Checking Drive Health in OS X from Terminal

checking drive health from terminal

All Mac owners should know how to check drive health in OS X using Terminal. While it may seem intimidating if you’re not used to the command line, it’s super easy to do once you actually try it – we’ll help you!

Most importantly, there are significant benefits to performing these simple “checkups” once every couple of weeks. The small learning curve is worth it.

In this article, we’ll go through these benefits in more detail and we’ll show you 2 easy ways to check your Mac’s drive health using the Terminal app. Read on!

Why It is Vital to Check Drive Health in MacOS

As we previously mentioned, there are significant benefits to periodically checking your Mac’s drive health. They can save you time, money, and a lot of frustration. Specifically:

  • Prevent data loss: Keep your data safe by knowing your drive’s health status so you can avoid getting blindsided by errors and sudden failures, which may directly or indirectly lead to data loss.
  • Optimize performance: Maintain your drive’s performance by addressing issues like bad sectors and file system errors, which can cause slowdowns and errors.
  • Prevent unexpected failures: Avoid sudden drive failures (which can further damage said drive) by identifying issues before they get worse.
  • Maximize warranty: For new drives, quickly identify issues that resulted in DOA (“Dead on Arrival”) and qualify for refund or replacement.
  • Plan backups: Determine when drive failure is imminent so you can create an updated backup of your data in advance or transfer it to a new drive.
  • Proactively maintain drive: Prolong your drive’s health and identify potential problems before they happen or get worse.

How to Check Mac Hard Drive Health Using Terminal

In this section, we’ll demonstrate 2 simple methods to check your Mac’s hard drive health using Terminal. The first method uses the native Mac tool Disk Utility to check for file system issues and other disk-related errors.

The second method uses a third-party tool that provides a much more comprehensive analysis of your drive. It not only identifies issues but also provides error codes that can tell you what caused the malfunction.

The methods below can also be used to check M1 Mac SSD health (and newer models).

Method 1: Using Diskutil

The first tool we’ll cover is Disk Utility, which already comes with macOS so you won’t have to install anything. There are 2 commands you can use:

  • verifyDisk Scans your entire disk. Use this command to get a comprehensive report of your entire drive’s overall health.
  • verifyVolume Scans a specific volume. Use this command to focus on a single volume, isolate issues, and save time.

There are scenarios where one or the other is preferable. But if it’s your first time doing it, we suggest using verifyDisk to get a thorough analysis.

The verifyDisk command can also fix corrupted hard drives by repairing any errors it can along the way.

To check your hard drive’s health with Diskutil:

Step 1: Open the Terminal app (Finder > Applications > Utilities).
Terminal App in Utilities

Step 2: Type the following command and hit Return:
diskutil list
Identify your disk’s IDENTIFIER
type command diskutil list, note your disk's indentifier, hit return

Step 3: Then, type the following command and hit Return:
diskutil verifyDisk /dev/disk0
Replace “disk0” with your own disk’s identifier.

Once you execute the verifyDisk command in step 3, the Terminal app will generate a succinct report that will notify you if it encountered any problems or not.

Method 2: Using Smartmontools

The next tool we’ll demonstrate is called Smartmontools. It’s another command line-based utility that can perform a comprehensive scan of your drive – both on the hardware and software level. It will then generate a report with a number of helpful parameters.

These parameters will give you a good idea of what may be wrong with your drive and whether you need to secure your data ASAP. We’ll briefly discuss the most important parameters after the guide.

If you prefer, you can also download GSmartControl, which is an open-source GUI (graphical user interface) for Smartmontools.

To check your Mac drive’s health using Smartmontools:

Step 1: Open the Terminal app (Finder > Applications Utilities).
Terminal App in Utilities

Step 2: If you already installed Homebrew, skip to step 3. If not, type the following command and hit Return:
/bin/bash -c “$(curl -fsSL”

Step 3: Once Homebrew is installed, type the following command and hit Return:
brew install smartmontools
type command brew install smarmontools and hit return

Step 4: Type the following command and hit Return:
diskutil list
Note your disk’s IDENTIFIER.
type command diskutil list, note your disk's indentifier, hit return

Step 5: Type the following command and hit Return:
smartctl -a /dev/disk0
type command smrtctl-a/dev/disk0, hot return

You can also use the man smartctl command to learn more about the utility and its functionality.

