Summary: If your external hard drive is not mounted on Mac, you can't access data stored on it. Here is how to fix external hard drives, including external hard drives, SD cards and USB flash drives, etc., not mounting on Mac issue without data loss. You can also download iBoysoft Data Recovery for Mac to recover lost data from unmountable external hard drives first.

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May 28, 2013  Ok, heres my problem. I have a 1 TB Iomega eGo backup drive that I got around in December last year. I have used it for time machine backups and, because my MacBook only has 250 GB of storage, all my games, photos, music, movies, TV shows, and other files that I did not need on my computer all the time but did not want to download again. I had something like 300 GB worth of games. Nov 14, 2019 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.

Usually, an external hard drive will be mounted automatically on your Mac once you plug it in, and you can access data on this drive. However, this time, your external hard drive is not mounting or recognized by your Mac. It's annoying when you find that you are unable to mount external hard drive on Mac, just like the user below.

'I have a 500 GB older HP external hard drive, formatted as macOS Extend journaled on MacBook Pro 2014 and I have been using it to do Time Machine backups. Now after updating to macOS Mojave, this external hard drive just won't mount. The main drive shows in Disk Utility but the backup partition is not showing up. I can't do First Aid as it doesn't show up. Any ideas? Thanks! I need help to recover my important files from this unmountable external hard drive.'

So, this article will give you some information about why your external hard drives won't mount on your Mac, as well as teach you how to fix this disk problem as this table shows.

Tips for fixing external hard drive not mounting issue

Before you go further, there are some tips that deserve your attention. When your disk become unmountable on Mac, you should not go straight to reformat this external hard drive, especially when you have important files on it. This is because reformatting will wipe the data on this drive and cause serious data loss if you don't have a copy of a data backup.

On the contrary, you should stop using this external hard drive right away. The reason for such cautiousness is that any further operation is very likely to overwrite your original files and make them irrecoverable.

Key takeaway:

• Do not format this external hard drive before you get your data back.
• Do not save new things to this drive, or perform other operations like deletion, file removal, etc.

Now, let's go into details about the external hard drives not mounting on Mac issue.

Why an external hard drive is not mounting on Mac?

You probably go crazy because you don't know why this external hard drive is not mounting on Mac. As a matter of fact, this problem could be caused by many factors, such as damaged file system, virus attack, unsafe ejection or any other improper operations.

Here are some common ones.

1. A damaged file system: If your external hard drive is attacked by virus or if you abruptly eject this drive, it's likely that the file system of this disk would be damaged or corrupted. As a result, the operating system is unable to recognize this disk, and the disk will not be mounted or read by macOS.
2. Connection problems: Another reason that your external hard drives is not mounting on Mac could be a dirty or loose connection between your cable, USB-C multi-adapter, Thunderbolt 3, or other connecting ports. A clear, clean, snug and fit tightly connection is the premise of mounting an external hard drive successfully.
3. Hardware issue: Also, problems related to hardware could also make the disk unmountable, especially when your external hard drive has too much bad sectors or have been physically damaged.

But no matter what the reason is, the first and most important thing for you probably is to fix this disk problem.

Basic suggestions on external hard drive not mounting problem

In case you miss anything necessary, you can also have some basic checks as following when you are unable to mount an external hard drive on your Mac computer.

1. Re-plug your external hard drive to another port or try another USB cable. A faulty connection, though it is foolproof, is often the key to fix the external hard drive not mounting issue, in that users always forget to check if the port is wobbly or if the cable is broken.

2. Try a super slow jam. Strange but true, some users found that their external will mount properly when they plug it in exceptional slow motion. However, if they try and plug in the external hard drive normally, the Mac don't recognize the disk.

3. Check your Finder Preferences. When your external hard drive is not mounting on the desktop, you can open Finder, choose 'Preference' (or press Control +, ) and check 'External disks' both in General tab and in Sidebar tab to show your external hard drive on your Mac computer.

How to fix external hard drives not mounting on Mac issue without data loss?

After knowing what possibly makes your external hard drive unmountable, you can set out to fix this issue on your Mac. There are three solutions suggested in this part, and you can try them one by one to troubleshoot this disk problem without data loss.

Solution 1:Manually mount this external hard drive in Disk Utility

If your external hard drive is not mounted on the desktop or in the Finder, you can try to mount it manually in Disk Utility which is a native disk management tool in your Mac. This is one of the easiest solutions, so you can have a bash.

1. Click Go at the upper left of your desktop and go to Utilities, then launch Disk Utility on your Mac computer.

2. Click on 'Show All Devices' in View option to list or connected drives.

3. Choose the unmountable external hard drive in the left sidebar.

3. Select Mount in the top center of Disk Utility.

However, if you find that your external hard drive is not showing up in Disk Utility, it is very likely that your disk is suffering some physical damage. In this case, you need to send it to a local data recovery service. But if the Mount option is grayed out but you can see this external hard drive in Disk Utility, you can try another solution then.

