Resolve External Hard Drive Not Mounting on Mac

When you connect an external hard drive on a Mac, it shows up in the following locations – Desktop, Finder, and Disk Utility. But sometimes, it doesn’t appear anywhere on your system.

An external hard drive that does not show up or mount on a Mac can make the data on it inaccessible. Luckily, there are ways to resolve this issue and make an external drive accessible on Mac.

This post will discuss the methods available to resolve the external hard drive not mounting on Mac issue. But first, let’s find out more about this problem and its causes.

Why an External Hard Drive Not Showing Up/Mounting on Mac?

Whether it’s a Toshiba, Seagate, WD, or any other brand’s external drive, if it doesn’t show up anywhere on your Mac, it could be due to several common reasons –

• USB connectivity issues
• Not setting preferences in macOS
• Partition map damage
• Device incompatibility
• Physical damage on the drive

Methods to Fix the External Hard Drive Not Mounting on Mac Issue

Many users get confused between an external hard drive not mounting on Mac and external hard drive not showing up. There is a fine distinction between the two –

When an external hard drive is showing up only in the Disk Utility and is grayed out, it is not mounting. But if the connected external hard drive is not showing up anywhere on a Mac, then you won’t be able to access it at all.

If you notice your external hard drive not showing up or grayed out on the desktop, use the methods below to fix any underlying issues –

Pre-Activity

Before moving to the advanced methods, try updating your macOS. Running outdated macOS can sometimes cause numerous system issues and glitches. If you cannot mount an external hard drive on a Mac, it could be due to an unresolved bug or outdated drivers related to storage drives. A macOS update can easily fix such issues.

Method 1: Change macOS Finder Settings

Sometimes, when you connect an external hard drive to your Mac, it shows up in the Disk Utility but not anywhere else. This may happen due to specific settings in the Finder Preferences, where you did not select to show external disks on the Desktop and in Finder. The steps to fix this are quite simple –

• Open Finder from the Dock. From the top Menu Bar, go to Finder > Preferences.
• In the Finder Preferences window, click the General tab.
• Under the Show these items on the Desktop section, select the External disks checkbox. Your desktop will now show the external hard drive icon.
• Click the Sidebar tab. Under the Locations section, select the External disks checkbox. Your Finder sidebar will now show the external hard drive.

You should also toggle the external hard disk visibility in the Disk Utility’s View menu. Ensure that the “Show All Devices” option is selected.

• Press Command + Space Bar to open Spotlight.
• Type disk utility and hit Return to open Disk Utility.
• Click the View menu located at the top-left corner of Disk Utility and select Show All Devices. Your Disk Utility’s sidebar will now show the external hard drive.

Method 2: Reset Mac Firmware Settings

If the connected external hard drive is not mounting on Mac, you may try to reset NVRAM & PRAM, and SMC on your Mac.

To Reset NVRAM (Non-volatile RAM) & PRAM (Parameter RAM)

• Restart Mac, then immediately press and hold the Option + command + P + R keys until you hear a second chime.

To Reset SMC (System Management Controller) Reset

• For an iMac, Mac Pro/mini, or laptop with a removable battery—detach the power cable or take out the battery, then press and hold the Power button for 5 seconds.
• For MacBook Air, MacBook Pro, or MacBook with a non-removable battery—press and hold Shift + Control + Option + Power Button for 10 seconds.

Method 3: Fix External Hard Drive Connectivity Issue

An external hard drive may not show up on your Mac due to connectivity issues. You can resolve such connectivity issues by trying these simple troubleshooting tips –

• Reconnect the USB connector or adapter to fit the hard drive snugly.
• Connect the hard drive to a different USB port or a different Mac.
• Replace the USB cable or adapter if you suspect it to be damaged.
• Connect an external power source if the hard drive requires one.
• Check the LED light to ensure the storage device is powered on and working.

Method 4: Troubleshoot External Hard Drive with Disk Utility

Sometimes, when you connect an external hard drive to your Mac, it appears grayed out on the desktop and other locations, possibly due to some logical errors. You can troubleshoot such disk-related issues via First Aid in Disk Utility. Here’s what to do –

Mount the external hard drive from Disk Utility.

• Open Disk Utility, then select the grayed-out hard drive from the sidebar.
• Click the Mount tab. The drive will mount automatically.

Repair the hard drive from Disk Utility.

• Open Disk Utility, then select the hard drive from the sidebar.
• Click First Aid, then hit Run to verify and repair logical issues with the hard drive.

Note – After repairing the problematic external hard drive via First Aid, if it unmounts intermittently or shows error messages, check its S.M.A.R.T. status from the Disk Utility. If you find a possibility of imminent drive failure, you can clone the drive on a new, healthy hard drive.

Method 5: Mount External HDD via Terminal Using the ‘diskutil list’ Command

You can also use the Terminal to mount the external HDD on your Mac. To do that –

• Launch Terminal via Spotlight.
• Type the command diskutil list into the Terminal command window. It will display each disk that is connected to your Mac. The next step is to locate the identifier for the required drive.

• Once you have located the required disk, mount the hard disk by entering the following command: diskutil mount/dev/disk0.

Note – Replace disk0 with the identifier of the external hard drive you want to mount.

Method 6: Recover Data from Non-Mounting External Mac Hard Drive

If none of the above methods helped you mount your drive on Mac, it is time for you to use a professional Mac data recovery software to recover any critical data from the hard drive. Connect the external drive and ensure that it is at least showing in Disk Utility. Now, follow the steps below –

• On your Mac, download and install Stellar Data Recovery Professional for Mac.
• Launch the software by double-clicking on its icon.
• Select the type of files present on the drive, click Next.
• Select the non-mounting external hard drive, then toggle on Deep Scan.
• Click Scan. Let the scan finish.

• Preview the scanned items in Classic, File, or Deleted List. Once a view mode is selected, navigate the folders and preview any scanned files from the right pane.
• Select all the required files by clicking their corresponding checkbox, then click Recover. Specify a save destination, then click Save.

Here is a video tutorial –

Conclusion

We hope the methods mentioned above helped you fix issues preventing your external hard drive from mounting on Mac. In rare cases, you may find an incompatible file system causing the problem. Take a backup of the data on your external hard drive and then format it with APFS or any other Mac-compatible file system.

Tell us in the comments which method worked for you.

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About The Author

Vishal

Vishal is a data recovery expert @Stellar. He addresses data loss scenarios on a Mac. He intends to help people solve their macOS problems. Besides, Vishal prefers to read about astronomy and autobiography, and his favorite is Steve Jobs - The man who thought different written by Karen Bluementhal.