What does this button do?

Avoid mistakes when using Apple’s Disk Utility.

Many people are a little apprehensive when it comes to using any of the applications in their Utilities Folder. Most are pretty harmless, though probably a little cryptic. Open the Console application and you can quickly be overwhelmed with the stream of text floating by. And what is the ColorSync Utility even for?

However, you will probably need to use Disk Utility from time to time. If your hard drive starts developing problems, or if you need to format a new disk, Disk Utility is the tool to use. Disk Utility has five (or six) buttons along the top of the window. Here are the basics concerning what each one does (and doesn’t do),

First Aid

If your drive is having problems. This is the button to use. Select the drive to ‘treat’ and click First Aid. A sheet will drop asking whether you want to run First Aid or cancel. There’s not much damage you can do with this button, but be aware that not all problems can be fixed. If a drive cannot be repaired, it will need to be reformatted, but we’ll get to that later.

Partition

This is the button to use if you want to segment a hard drive into sections that are treated like separate drives, called partitions. Select the drive you want to partition, and click the Partition button. (In older versions of macOS, you will need to click the icon representing the whole drive.) You’ll be presented with a sheet that shows your drive presented as a pie chart. Click the plus button to add a partition, configure the size and format, and then click Apply. A new partition will be added non-destructively to the disk. Just be sure you don’t inadvertently remove any partitions containing any data that’s important to you.

Erase

This button can pretty easily get you into trouble if you’re not careful. Once a drive is erased, it can be difficult or impossible to retrieve any data, so use this button with care, and make sure you have a backup.

When you get a new drive, more often than not, it will be formatted for Windows, so it’s usually a good idea to format (erase) it before you put it to use. With a new drive, make sure you have selected the icon representing the whole drive when clicking the Erase button. This will give you an additional option when erasing the disk. You’ll always be given the option to choose the format. (You should choose Mac OS Extended (Journaled) for rotational drives, and APFS for solid state drives.) When the whole disk is selected, you will also be able to choose the (Partition) Scheme. It is important to set the scheme to GUID Partition Map to maximize Mac compatibility.

Restore

This button went missing when Disk Utility was refreshed in Mac OS X 10.11, but made its return midway through macOS 10.12. The Restore button is used to restore all data from one disk to another. It can either restore data from another disk, or from a disk image file. Beware when using this button, however, because the disk you restore TO will be erased in the process.

Mount/Unmount

A partition is said to be mounted when it is accessible to the computer, and unmounted when it is connected but not accessible. Most disks will mount automatically when connected, and you will most often unmount a disk by dragging it to the trash to eject it or by clicking the eject button next to its icon in a Finder window. However, this functionality is available in Disk Utility as well.

Info

This button is perhaps the most obvious, if least used. Click on the Info button to get more information about a drive. Some of the information will be useful, like capacity and used space, but other information will be cryptic to most.

So there’s Disk Utility in a nutshell. There are of course more things that it can do, but we’ll save those for another article.

As always, we hope you find these tips useful.