Once you execute the command in step 5, Smartmontools will scan your drive and generate a health report. Here are some parameters to watch out for:

SMART overall-health self-assessment test result– PASSED and FAILED attributes that indicate your drive’s current health status.

Critical Warning– Pending critical issues that need attention. 0x00 indicates no critical problems.

Temperature, Warning Comp. Temperature, Critical Comp. Temperature– Current drive temperature and instances of potential overheating.

Unsafe Shutdowns– The number of times your Mac had shut down unexpectedly.

Media and Data Integrity Errors– Number of instances where data was lost due to errors (including Unsafe Shutdowns).

Error Information Log Entries, Error Information– Number of error reports (log entries) and error indicators.

If any of these parameters look odd or alarming, see Smartmontools’ Help Page for more information on what to do and who you can ask for technical support.

How to Recover Data From Failing Drive

If your drive is on the brink of death but you can still access it, copy or back up your data to another location ASAP. But if it’s already in a state where you can’t perform read-and-write operations anymore, we recommend using data recovery software to extract your data directly from the drive, bypassing Finder.

For this article, we recommend Disk Drill specifically. Not only does it have a nice GUI and powerful recovery capabilities, but it also has 2 useful tools for this scenario that are missing from many other apps:

(1) Byte-to-byte backup, which allows you to create an image backup (essentially an exact copy of your entire drive compressed into an image file), which you can scan with its recovery tool. This gives you a much better chance of successful recovery. And (2) S.M.A.R.T. (Self-Monitoring, Analysis, and Reporting Technology), which gives you real-time reports on your drive health.

To recover data from a failing drive using data recovery software:

Step 1: Connect a reliable external drive to your Mac, ensuring it has enough space for your drive’s backup image and the recovered data.

Step 2: Download and install Disk Drill (we recommend installing it to the external drive you connected in step 1 by dragging its icon to the drive’s icon instead of to your Applications folder when prompted).

Step 3: Launch Disk Drill and click Byte-to-byte backup in the left sidebar. Then, select your Mac drive and click Create backup.
create backup in byte-to-byte back up in Disk drill

Step 4: Name your image backup and choose a location on your external drive where Disk Drill will save the image. Then, click Save.
Attach selected image created in disk drill

Step 5: Once Disk Drill has created the image, click the Home button.

Step 6: Click Storage Devices in the left sidebar. Then, click Attach disk image… in the bottom of the window.

Step 7: Select the image you created in steps 3-4 and click Attach.
Attach selected image created in disk drill

Step 8: Select the image backup you attached in step 6 and click Search for lost data. Once the scan is done, click Review found items.
Search for lost data, then review found items in Disk drill

Step 9: From this window, you can browse, search, and preview your files. But you should secure your data ASAP so mark the box at the top of the leftmost column to select everything. Then, click Recover.
Recover after file preview, tap recover button

Step 10: Choose a location on the external drive you connected in step 1 as the save destination. Then, click OK to proceed with recovery.
click next to save destination

Disk Drill Basic for Mac does not offer free data recovery. However, you can preview all of your files as much as you want. You can also scan your drive and create backups for free. So you can figure out which data is recoverable and create a backup image without purchasing the app.


Knowing how to check your Mac’s drive health in Terminal is an important skill that can help you prolong your device’s lifespan, keep your Mac running optimally, and keep your data safe!

Just keep in mind that all storage devices have a finite lifespan, no matter how careful you are. The best you can do is maximize it. When you know it’s on the way out, create a backup (we recommend using Time Machine) ASAP or move your data to a new device.


To know if your external hard drive is corrupted on Mac, use the verifyDisk command in the Terminal app or install smartmontools. Both methods will scan your drive and generate reports on various parameters related to your drive’s health and performance.
To run Disk Utility from Terminal, use the diskutil command. You’ll have to use it in conjunction with other commands – such as diskutil list (shows all disks, volumes, and partitions) and diskutil verifyDisk (scans your drive for errors).
The Mac equivalent of chkdsk is verifyDisk. verifyDisk scans your drive for errors and will try to repair what it can along the way.
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Alejandro Santos
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Alejandro is Macgasm’s Chief Writer and Apple ecosystem enthusiast. He pens the majority of troubleshooting guides and software reviews for this website, tapping into his love for technology and extensive background in technical writing. He started his career by helping… Full Bio