8 Fixes to Solve External Hard Drive not Mounting on Mac (Force Mount Ways Usable)

Imagine that one day when you intend to access data on your external hard drive or transfer data from it to another device, you plug the drive into your Mac, but find it not automatically  showing up on Desktop, Finder or Disk Utility. Seriously, your Mac is likely to be unable to mount the external hard drive.

Mounting is a process by which a computer’s operating system makes files and directories on a storage device available for users via the computer’s file system. Your drive is unmountable so that Mac can’t recognize it. Take it easy. This post will guide you on how to fix external hard disk not mounting on Mac with no fuss, also covering how to recover data from unmounted external hard drive before fixing in case of data loss.

How to Force Mount External Hard Disk on Mac?

If you have checked the connection to be fine and also have rebooted your Mac, but your Mac still fails to mount the external hard drive, it indicates that there are other factors resulting in the unmounting issue. Before digging out the reason to repair the unmounted disk, firstly you are suggested to try to force mount it on your Mac for sake of efficiency. 2 tips on how to force mount external hard disk on Mac will be laid as follows.

Method 1: Force external hard drive to mount on Mac by Disk Utility

Disk Utility contains a “Mount” option that can be used to manually force mount an external hard drive. But this method is feasible only when your unmounted drive appears in Disk Utility. Once it suits your occasion, see below for how to force mount external hard disk on Mac.

1. Go to Finder > select Applications folder > find and open Utilities > click Disk Utility.
2. Choose the external volume from sidebar > select “Mount” tab at the top center. After the mounting process finishes, your drive will show up on desktop or Finder.

Method 2: Force mount external hard disk on Mac with Terminal

If Disk Utility Mount not working, several specific Terminal command lines are capable of removing files which blocks your external hard drive from mounting normally. While the pity is that Terminal doesn’t work for undetected disks in all cases. Anyway, you can have a try through following the instruction in details.

1. Connect your drive with the Mac.
2. Launch Terminal by using Spotlight Search.
3. Type the command line: diskutil list > press Enter.
4. You can view the list of all devices. Find out the external disk not mounting. Here the macOS’s internal representation of the disk is “disk1”. 
5. Type the command line: sudo mkdir /Volume/usb. Repalce “usb” with the name of your disk that will not mount. Enter admin password if required to execute this command.
6. Continue to type: sudo mount -t hfs /dev/disk1 /Volumes/usb into the window and execute it. Please note that “disk1” is just an example here. You should also replace the number with your own disk when operating.
7. Check to see if the disk is now mounted on Mac desktop or in the Finder.

How to Recover Data from Unmountable External Hard Drive on Mac?

What if the 2 solutions introduced above both fail to force mount your external hard disk on Mac? Then you have to explore how to repair this disk. However, data loss tends to happen during the disk repairing process, so it’s wise to extract and back up data from the unmounted hard drive before you fix or remount it.

A professional third-party data recovery software is generally the most trustworthy option to restore data from an external hard drive not mounting on Mac. Among masses of competitors on the market, Cisdem Data Recovery tops the list with its high recovery rate and intuitive interface. This program is also a powerful helper in extracting and backing up data from the unmounted hard drive before you fix or remount it, in order to prevent loss of data.

This is the step-by-step guide on using Cisdem Data Recovery to access data inside an unmountable external hard drive.

1. Download, install and launch this software on your Mac.
   ​Free Download
2. Scan the unmounted external hard drive.
   Make sure the external drive is plugged into Mac correctly. Go to Disk Data Recovery mode. The software will detect and display the external hard drive on the right panel. Select it and click “Search for lost files” to initiate drive scanning.
3. Preview the drive data.
   After both quick scan and deep scan done, all recoverable files will be showed based on different file types. Locate your wanted files or tick “Select all” box if you want to recover all the data.
4. Recover data from the external hard drive.
   Select the files and click “Recover” button to retrieve them to a safe location.

How to Fix External Hard Drive not Mounting on Mac Issue?

After rescuing the important files inside the disk not mounted, proceed to fix it with safety. This part will separately deliver 6 ways to fix an external hard drive not mounting on Mac.

Way 1: Relaunch Finder

Restarting Finder is an attempt easy to carry out when your drive doesn’t appear on Finder or desktop. Here’s the guide.

1. Go to the Mac desktop > press Command + Option (Alt) + Escape simultaneously. Force Quit Applications window will pop up.
2. Choose Finder > click “Relaunch” button.
3. Select “Relaunch” to confirm the restarting.

Way 2: Check macOS drive display settings

This is another easy fix also involving Mac Finder. At times your external hard drive could not be mounted smoothly because its display on desktop or Finder has been disabled yet. Let’s see the steps below to solve it.

