15 Worst Mac Hard Drive Problems with Solutions

While iMac and MacBook are the most agile computers, they are not immune to hard drive issues. Numerous problems can affect Mac hard drive, solid-state drive, or hybrid drive that make disk repair or data recovery difficult. The next section describes the 15 worst Mac hard drive problems with their solutions.

1.  Mac external hard drive not mounting or is unrecognized

Problem: When you connect an external hard drive to Mac, it mounts and shows up on the Desktop. It also appears in Finder. However, sometimes, the disk can fail to mount when you connect it. In such a case, it won’t even appear in Finder.

Solution: Some common fixes you can try are:

  • Set your Mac to show all mounted drives on the Desktop.
  • Go to Finder > Preferences > General, then select External Drives.
  • Unplug and re-plug the drive.
  • Try to connect it with a different cable.
  • Use a different USB port to connect it.
  • Try connecting it to another Mac.

If none of the above solutions works, there might be something wrong with your external hard drive. Try to back up your hard drive via Disk Utility or a third-party cloning utility, so that later you can erase and reformat the drive with a new file system. However, if there is no backup of your data and you are unable to clone the troubled hard drive, then opt for a Mac data recovery software to recover data from the unmounting Mac hard drive.

Read Case Study: Whooping 94% data recovered from unmounted external drive on MacBook Pro

2.  Mac hard drive running slow

Problem: Aging and prolonged usage can slow down a Mac. Also, a lot of other factors can degrade your Mac performance, like hard drive becoming full, macOS being outdated, several login items enabled, many apps running in the background, hardware issues, etc.

Solution: There are several things you can do to give your Mac a performance boost:

  • Delete large unwanted files, unused apps, and duplicate data from the hard drive.
  • Clean up the Desktop and login items.
  • Update your macOS and third-party applications.
  • See a list of background processes in Activity Monitor and quit the ones you don’t need
  • Upgrade your Mac hardware and firmware
  • Repair your start-up disk with Disk Utility
  • Remove inessential plugins, widgets, and Internet caches from Safari

The above list of activities often looks simple, but it isn’t. Taking out the time to manually clean up Mac hard drive and perform other tune-up tasks can be frustrating. So, avoid all hassle and try Stellar SpeedUp Mac. This product automatically removes system junks, large unused files, duplicates, old apps, and unused login items from Mac hard drive with the click of a button.

3.  Mac hard drive has failed SMART status

Problem: Mac hard drive uses SMART (aka Self-Monitoring, Analysis, and Reporting Technology) to monitor internal disks and to check for issues. If the SMART check on your Mac hard drive reports an error or failure, it usually means the hard drive is about to fail permanently.

Solution: There still may be hope for your hard drive. To check all recovery possibilities, follow these steps:

  • For an external hard drive, open Disk Utility, then select the failing hard drive from the left pane. Click First Aid and then click Run to initiate the repair process.
  • For startup disk (Macintosh HD), start or restart your Mac and immediately press-hold Command + R keys. Release the keys when the Apple logo appears. On the macOS Utilities window, select Disk Utility, then click Continue. Select the startup disk from the left pane and click First Aid. Click Run to repair the startup disk.
  • If the repair process doesn’t work, back up all the files present on the disk and then erase it.
  • Once the erase procedure completes, check the disk’s SMART status, which should ideally show the hard drive status as “Verified”.

If none of the above solutions works, you may need to repair your hard drive or replace it with a new one. But you can leverage Stellar Data Recovery Professional for Mac to recover lost files from your hard disk and then proceed with the replacement or repair of the affected hard drive.

4.  Mac hard drive’s partition is deleted

Problem: While trying to perform partition resizing or reformatting operations, many users report accidentally deleting their partitions containing important data. Also, due to issues such as partition table damage, technical trouble with the drive, bad sectors, etc. one or more hard drive partitions can get accidentally deleted.

Solution: Restore the lost or deleted partition with the help of Time Machine backup. However, in absence of backup, use Stellar Data Recovery Professional for Mac software to find the deleted partition(s). This application helps locate deleted partitions on any APFS, HFS, HFS+, FAT, NTFS, or ex-FAT based storage drive. It can quickly revive deleted partitions on your iMac, Mac Pro, MacBook Pro, MacBook Air, or Mac Mini. Also, if the partition(s) on your Mac fails to mount, then this software helps to recover the partition data easily.

5.  Mac hard drive making a clicking noise

Problem: Mac hard drives typically contain platters on which a magnetic arm reads/writes data. The platters can get damaged by a drop or jerk. If you hear a clicking noise coming from your Mac hard drive when you boot your Mac, this could mean your hard drive has suffered physical damage.

Solution: In such a scenario, there isn’t much you can do except:

  • Back up all your important data.
  • Run the Apple Hardware Test.
  • If you can’t back up your drive, clone it in its present state with Stellar Drive Clone.

