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Most of the time, when you connect an external hard drive to your Mac’s USB port, you soon see it mount on the desktop. Apple likes to ensure these are easy to find, so they also appear in the Finder in the left-hand column under Devices, since Mac’s treat them the same way as another computer.

The Disk Utility included with Mac OS X is powerful, and it should handle all the functions you need it to perform. It’s a bit like the Disk Management tool built into Windows, but more capable and, thanks to Recovery Mode, easier to access from outside the operating system.

However, sometimes, an external hard drive doesn't show up. It’s annoying, especially when you need to transfer something right then. And besides, there can be a risk that data on the external USB pen, hard, or flash drive is corrupt, which means you can’t transfer what you need between devices at all.

Corrupt data can be one reason your Mac won't recognize an external drive, but there are other reasons too. Let’s take a look at why this is happening and how you can get an external drive to appear on your Mac and get recover data to access your documents.

How to fix an external disk drive that won't show up on a Mac

Disk Utility can find and repair errors related to the formatting and directory structure of a Mac disk. Errors can lead to unexpected behavior when using your Mac, and significant errors might even prevent your Mac from starting up completely. Apple: MacBook Pro disk utility - disk0s2 not mountedHelpful? Please support me on Patreon: thanks & praise to God.

Why an external disk drive is not showing up? There could be a few reasons why a USB flash drive isn’t making an appearance.

Access an External Drive Not Showing on Mac

Get a huge set of top utilities for troubleshooting external hard drives not mounting on a Mac

Start with the basics:

Check whether the drive is properly plugged in. It sounds obvious, but since this relies on a wire - either a USB cable or HDMI cable - if it’s not connected properly then it won’t appear on your desktop.
Faulty cable. Assuming it’s plugged in correctly, not wobbly or loose, the cable could be at fault. Try connecting the same device with a different cable.
Damaged USB or flash drive port. It could be a hardware issue with the Mac. If you’ve got another port, try connecting the device to that one.
Reboot your Mac. Sometimes, if a USB disk won't boot, the cause is a macOS issue. Hopefully, some data damage can be fixed by restarting. Choose the Apple menu > Restart. Or press and hold the power button and, when a dialog box appears, click the Restart or press R. Restarting your Mac essentially clears your macOS’s memory and starts it up fresh.
Incorrectly formatted drive. Not every external drive is optimized for Macs. It could be that you are trying to connect something only fit to interact with Windows devices. If you’ve got a PC or laptop, it’s worth connecting and seeing if you can access the files through another device. The best way to look for an incorrectly formatted drive is to go to
Apple (in the top toolbar menu) > About This Mac > Storage.
See if the external drive shows up here. For more information, go to the same menu option, then select System Report.
Mac not formatted to display external drives on the desktop. It could be that your Mac already recognizes the device, but just isn’t showing its icon on the desktop screen. Even if that is the case, the drive will still appear in the left-hand column of the Finder menu under Devices. You should be able to access your drive that way, and, in the Finder menu under Preferences > General, you can check External Drives to ensure that from now on it shows up on your desktop too.
Reset NVRAM. To do this, shut down or restart your Mac, switch it back on and immediately press these four keys together for at least 20 seconds: Option, Command, P, and R. It should look as though your Mac has started again; if it has, release the keys when you hear the second startup chime. Hopefully, the hard drive has shown up now.
Check Apple’s Disk Utility to see if an external drive is showing up. Disk Utility is within System Preferences, or you can find it using Spotlight. If it is visible, then click the option to Mount, which should make it visible on the desktop and in the External Drives option in the Finder menu.

Unfortunately, if none of those options has worked and the external drive still isn’t visible, then it could have crashed, or be well and truly broken. But there might still be a way you can recover the data on the external drive.

How to show connected devices in Finder

Go to the Finder menu and select Preferences (Cmd+comma).
In General, click on External disks to ensure that from now on it shows on the desktop.

In the Sidebar tab you can choose which folders and devices will be shown in the left-hand column of the Finder window.

How to add cloud storages to Finder

You can also mount cloud storage as a local drive on your Mac. By connecting Google Drive, Dropbox, or Amazon to your computer, you get more space for securely accessing and sharing files. For your ease, add cloud drives to Finder with CloudMounter so that you keep them close at hand. You can read detailed instructions on managing cloud storage as local drives here.

Repair the failed external drives with First Aid

The most direct reason your external hard drive could be detected by macOS, but can't be opened is the file system problem.

If your drive is having such problems, you can try to fix them yourself with First Aid and therefore get access to your files. First Aid tool will check the disk for errors and then attempt a repair as needed. It helps to verify and repair a range of issues related to startup HD and external drive problems. If you are able to fix the hard drive or SSD in your Mac (or an external drive) using Disk Utility you will hopefully be able to recover your files.

To run Fist Aid on an external hard drive:

Open Disk Utility. You can search for it using Spotlight or via Finder > Go > Utilities
Check on your external hard drive, click the First Aid tab and select Run to start running diagnostics.

If First Aid successful in fixing errors, the external drive should be available to mount. If the utility is unable to repair issues, your drive truly is broken or formatted using a file system that the Mac cannot read - in this way we suggest you follow the next steps to recover data from a damaged disk drive.

How to recover data from a crashed drive

Thankfully, there is an app for that. Disk Drill is the world’s premier data recovery software for Mac OS X. Powerful enough to retrieve long-lost, mistakenly deleted files from Macs, external hard drives, USB drives, and camera cards.

Get a file recovery app

With Setapp you get a pack of professional tools for file recovery and Mac maintenance.

An easy way to recover lost files on an external hard drive

Providing you already have Disk Drill Pro version, which you can get automatically by downloading from Setapp:

Connect your drive to the Mac.
Quit all other applications on the Mac, especially those that may be trying to access the external drive (e.g. iPhoto, Words)
Launch Disk Drill.
Click on the external drive that you are trying to recover files from. If it has partitions, you will see all of them. If, however, you still don’t see any volume to the external drive then you may need to try some of the steps above again or read the Disk Drill Scanning FAQs.
To avoid the external drive being accessed during the recovery process, click Extras next to the drive or drive partition or file, then select Remount Volume As Read Only. A padlock will appear, protecting the drive during the process.
Now click Rebuild (or Recover) next to the file(s) you are try

Disk Utility Mac