this computer’s hard drive, named “Macintosh HD”, and a bootable image named “Mac Installer.dmg”.

The most important section is the area with the hard drive. This area has a list of volumes currently connected to the computer, such as the internal hard drive or usb devices.

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Volumes can be unmounted from the computer (read: unusable to the user and not visible in Finder) to allow for First Aid on a drive and for partitioning the drive into parts. Note: These actions cannot be performed on Macintosh HD because I am not currently an administrator.

The volume can also be verified, the system can run a check to make sure that data is in its correct state. If at some point it is not in the correct state, Disk Utility will tell the user what to do, which usually involves running repair disk. This is a very powerful function as it allows the user to run checks and repair the computer without reinstalling the operating system.

Screen Shot 2016-10-08 at 1.37.58 PMUsually, nested inside of each volume is at least one partition. In the case of the image above, the volume “Macintosh HD” also has a partition with the same name. Partitions can also be verified, as well as have their disk permissions verified.

Disk permissions can change because of applications installing incorrectly or a failing drive. Checking if these have changed or the general state of these permissions is very important to IT professionals. Between the ability to check permissions and verifying the disk, it is possible to tell if a disk needs to be replaced, wiped and re-imaged, or is doing fine.Screen Shot 2016-10-08 at 1.39.55 PM

In the above menus, there are the options for encrypting drives, for journaling, and in other versions of Mac it can manage RAID. There is the option, for partitions, to open in Finder, if the partition is mounted.


Screen Shot 2016-10-08 at 1.41.30 PMLastly, there is a nice console that shows the history of what has happened to the drive. It also shows the result and the suggested further actions for the drive, like sometimes Mac will suggest to reboot into recovery to fix the drive.

Disk Utility differs from Windows computers, computers that often need to have the operating system at least partially reinstalled, rather than just repaired. Windows even goes so far as to make this easy for users to access.

In all, the Mac Disk Utility is a very useful application. The user can check the condition of their drive and potentially fix it, without needing a reinstall or a replacement.