📑 Table of Contents

  1. Opening Disk Utility
  2. Running First Aid
  3. APFS vs HFS+: Understanding File Systems
  4. Checking Disk Health
  5. Creating and Managing Partitions
  6. Erasing and Reformatting Drives
  7. Terminal: diskutil Commands
  8. Built-in vs Third-Party Disk Tools

Disk Utility is one of the most powerful yet underappreciated tools built into macOS. This professional-grade utility handles everything from routine disk health checks to full drive erasure, partition management, and RAID configuration. Whether you need to repair a misbehaving drive, prepare a new external disk, or diagnose storage issues, Disk Utility has you covered without needing any third-party software.

In this guide, we will cover every major feature of Disk Utility, explain the critical differences between Apple's modern APFS file system and the legacy HFS+, and provide terminal commands for advanced disk management that goes beyond what the graphical interface offers.

🍏 Apple Insider

Disk Utility was completely redesigned in OS X El Capitan (2015) with a simplified interface. While some advanced features were initially removed, Apple has been steadily adding them back. The current version in macOS Ventura and later is the most capable yet.

Opening Disk Utility

💡 Pro Tip

To see all disks, containers, and volumes, go to View → Show All Devices in Disk Utility. The default view hides physical disks and APFS containers, showing only volumes.

Running First Aid

First Aid verifies your disk's file system structure and repairs errors it finds. It checks directory structures, catalog files, extent overflow files, and multi-linked files.

How to Run First Aid

  1. Open Disk Utility and select the volume or disk you want to check in the sidebar.
  2. Click the "First Aid" button in the toolbar.
  3. Click "Run" to begin the verification and repair process.
  4. Wait for the process to complete. This can take several minutes on large drives.

First Aid results will show one of these outcomes:

💡 Did You Know?

Running First Aid on your startup disk while booted from it has limitations. For thorough startup disk repairs, boot into Recovery Mode (Cmd+R on Intel, hold Power on Apple Silicon) and run Disk Utility from there.

APFS vs HFS+: Understanding File Systems

macOS supports two primary file systems, and understanding their differences is essential for making the right formatting choices:

FeatureAPFS (Apple File System)HFS+ (Mac OS Extended)
IntroducedmacOS High Sierra (2017)Mac OS 8.1 (1998)
Optimized forSSDs and flash storageHard drives (HDDs)
EncryptionNative, hardware-acceleratedFileVault (software layer)
Snapshots✅ Native support❌ Not supported
Space sharing✅ Containers share free space❌ Fixed partitions
Clones✅ Instant file clones❌ Full copies only
Crash protection✅ Copy-on-write✅ Journaling
Best forInternal SSDs, modern MacsExternal HDDs, legacy support
💡 Pro Tip

All modern Macs should use APFS for internal drives. Use HFS+ (Mac OS Extended, Journaled) only for external hard drives that need compatibility with older Macs or Time Machine backups on HDDs.

Checking Disk Health

Beyond First Aid, you can check your disk's SMART (Self-Monitoring, Analysis, and Reporting Technology) status:

  1. Open Disk Utility and select the physical disk (not volume) in the sidebar.
  2. Look at the bottom of the window for "S.M.A.R.T. Status".
  3. "Verified" means the drive reports no hardware issues.
  4. "Failing" means the drive has detected hardware problems. Back up immediately and replace the drive.

Note: SMART status is only available for internal drives and directly connected external drives. It does not work through USB hubs or RAID enclosures in many cases.

Creating and Managing Partitions

Partitioning divides a single physical disk into multiple independent volumes. With APFS, Apple introduced a better alternative called "APFS Volumes" that share free space within a container.

Adding an APFS Volume (Recommended)

  1. Select an existing APFS volume in Disk Utility.
  2. Click the "+" button in the toolbar (or Edit → Add APFS Volume).
  3. Name the volume and choose a format (APFS, APFS Encrypted, etc.).
  4. Optionally set size quotas (reserve or limit).
  5. Click "Add".

APFS volumes within the same container share free space dynamically, unlike traditional partitions which have fixed sizes.

Erasing and Reformatting Drives

To completely erase a drive (external drives, USB sticks, or preparing to sell a Mac):

  1. Select the drive in Disk Utility.
  2. Click "Erase" in the toolbar.
  3. Choose a name, format (APFS for SSDs, Mac OS Extended for HDDs), and scheme (GUID Partition Map for Macs).
  4. Click "Erase" to begin.
⚠️ Warning

Erasing a drive permanently deletes all data on it. Ensure you have backups before erasing. For drives you are selling or giving away, choose "Erase" with security options to prevent data recovery.

Terminal: diskutil Commands

List all disks and volumes

Terminal — List Disks
diskutil list

Get detailed info about a specific disk

Terminal — Disk Info
diskutil info disk0

Verify a volume

Terminal — Verify Volume
diskutil verifyVolume /

Repair a volume

Terminal — Repair Volume
diskutil repairVolume /Volumes/MyDrive

Erase a disk (CAUTION)

Terminal — Erase Disk
diskutil eraseDisk APFS "MyDisk" GPT disk2
⚠️ Warning

The diskutil eraseDisk command immediately and irreversibly erases the specified disk. Triple-check the disk identifier (disk0, disk1, disk2, etc.) before running this command.

Built-in vs Third-Party Disk Tools

FeatureDisk UtilityThird-Party Tools
First Aid / repair✅ Full support✅ Sometimes deeper analysis
SMART monitoring✅ Basic status✅ Detailed SMART attributes
Partition management✅ APFS volumes + partitions✅ More visualization options
Data recovery❌ Not included✅ Major selling point
Secure erase✅ Built-in options✅ Additional algorithms
CostFree$20–$100+

Disk Utility handles routine disk management excellently. Third-party tools are primarily valuable for data recovery and detailed SMART health monitoring with predictive failure analysis.