Using OS X's Disk Utility

Disk Utility Does It All

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Disk Utility, a free application included with the Mac, is a multipurpose, easy-to-use tool for working with hard drives and drive images. Among other things, Disk Utility can erase, format, repair, and partition hard drives, as well as create RAID arrays. You can also use it to create a clone of any drive, including your startup drive.

Disk Utility always had a few changes made to it with each release of the Mac OS, but when Apple released OS X El Capitan, Disk Utility received a major makeover. Because of the extent of the changes to Disk Utility, we're presenting guides for both Macs using OS X Yosemite and earlier, and those using OS X El Capitan and later.

The first five items below cover using Disk Utility with OS X El Capitan and later, while the rest cover using Disk Utility with OS X Yosemite and earlier.

Disk Utility's First Aid
First Aid completed with no issues as shown by the green checkmark. Screen shot courtesy of Coyote Moon, Inc.

 Disk Utility's ability to repair disk issues underwent an overhaul with OS X El Capitan. The new Disk Utility app's First Aid feature can verify and repair drives connected to your Mac, but if your troubles are with the startup drive, you'll have to take a few extra steps.

Learn the ins and outs of Disk Utility First Aid in OS X El Capitan and later… More »

Disk Utility OS X El Capitan
Screen shot courtesy of Coyote Moon, Inc.

 The version of Disk Utility that's included with OS X El Capitan and later versions of the Mac OS has been panned for removing capabilities and changing how certain features work.

When it comes to formatting a drive connected to your Mac, the basics remain the same; even so, check out this in-depth guide to get the latest on formatting your drive… More »

Disk Utility Partition Pie Chart El Capitan
Screen shot courtesy of Coyote Moon, Inc.

Partitioning a drive into multiple volumes is still taken care of by Disk Utility, but there have been changes, including the use of a pie chart to visualize how a drive's partition table is divided up.

All in all, it’s a useful visual, though a bit different than the stacked column chart used in earlier versions of Disk Utility.

If you're ready to divide a drive into multiple volumes, dive in and take a look… More »

Disk Utility Partitioning OS X El Capitan
Screen shot courtesy of Coyote Moon, Inc.

Resizing a volume without losing data is still possible using Disk Utility, however, the process has undergone quite a few changes that can leave many users scratching their heads.

If you need to enlarge or shrink a volume without losing data, be sure to read the rules to resizing… More »

Disk Utility Restore process details in OS X El Capitan
Screen shot courtesy of Coyote Moon, Inc.

Disk Utility has always had the capability to copy an entire disk and create a clone of the target volume. Disk Utility calls this process a Restore, and while the feature is still present, it too has undergone quite a few changes.

If you need to create a clone of your Mac’s drive, be sure to take a look at this guide first… More »

Format a drive with Disk Utility
Screen shot courtesy of Coyote Moon, Inc.

Disk Utility’s main purpose is to erase and format a Mac’s hard drives. In this guide, you will learn how to erase a disk, how to choose different erase options to meet any security need, how to format a drive, including how to zero out data and test the drive during formatting, and finally, how to format or erase a startup drive. More »

Partitioning a disk with Disk Utility
Screen shot courtesy of Coyote Moon, Inc.

Disk Utility does more than just format a hard drive. You can also use Disk Utility to partition a drive into multiple volumes. Find out how with this guide. You will also learn the difference between hard drives, volumes, and partitions. More »

Using Disk Utility to resize a volume
Screen shot courtesy of Coyote Moon, Inc.

The version of Disk Utility bundled with OS X 10.5 has a few notable new features, specifically, the ability to add, delete, and resize hard drive partitions without first erasing the hard drive. If you need a slightly larger partition, or you would like to split a partition into multiple partitions, you can do it with Disk Utility, without losing the data that’s currently stored on the drive.

Resizing volumes or adding new partitions with Disk Utility is fairly straightforward, but you need be aware of the limitations of both options.

In this guide, we’ll look at resizing an existing volume, as well as creating and deleting partitions, in many cases without losing existing data. More »

Disk Utility First Aid
Screen shot courtesy of Coyote Moon, Inc.

Disk Utility has the ability to repair many common problems that can cause your drive to perform poorly or exhibit errors. Disk Utility can also repair file and folder permission issues that the system may be experiencing. Repairing permissions is a safe undertaking and is often part of routine maintenance for your Mac. More »

Use Disk Utility to Clone a drive.
Screen shot courtesy of Coyote Moon, Inc.

You have probably heard the admonition to back up your startup disk before performing any system updates. That's an excellent idea, and something I recommend often, but you may wonder just how to go about it.

The answer is: Any way you want, as long as you get it done. This guide will show you how to use Disk Utility to perform the backup. Disk Utility has two features that make it a good candidate for backing up a startup disk. First, it can produce a backup that is bootable, so you can use it as a startup disk in an emergency. And second, it's free. You already have it, because it's included with OS X. More »

Using Disk Utility to create a RAID 0 (Striped) set
Screen shot courtesy of Coyote Moon, Inc.

RAID 0, also know as striped, is one of the many RAID levels supported by OS X and Disk Utility. RAID 0 lets you assign two or more disks as a striped set. Once you create the striped set, your Mac will see it as a single disk drive. But when your Mac writes data to the RAID 0 striped set, the data will be distributed across all of the drives that make up the set. Because each disk has less to do, it takes less time to write the data. The same is true when reading data; instead of a single disk having to seek out and then send a large block of data, multiple disks each stream their part of the data stream. As a result, RAID 0 striped sets can provide a dynamic increase in disk performance, resulting in faster OS X performance on your Mac. More »

Creating a RAID 1 (Mirrored) set with Disk Utility
Screen shot courtesy of Coyote Moon, Inc.

RAID 1, also known as a mirror or mirroring, is one of the many RAID levels supported by OS X and Disk Utility. RAID 1 lets you assign two or more disks as a mirrored set. Once you create the mirrored set, your Mac will see it as a single disk drive. But when your Mac writes data to the mirrored set, it will duplicate the data across all members of the set. This ensures that your data is protected against loss if any hard drive in the RAID 1 set fails. In fact, as long as any single member of the set remains functional, your Mac will continue to operate normally, and provide complete access to your data. More »

Creating a JBOD (concatenated) RAID set with Disk Utility
Screen shot courtesy of Coyote Moon, Inc.

A JBOD RAID set or array, also known as a concatenated or spanning RAID, is one of the many RAID levels supported by OS X and Disk Utility.

JBOD allows you to create a large virtual disk drive by concatenating two or more smaller drives together. The individual hard drives that make up a JBOD RAID can be of different sizes and manufacturers. The total size of the JBOD RAID is the combined total of all the individual drives in the set. More »