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How to open external hard drive not recognized by the Mac

open unrecognized external hard drive

Does your Mac not recognize an external hard drive that you have connected to the USB port? It's a lot of trouble if you urgently need the files it contains. But do not despair, because in this guide we will see how to open external hard drive not recognized by the Mac and be able to access its contents again with simple steps.

When you connect an external hard drive to the USB port on your Mac, you'll normally see it mounted on the desktop. You can also see it in the Finder in the left column below "Devices". If not visible, probably damaged, defective or not in the correct format. In this guide, you will be shown how to understand whether the drive, cable or USB / FireWire is to blame and how to solve the problem to access data on your drive.

How to repair external hard drive not recognized by the Mac

This guide assumes of course that you have an external drive such as a hard drive that can connect to your Mac via the USB or Firewire port.

Preliminary checks

There are a number of reasons why the hard disk, flash drive or SSD disk may not be displayed on the Mac, even though they are properly connected. The causes could be incorrectly formatted, a damaged drive, a defective (or inadequate) cable or something else. If you perform the following steps you will be able to identify the cause first and therefore solve the problem.

  • Make sure your Mac is set to show units mounted on the desktop. Go up Finder> Preferences> General and make sure there is a check mark next to "External units".
  • Check that the unit is connected correctly. It seems obvious, but one of the main reasons why external units fail to display because the unit does not receive enough power from the cable. If the unit is powered by a USB cable, it is necessary to check that sufficient power is supplied to the unit. Older Macs may require a USB power cable. A cable that splits into two USB connectors that both need to be connected to the Mac, to provide enough power to the unit. Similarly, make sure that the unit does not have an external power supply that must be connected to the electrical outlet.

Make sure this is not the reason with further evidence. Try using a different USB cable with the external drive to see if this solves the problem (similarly, if you are using a USB port through a hub, make sure this is not what is causing the problem).

Also check that your Mac's USB port is not the problem. Try connecting to a different USB port. Or if you only have one, connect another device and see if it works well.

Try another Mac to see if you can access the unit.

Try connecting it to a PC – perhaps the PC formatted drive, so it can't be read by your Mac.

connect to the PC

Procedure to view external hard drive

To try to open an external hard drive not recognized by the Mac, open the program "Disk Utility?From Apple to check if you can show the Mac to the disk. Find the Disk Utility app by opening it Spotlight (cmd + space bar) and start typing Utility Disk, press enter to open the program. Choose View> Show all devices.

If you can view the hard drive in Disk Utility, go to "Volume"And click on it, select"Monta". If your Mac has already mounted the unit, the option "unmount".

If the "Volume" is not listed, your Mac cannot access the unit. The "Mount" option is deactivated.

The only choices allowed are SOS, Clear is Restore. The command SOS check the disk errors and then repair it if necessary. The function Restoration allows you to erase the contents of the unit and replace it with data from another party. While Clear delete all data stored on the disk. These last two procedures cannot be canceled. If you need the data on the disk, do not select for any reason Clear or Restore!

You could try the SOS function. Click on the "SOS"And select"Run". If after running SOS the Mac finds errors that it can correct you could see the option "Repair Disk".

Repair Disk

If the Mac is unable to repair the disk, it is likely that the drive is formatted using a file system that the Mac cannot read, or damaged. If this last hypothesis is true, we suggest you follow a procedure for recovering data from a damaged disk.

Hard disk formatting formats

Some useful information on file formats: Windows PCs use the file format NTFS, while Mac computers, prior to Sierra, used the file format HFS +. To complicate matters, Apple has introduced a new file system called the Apple File System (APFS) in High Sierra. However, you can format a disk drive so that it can be read by Windows and Mac computers. To make sure that the unit can be read by Mac and PC, you must format it using exFAT or the old man FAT32. The hard drive may have been formatted using a different file system (such as on a Windows PC). In this case, if you need to access the data on the unit, you must connect the unit to a Windows PC that recognizes it, so you can copy the data before moving on to the next step.

hard disk formatting

If you don't need to use the data on your hard drive, click Clear and the Mac will format the disk. If you still can't access the data on the disk, you could try these options:

To avoid damaging an external hard drive, make sure the external drive is always properly disconnected after using it. Do not simply disconnect the USB cable. To disconnect the unit from your computer, you can right-click (control-click) the icon on the desktop or in the Finder and choose Eject. It sounds incredible, but most problems on external drives are caused when the disk is removed without properly ejecting it.