Mac not detecting hard drive? Find the solution here!

An external hard drive is helpful if you want to store large files from your Mac. In addition, using an external hard drive allows you to store much more data, mainly if your Mac is limited by its built-in hard drive.

An external hard drive also helps to take data from your Mac to another location or use it on multiple Mac computers. If you frequently get the message that your Mac is running out of disk space, it is also advisable to move data to the external hard drive. Moving data to a fast (SSD) hard drive will speed up your Mac considerably because running out of disk space will slow down your Mac.

However, it also happens that the hard drive is not recognized by macOS. Again, this may be due to improperly disconnecting your hard drive. For example, suppose you do not remove the hard drive properly first. In that case, the external drive may not be recognized after reconnecting it.

Mac does not detect external hard disk

Turning off Mac and disconnecting the external hard drive

If the external hard drive has always worked and was visible in Finder. Then it may help to turn off the Mac (not reboot), and disconnect all USB devices attached to the Mac. Then wait 5 minutes, turn the Mac back on and if the Mac has wholly restarted, then only reconnect all USB devices.

The Mac will reconnect to the attached USB devices, and the external hard drive might be found.

Check external hard drive cables

To prevent problems with the connection, you should check all cables to and from the external hard drive and your Mac. For example, think of the power cable to the outlet, the USB cable(s), etc. Always use the official cables to connect, not alternative/counterfeit cables or USB hubs (a USB cable with multiple USB inputs).

If you use alternative cables, a connection problem may occur between your Mac and the external hard drive. This may cause your Mac to not find the external hard drive.

External Hard disk shortcut not visible

First of all, we will check if the hard drive is visible in Finder. The hard drive is connected in macOS but is not visible.

Open Finder. At the top of the menu, go to Finder and then to Preferences. Next, go to the General tab and check that the hard disks and External disks are checked.

Show hard disks or external hard disk on desktop in macOS

The shortcuts to the drives are displayed on the macOS Desktop. If you do not see the shortcuts proceed to the next step.

Disk Utility

You can use the Disk Utility to detect and resolve the external hard drive problems.

Press the Command ⌘ + Spacebar keys on your keyboard. In Spotlight type: Disk Utility and Start Disk Utility. Select your external hard drive in the left menu and then click Disk First Aid.

First aid external hard drive in macOS

Check for and resolve any problems by following the instructions. If you cannot find the disk or there are still problems, proceed to the next step.

Format the external hard drive

If you see your hard drive in the Disk Utility but cannot open it on your Mac, you may have a problem with the drive format.

In this case, you will need to reformat the drive. PCs with the Windows operating systems use the New Technology File System (NTFS). On the other hand, Mac computers with macOS operating systems use the Hierarchical File System (HFS+).

By default, USB sticks and other external drives are formatted with the NTFS file system. This works great on PCs, while Macs can read data in the format but have trouble writing it. Fortunately, you can format your external drive with the File Allocation Table (FAT32) or Extended File Allocation Table (ExFAT) file system.

Format FAT32 is fully interchangeable with all Windows and Mac operating systems versions. Unfortunately, this particular file system does have file size limitations. The maximum size of supported files is 4GB, which means you cannot write files larger than 4GB. Also, you cannot create a boot disk for Macs within storage media that uses the FAT32 file system.

Suppose you do not use external storage to transfer large files or create executable partitions. In that case, the FAT32 format may be a good option.

ExFAT is a file system format that has an advantage over the FAT32 file system. It has no restrictions on file or partition size. Therefore, you can write a file with 1TB and create partitions of 5TB within the device. Unfortunately, despite the improved data size, some older versions of the macOS operating system are no longer interchangeable with this file system format.

If you have not already started the Disk Utility.

Press the Command ⌘ + Spacebar keys on your keyboard. In Spotlight type: Disk Utility and Start Disk Utility. Select your external hard drive in the left menu and then click Erase.

Erase external hard drive in macOS using disk utility

Select the desired structure, ExFAT, macOS extended (journaled), or MS-DOS (FAT), and click Erase. I recommend the ExFAT structure.

Erase external hard drive as exfat in macOS

Please note that all data on the external hard drive will be erased!

Still not recognized? Or don’t want to erase the data? Then proceed to the next step to diagnose the problem with the external drive.

Console

Press the Command ⌘ + Spacebar keys on your keyboard. Then, in Spotlight type: Console and Open the Console utility.

Disconnect your external hard drive from your Mac. In the left menu, select your device (your Mac). Click the link, Start streaming.

Streaming log to detect hard drive errors in macOS

Now connect the external hard drive to your Mac. If error messages appear in the console, review them and find a solution. You can contact Apple support or search the internet.

Continue reading: 8 tips to fix a Mac that doesn’t start or boot.

Thank you for reading!

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