You probably need to replace your hard drive with a new one or at least get it checked by professionals. DO NOT attempt to open it yourself as that could further the damage and lead to permanent data loss.

6.  Mac hard drive ‘couldn’t unmount disk’ problem

Problem: While trying to repair disk through Disk Utility, you may witness an error that says ‘couldn’t unmount disk’. When this happens, you can’t erase or partition the drive. This happens when the boot drive has been somehow modified or is being used by some other process or application.

Solution: Run ‘First Aid’ on the drive that is throwing the error by using Disk Utility in macOS Recovery mode. Alternatively, you can use a bootable USB drive. If ‘First Aid’ doesn’t fix the error, then you may need to reformat the hard drive.

7.  Mac hard drive’s encryption password is lost

Problem: Many of you use Apple File Vault to encrypt data on your Mac hard drive. File Vault uses XTS-AES-128 encryption with a 256-bit key to help prevent unauthorized access to the data on the startup disk. But every encryption works in conjunction with a decryption key that decrypts the data before it can be accessed. Mostly, this decryption key is a password chosen by you. If you lose or forget your decryption password, you lose access to your data permanently.

Solution: Make sure you are typing the password correctly. Turn off the Caps Lock and choose the Show Password option just to be doubly sure. If you’re still locked out, try one of these:

  • If the password field shows a question mark, click it to display a password hint. The hint might help you to remember the forgotten password.
  • Try to log in with the Apple ID password that you use for iCloud.
  • Reset the password using your Apple ID. This resets your keychain, and you need to authenticate again to access any of the items that were stored in your keychain.
  • Have an administrator reset the login password.
  • Use the recovery key that you noted down when you turned on File Vault disk encryption (for this File Vault must be on).
  • Reset password using the Reset Password assistant (for this File Vault must be on).

If none of the above steps work, contact Apple Support for help!

Related Blog: How to Encrypt, Decrypt, and Recover Deleted Mac Files

8.  Mac hard drive data loss

Problem: Data loss from any hard drive is inevitable. There could be any reason for data loss such as technical failure, physical damage, virus/malware attack, system crash, accidental deletion, drive erasure, etc.

Solution: Recovery of lost data from a hard drive is possible if you stop using the drive immediately to prevent any overwriting. Next, download the trial version of Stellar Data Recovery Professional on your Mac. Scan the hard drive for recoverable data then preview the scanned items.  When satisfied with the recovery result, activate the software to recover all your missing data to different drive location.

9.  Bad sectors in Mac hard drive

Problem: Detecting bad sectors on your hard drive isn’t easy. You might suspect that your Mac hard drive has started developing bad sectors if some information suddenly goes missing or the drive throws error accessing a file. For example, you saved a file normally but on trying to access it later, the OS shows an I/O error that due to a bad block it can no longer read.

Solution: There are several fixes to this problem:

  • Check the SMART status of your hard drive by using Disk Utility.
  • Clone the drive using Stellar Drive Clone and save the copy on another physical drive.
  • Boot into macOS Recovery mode then go to Disk Utility > First Aid. Click Run to repair the hard drive. Keep running First Aid until it says there are no errors.
  • If the repair doesn’t work, back up the drive, then erase it, and finally restore the backup.

10.  Unable to partition Mac hard drive

Problem: Partitioning a hard drive is a fairly simple task by using Disk Utility. But sometimes, Disk Utility fails to create partitions on a hard drive or perform other partitioning-related operations.

Solution: Try Stellar Partition Manager for all your hard drive partitioning needs on Mac. This software works on the macOS Sierra and earlier versions and helps perform tasks like creating partitions, deleting partitions, formatting partitions, resizing partitions, hiding or revealing partitions, etc.

11.  Mac hard drive ejecting itself

Problem: Some of you may have tried replacing your Mac CD/DVD drive with a large capacity hard drive. By doing this, you’ve augmented your Mac’s storage capacity. But you may have also noticed auto hard drive ejection issue after a few minutes of drive idleness.

Solution: To resolve the eject issue, you need to tweak the power management settings of your Mac, as shown here:

  • Go to Finder > Applications > Utilities > Terminal.
  • On Terminal, type “pmset –g | grep disksleep” and hit Return.
  • Check the value of disksleep. If it is low, you need to provide a significant number.
  • Type “sudo pmset –a disksleep #” (here replace # with a suitable number) and hit Return.
  • Provide the admin password when prompted.
  • Check the changed sleep value by using “pmset –g | grep disksleep” command.

The above solution will fix the drive auto-eject problem. Now, you can use the hard drive to save and access data normally.

Related Blog: Recover Data Lost after Ejecting Mac USB Hard Drive Cable Abruptly

12.  Mac hard drive is not detected in Windows

Problem: When you connect a Mac-based storage drive on a Windows PC, it won’t appear on File Explorer. This issue arises due to the incompatibility of file systems. Your storage drive may be formatted in the APFS or HFS+ file system, which is compatible exclusively with macOS. No other operating system is harmonious with the proprietary file system format of Apple.