Solution 2:Repair this unmountable external hard drive with First Aid

The second suggestion is First Aid in Disk Utility. First Aid is a very simple tool that is built in your Mac, and it is able to detect and repair directory damage and other disk errors. You are advised to run the tool more than once to ensure you are receiving a consistent result. Follow the instructions and you can correct various disk-related errors via this useful software.

1. Go to Utilities and launch Disk Utility on your Mac computer.

2. Select the unmountable external hard drive on the left sidebar.

3. Select First Aid in the top center and click Run.

Solution 3:Fix the external hard drive not mounting issue by reformatting

If your external hard drive still can't be mounted in Disk Utility after you perform First Aid or First Aid failed to repair it, your drive should have some serious errors like file system corruption.

Under this circumstance, many Mac-noobs would choose to search on Google for solutions when Disk Utility can't repair this disk. Most of you are told to reformat this drive. However, it's not a good idea for people who have important files on this drive. It could be precious family photos, valuable work documents, or any other files.

Instead, if you don't have a copy of a data backup in hand, using this step-by-step guide to recover lost data from this unmountable external hard drive is better than format it directly.

How to recover lost data from unmountable external hard drives on Mac?

As long as your external hard drive doesn't have any hardware problem, fortunately, you can retrieve your files with professional Mac data recovery software - iBoysoft Data Recovery for Mac with no fuss.

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• Recover lost data from unmountable, formatted, inaccessible, unreadable, corrupted external hard drives.
• Supported storage devices: external hard drives, USB flash drives, memory cards, SD cards, etc.
• Supported file types: photos, videos, audio files, documents, emails, etc.
• Suppported Mac OS: macOS 10.15/1.14/10.13/10.12 and Mac OS X 10.11/10.10/10.9/10.8/10.7.

Read-only & risk-free

Tutorial for external hard drive data recovery on Mac with iBoysoft Data Recovery for Mac

1. Free download and install iBoysoft Data Recovery for Mac on Mac.

2. Launch iBoysoft Data Recovery for Mac.

3. Select the external hard drive that is not mounting and click 'Next' button to scan for all lost data.

4. Preview the searching results, choose files you need, and click 'Recover' to get them back.

Note: You need to save the recovered files to another usable drive. By this means, you will not lose them again when you move forward to the steps to fix not mounted external hard drives in the following part.

5. Have a check to ensure you have got all lost data back.

After having successfully restored all data on this drive, you can set out to erase this external hard drive to fix the disk not mounting on Mac issue.

Tutorial to reformat unmountable external hard drives on Mac

1. Launch Disk Utility.

2. Click the icon of your unmountable external hard drive on the left sidebar.

3. Click on the Erase button function on the top of the Disk Utility window.

4. Complete the related information (name, format, scheme), then click Erase button to finish reformatting.

After reformatting, your external hard drive will be assigned with a new file system. And you can go ahead to mount this drive on your Mac normally.

Conclusion:

If your external hard drive like a hard drive, an SD card, a USB flash drive, etc. is not mounting on your Mac, don't be panic. Most of the time, you are going to fix this disk problem with the solutions above. Moreover, if you worry about data loss when the disk becomes unmountable, you can use iBoysoft Data Recovery for Mac to recover your files first. Remember that, no matter what disk problem you meet, you should perform hard drive data recovery before reformatting the problematic drive.

Get a data lifeguard for Mac

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.

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 why this is happening and how you can get an external drive to appear on your Mac and get recover data to access to your documents.

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

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.

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Start with the basics:

1. 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.
2. 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.
3. 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.
4. Reboot your Mac. Sometimes, if a USB disk won't boot, the cause is macOS issue. Hopefully, some data damage that 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.
5. 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.
6. 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.
7. 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.
8. 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

1. Go to the Finder menu and select Preferences (Cmd+comma).
2. From General tab tick 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 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 app, 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

If your drive is having 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.

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To run Fist Aid on an external hard drive:

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1. Open Disk Utility. You can searching for it using Spotlight Search or via Finder > Application > Utility
2. 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 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 and USB drives and camera cards.

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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:

1. Connect your drive to the Mac.
2. Quit all other applications on the Mac, especially those that may be trying to access the external drive (e.g. iPhoto, Words)
3. Launch Disk Drill.
4. 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.
5. 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.
6. Now click Rebuild (or Recover) next to the file(s) you are trying to recover. Once the scan is finished - it may take some time if the files are large - a list of files will appeal.
7. Next, click Mount Found Items as Disk button on the bottom-left below the scan results.
8. Disk Drill “strongly suggest saving the files to a different drive than the one you are trying to recover files from. Saving to the same drive substantially lowers your chances of recovery.”
9. A drive icon will appear, which once you double click will give you the option to open the files as you would do before they were lost. Drag them to another location, such as your desktop or a folder on your Mac.
10. Open the files to ensure they have been recovered properly and safely eject the external drive.