1. Open Finder from the dock. 
2. Click Finder on the Apple menu bar > select Preference from the drop-down menu.
3. Choose General tab > tick the box next to “External disks”.
4. Next click Sidebar tab > tick the box beside “External disks” under Devices section.

Way 3: Update macOS operating system

Your Mac running too old version will not support the file system of external hard disk, thus disabling Mac to mount an disk appropriately. We say macOS Sierra or earlier can’t be compatible with APFS file system. So try to upgrade your Mac machine with steps here.

1. On Mac desktop, go to Apple menu > About This Mac.
2. Choose Software Update button from the pop-up window.
3. Once there’re any updates available for your computer, hit on Restart to start the upgrade.

Way 4: Perform First Aid in Disk Utility

An external hard drive with internal errors can also make it inaccessible to your Mac. One handy storage device repair feature called First Aid can be used to fix an unmounted hard drive on Mac machine. This feature can check the drive for errors and then repair it if necessary. The following is how to access First Aid.

1. Search for Disk Utility using Spotlight > press Enter to launch it.
2. Select your external hard drive from the list of storage devices on the left sidebar.
3. Click First Aid from the top tool menu.
4. Click “Run” button to initiate the repairing.

Once the fixing process done, eject your external hard drive in a safe manner and reboot your Mac. Then reconnect the drive with Mac to see whether Mac can mount it properly.

Way 5: Reset Mac firmware settings

Firmware invloves the function of your Mac and other hardwares. An external hard disk not mounted might be caused by improper firmware settings as well. This is how to do the resetting. Don’t forget to unplug the external disk from your Mac previously.

How to reset SMC?

For a desktop Mac:

1. Disconnect the power cable of Mac.
2. Re-plug the cable after around 15 seconds.
3. Press Power button 5 seconds later to reboot the Mac.

For a laptop Mac:

1. Disconnect the power cable and Mac, then reconnect them.
2. Press and hold Control+Shift+Option keys & Power button simultaneously for about 10 seconds.
3. Release the above mentioned keys and button.
4. Restart the Mac.

How to reset NVRAM/PRAM?

1. Shut down your Mac.
2. Restart it while holding Command + Option + P + R.
3. Release them when hearing a second startup chime or Apple logo appears and disappears again.

Lastly reconnect the disk when getting to Mac desktop to check if it can be mounted normally.

Way 6: Reformat the unmountable external hard drive

Unreadable file system belongs to one common reason leading to external hard drive not showing up on Mac. This can be resolved via changing the drive format to make it supported by your Mac. It is also a Mac solution without other platforms. Just learn the tutorial as below.

1. Open Disk Utility (detailed step as per Way 4).
2. Go for the drive on the left sidebar under “External” > click “Erase” from the top toolbar.
3. A dialog box will pop up. Select a format for your drive. “Mac OS Extended (Journaled)” is recommended. Also give the drive a name. Then click “Erase” button to start reformatting.
4. When the message “Erase process is complete” comes out, click “Done” to complete the reformat. From now on the external hard drive is assigned with a new file system compatible with your Mac. Thus it can be mounted again.

Wait. What if the external hard drive not mounting on Mac issue can’t be fixed after you try out all the 6 solutions above? Well, it means the drive has been truly corrupted. So is there still any possibility to rescue the important files inside the drive? A beacon of help does exist. Keep reading.

Why is My External Hard Drive not Showing up on Mac? 

To gain a deeper understanding of the issue, you’d better know the major reasons why external hard disk can’t be properly mounted on Mac. Here as they are grouped:

• Poor connectivity. 
  Foreign matters like dust may stay on the USB connectors and ports between your external hard drive and Mac, resulting in a dirty and loose connection, which hinders your drive from being detected by Mac.
• Disabled display settings.
  External hard disk connected to your Mac can be just hidden rather than unmounted because of your wrong settings. The drive will show up again if you simply enable the display settings on Mac.
• Incompatible file system of the storage device. 
  It is possible that the file system format of your external hard dive is not supported by Mac, so Mac can’t recognize it successfully. This is one reason that people usually ignore. 
• Damaged hardware.
  Due to firmware faults, power surge, overheating or mechanical failure, external hard drive partition might be corrupted. A damaged hard drive is unmountable most of the time. For another, there is a chance that the USB connecting cable has been broken.

In Closing

Mounting is a prerequisite for Mac to recognize an external hard drive. Having such an drive not mounting on Mac must be an annoying part. Hopefully, a few fixes can be applied to cope with this issue as introduced in this post. Don’t forget to apply Cisdem Data Recovery to recover the drive data beforehand for fear of losing data.