Solution: To fix the issue, do the following:

  • Back up all the data from the storage drive from its compatible operating system.
  • Format the drive in the ex-FAT file system. (You can even format your USB flash drive in FAT32, but it will only allow storing of files with a size limit of 4 GB.)
  • Restore the backed up data to the storage drive.

Now, you can use the storage drive in both Mac as well as Windows computers. Windows can read-write on ex-FAT as well as FAT32 file system formatted storage drive.

Related Blog: How to Recover Data from Mac Hard Drive on Windows

13.  Mac hard drive space is disappearing

Problem: Low free space is a concern for Mac users if they are using a low capacity storage drive (say 128 GB SSD). “Your startup disk is almost full” is a common error seen by such users. Even if you keep your essential data in iCloud and large multimedia files in an external storage drive, your Mac storage drive free space will disappear automatically. This happens due to the buildup of junk files, temporary files, caches, logs, and leftovers of application.

Solution: To resolve the drive space disappearing issue, you need to make more space available on your startup disk by deleting temporary files:

To remove temp files and caches:

  • Open Finder from Dock.
  • From the Menu Bar, click on Go and then click Home.
  • Click the cog icon from the top pane and select “Show View Options.”
  • On the popup window, select the “Show Library Folder” checkbox, then close it.
  • Go to Library > Caches.
  • Delete all the caches.

Alternatively, you can do the following:

  • Open Finder from Dock.
  • From the Menu Bar, click on Go then click “Go to Folder.”
  • In the dialog box, type ~/Library/Caches, then click Go.
  • Delete all caches.

You can delete all the temporary files from specific folders present in the Library folder, such as Logs, unneeded iTunes files, and Application Support files. This frequent temporary file removal will increase free space on your Mac and prevent the drive disappearing issue. Alternatively, you can use Stellar SpeedUp Mac utility to perform the task with a click of a button.

14.  Mac hard drive can’t be repaired

Problem: By using the First Aid tab present in Disk Utility, you can fix your hard disk drive or other storage drives for errors, bad sectors, etc. But this is not always the case. Sometimes, you’ll encounter the message “Disk Utility can’t repair this disk.” This error occurs because Disk Utility fails to repair your storage drive.

Solution: Use the “file system consistency check” (fsck) command in Single User Mode to review and repair the basic structure of your storage drive. But, first off, back up the drive to another external storage medium to ensure you don’t lose data due to troubleshooting error. Next, perform the following steps:

  • Start or restart your Mac then immediately press-hold Command + S keys until white text appears on the startup screen. Your Mac will boot into Single User Mode.
  • On the command prompt, type “fsck –fy” and hit Return. Don’t interrupt till the command finishes, as it can incur data loss.
  • When you see the message “The volume was modified” or “The volume Macintosh HD could not be repaired,” use the above command again.
  • Use the command multiple times until you get the message “The volume Macintosh HD appears to be OK.” Type exit to restart your Mac.

Related Blog: 8 Ways to Repair Failing Mac Hard Drive

15.  Mac hard drive is not showing up in Disk Utility

Problem: The Mac storage drive fails to show up in the Disk Utility window.

Solution: Mac hard drive not appearing in the Disk Utility window is one of the worst problems that a storage device could face. In most cases, the device is dead either completely or partially. As far as an unmounted Mac hard drive is concerned, the drive still appears in the Disk Utility—though the drive seems to be greyed-out. Fortunately, a Mac hard drive recovery software rescues the stored files from the unmounted media, and later the drive can be erased for reuse.

In case of a dead Mac hard drive, it is advisable to replace the drive after data recovery is performed by a data recovery service provider.


In this post, we outlined the worst problems you face with your Mac hard drive, solid-state drive, or other storage drives and partitions. But by implementing the solutions shared in the post, you can avoid data loss. But keep in mind, critical troubleshooting steps must be performed only after taking a full backup of the storage medium.

In case you lose your valuable data during or after performing the troubleshooting steps due to inadvertent errors or otherwise, leverage Stellar Data Recovery Professional to get back your data. The software is user-friendly and recovers lost data in 3 key steps: Select, Scan, and Recover.

  1. Kevin Ray December 30, 2019
    • Vishal December 31, 2019
  2. Keith Berger September 24, 2019
    • Vishal September 25, 2019
  3. Erika Latimore August 23, 2019
    • Vishal August 27, 2019
  4. Bruno July 24, 2019
    • Vishal July 25, 2019
  5. George Erickson January 24, 2019
    • Vishal January 25, 2019
  6. tarun naveen October 10, 2018
    • Vishal October 11, 2018
  7. Elbert Graves April 27, 2018
    • Vishal April 27, 2018
  8. Gilda Caldwell March 22, 2018
    • Arpana March 29, 2018

Leave a Reply

Your email address will not be published. Required fields are marked *

Time limit is exhausted. Please reload CAPTCHA.