Disk Drill does have other ways to recover lost files but assuming there aren’t complications, this method is the most effective. Disk Drill Pro recovery app is available from Setapp, along with dozens of Mac apps that will make your life easier. Never have to worry about a crashed or corrupted external drive again.

A few more tips on getting your files back

1. Macs and third-party apps that look after Macs, such as Disk Drill and iStat Menus come with a S.M.A.R.T. (also known as Self-Monitoring, Analysis and Reporting Technology) status monitor. If a SMART check reports errors, then it could mean the hard drive is at risk of failing completely. Within Disk Utility and Disk Drill, there are several solutions for this: Repair Disk Permissions and Repair Disk. If neither work, it’s recommended that you backup all of the data from the disk, erase, then run a SMART check again. The external hard drive should show up as Verified.
2. Partitions can get lost within hard drives, temporarily hiding all of the information contained within. Disk Drill can help to identify and restore this information.
3. Within Disk Drill, you can restore data when a hard drive is damaged or add formatting, which is also something Disk Utility can help with.
4. CleanMyMac, another useful app available from Setapp, can help you identify external hard drive errors and repair them. It is an essential tool worth trying when you’re having external hard drive difficulties.

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Alternative ways to recover data from an external hard drive

Reset the System Management Controller (SMC) if your Mac shuts down when you plug in an external hard drive. Then use a different port to connect the external hard drive. If you’ve got a battery that you can’t remove:

• Shut down and unplug the power adapter
• Press Shift-Control-Option and the power button at the same time. Do this for 10 seconds
• Release all keys
• Plug the power adapter back in and switch your Mac back on

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For Macs with removable batteries, you need to switch them off, remove the battery, then press and hold the power button for 5 seconds. After that, put the battery back in, plug in the power adapter and switch the power on again.

What’s your file format? One reason your Mac isn’t recognizing the hard drive is the file format. Windows uses NTFS file formats, while Macs, up until the introduction of Sierra, have used HFS+. Now, Apple has introduced the Apple File System (APFS) for newer operating systems. It is possible to format a hard drive so it can be read on Mac and Windows computers, providing you format using exFAT. However, if you’re having problems accessing the files and the issue is due to formatting, you will need to connect it to a device it can be read on, and then format the files correctly for the computer you are going to use it on next.

How to make Ext2/Ext3 drives readable on Mac

The common issue is Ext2- and Ext3-formatted drives are not readable on macOS. There are two ways to access such external drives on your Mac – via Linux OS or FUSE system. The easiest would be installing Linux to a secondary drive or virtual machine.

If you go with Linux installation, dual boot your Mac with Linux on another drive and use FAT32 as a transfer intermediary. If you don’t have a drive to install Linux to, use virtual machine as an interface for it. Transferring can be done the same way – with FAT32, or via network.

Another option for reading Ext2/Ext3 disks is mounting disk with Filesystem in Userspace (FUSE). Basically, it works as an extra interface enabling file system access via specially installed modules. Here’s how to mount drives with FUSE:

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1. Install FUSE for macOS or MacFUSE as well as fuse-ext2 module.
2. Use the following Terminal command to enable Disk Utility’s debug menu and see all partitions: defaults write com.apple.DiskUtility DUDebugMenuEnabled 1
3. Attach your Ext2/Ext3 drive and locate the device name via Disk Utility.
4. In your user account, create a folder to be used as a mount point.
5. Use the following Terminal command to mount the drive as read-only: fuse-ext2 /dev/disk2s2 /Volumes/mountpoint
6. For write support, use the command: fuse-ext2 -o force /dev/disk2s2 /Volumes/mountpoint

And that’s not the only case where Terminal helps you access external drive.

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Employ the handy all-powerful Terminal, which always comes forward with solutions for difficult problems. Especially if System Information does recognize the USB or hard drive, but continues to hide it from you, disconnect the drive and try to find it using the Terminal, which you can find in Applications > Utilities.

• Once in the Terminal, type in the command diskutil list
• A list with information about volumes and drives should appear
• Look for a section labelled /dev/disk_ (external, physical)
• Make a note of the whole line after the word disk
• Now put the following command into the Terminal diskutil info disk followed by the number or digits assigned to that disk
• Now you should see detailed information about the drive, therefore confirming that your Mac can and does recognize it
• Eject using the Terminal by entering the command diskutil eject disk followed by the number or digits assigned to that disk
• Physically remove the disk from you Mac
• Plug it back in and your Mac should recognize it

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Console is also reliable when it comes to solving tricky problems, although it isn’t always that easy to use. You can find Console under Applications > Utilities > Console. Console shows if an external drive or any error is detected under the Errors and Faults tab. If no errors show up, then the problem is not caused by the device.

To sum up, there are lots of potential solutions for a Mac not reading an external hard drive. If we were to pick one, Disk Drill seems to be the most well-rounded, offering plenty of customizations and power in an easy-to-use interface. Disk Drill Pro recovery app is available via Setapp, along with 150+ Mac apps that strive to make your life much much easier. At the very least, you’ll never have to worry about a crashed or corrupted external drive ever again.