You often see people asking for help: "I accidentally erased my external hard drive on my Mac," "I accidentally deleted a Macintosh HD in Disk Utility," "I accidentally erased a startup disk on my Mac," and so on at Google. I don't know the exact reasons why people encounter the problems, but I can feel their anxiety. Erasing a hard drive means it wipes all the data stored on the disk, and sometimes it even stops the Mac from booting.
Stay calm. Recovery from an accidentally erased hard drive on a Mac is possible with the right approach. In the following, we'll discuss the workable solutions and explain how macOS handles the disks and files on them. Additionally, you'll learn how to troubleshoot when Disk Utility can't erase a hard drive.
When it comes to erasing hard drives, people must think of Disk Utility and Terminal. The two both are built-in macOS applications that users handle hard drive-related tasks, such as fixing disk errors, changing file systems, mounting/unmounting removable storage devices, partitioning, and even initializing the hard drive.
People always use the Disk Utility and Terminal to accidentally erase their Macintosh HD and external hard drives on their Macs. When macOS receives an erasing command, it processes the whole task as follows:
Absolutely yes! Whether you accidentally erase an external hard drive, Macintosh HD, or even a startup disk, only the file index information is removed. As mentioned previously, although the wiped files disappear from our screen, the actual content of these files still exists on the hard drive.
Therefore, even without a backup, we can still use professional free file recovery software for Mac to get them back. However, for users who accidentally wiped an external hard drive on their Mac, the possibility of recovery depends on whether you have adjusted the security level in Security Options.
| Security Level | Description | Impact on Data Recovery |
|---|---|---|
| Fastest (default) | Delete file index information and its disk-occupying bitmap information. | If no new data is written after the hard drive is erased, the original files can still be recovered. |
| Fast | The data area where file metadata was stored, is filled with zero or random items to make the previous data wiped completely once. | The chances of data recovery will decrease, and even if some data is recovered, it might be corrupted and not opened. |
| Secure | The data area where file metadata was stored, is filled with zero or random items to make the previous data wiped completely in three times. | It is almost impossible to recover files from an accidentally erased external hard drive on Mac. |
| Most Secure | Adopting US Department of Defense standards, filled in with zero or random items 7 times. | Absolutely impossible to recover data from the erased hard drive |
As mentioned above, by default, selecting the "fastest" hard drive erasure method, files are not completely destroyed unless you save new content afterward. Therefore, the following ways can help you retrieve these missing files to achieve the goal of restoring the hard drive, but you must act quickly.
If you regret erasing the disk using Disk Utility or Terminal and your Mac is working perfectly fine, you have three DIY fixes. Here are the details below.
When using Disk Utility, you should notice a "Restore" option in its top menu bar. If you had created a backup or an image of the hard drive before accidentally erasing it, you can follow the steps below to restore it to its previous state.
Note: It can only roll back the hard drive to a specific point in time, i.e., when you created the backup. Therefore, if the available backup does not contain your recently saved files, you should use data recovery software to retrieve them in the first place.
Since its release, Time Machine has been used by users for local file or system backups, to handle situations where an external hard drive or Macintosh HD on the Mac is accidentally erased. The method is especially useful and saves a lot of time if you created a backup of the required files before the hard drive was erased. Here are the steps:
As I mentioned earlier, accidentally erasing a hard drive with Disk Utility doesn't mean the files are permanently removed. Without a backup, the only DIY method to recover these files is to use professional data recovery software.
With so many programs available, you might not know which one to choose. If you ask me to give some suggestions, I would recommend iBeesoft Data Recovery for Mac. Here are the reasons why you can depend on it:
If the primary storage of your Mac (the startup disk) is erased, it loses the files required to boot macOS. When you start the Mac, it may show a flashing folder icon with a question mark, get stuck on a black screen, or repeatedly display recovery options. Although it is the worst-case scenario when accidentally erasing a hard drive on a Mac, you can still resolve the issue by trying the following methods.
Users who frequently use Time Machine should know that it can not only back up your personal files but also create complete macOS snapshots, allowing you to restore the startup disk to an earlier point in time if something goes wrong. If you accidentally erased the startup disk, here is the solution:
The time required for the process will vary depending on the size of the backup. Once the progress completes, your Mac should be able to restart normally.
If you don't have a macOS backup, how can you make an accidentally erased startup disk work again? Reinstalling macOS will be the only manual method available to you. To do this, follow the steps below:
Tip: If you have previously used Time Machine to back up apps, user accounts, settings, or personal data, check the guide to restore them: (support link provided by Apple).
Most times, we can use the above-mentioned DIY methods to solve the data loss issue of an accidentally erased hard drive on a Mac. However, it doesn't always work. If you are in a frustrating situation, the final resort is to contact a professional data recovery service through an online search. They are more skilled at handling complex data loss issues, even if your hard drive has suffered physical damage. If you are not familiar with this type of service, you can take a look at the best data recovery services list, getting to know their pros and cons before choosing one that meets your needs.
When attempting to use Disk Utility to erase an external hard drive or Macintosh HD, you may encounter issues such as the "Erase" button being grayed out or the process being abruptly terminated. While various factors can lead to these problems, but you can always try the following methods to solve them.
In certain situations, even if your external hard drive is connected to the Mac and it appears in both Finder and Disk Utility, it may not be properly mounted, which can prevent you from erasing it. The solution is straightforward: simply click the "Mount" button in Disk Utility.
Sometimes, the inability to erase a hard drive containing multiple volumes because you mistakenly selected just one of the volumes rather than the entire storage device. To address this, go to the Disk Utility menu and select "View" > "Show All Devices", as shown in the screenshot below. Afterward, choose the parent drive and click "Erase".
If the disk you are attempting to erase is severely corrupted, the system may fail to retrieve the necessary information to complete the process. In such cases, you need to repair these errors before erasing it. Follow the steps below:
Once the repair is complete, you should be able to erase the drive. If issues still exist, you can learn more information about CHKDSK for Mac for further troubleshooting.
In simple terms, it serves as an alternative solution to erasing a hard drive via Disk Utility. When it fails to complete this task, using Terminal can be an effective approach. However, I must remind you that accidentally selecting the wrong hard drive or volume may result in permanent important data loss. If you are ready, follow these steps:
Some users may wonder, "Why can't I erase my Macintosh HD?" It is because macOS relies on the files stored on it to operate, keeping the drive in use. If you genuinely need to erase it, you should first back up your data using Time Machine, then follow these steps:
First, please immediately stop using your disk to prevent any data overwriting issues. Then, check for available backups or disk images to restore the external hard drive to its previous state. If there is no backup, consider using software like iBeesoft Data Recovery for Mac to recover important files.
You most likely restored your hard drive using a Time Machine backup or disk image. As a result, it can only roll back to the point in time when you created the snapshot. So, files created after the snapshot will not be restored. To retrieve them, using data recovery software is a viable solution.
If no backup is available, you can try using free tools such as iBeesoft Data Recovery for Mac, TestDisk, or PhotoRec.
Assuming the formatting process was completed, you may have selected a file system format that macOS does not support, such as NTFS. If you need to exchange files between both operating systems frequently, consider using free NTFS software for Mac. Otherwise, you will need to reformat it on your Mac and choose a compatible file system like APFS or exFAT.
A single accidental click may easily erase your external hard drive or Macintosh HD, but restoring it to its previous state is far from simple. Fortunately, the guide can help address such mishaps. Ultimately, to avoid repeating mistakes for losing important data, always be careful when handling the disk and maintain regular backups.
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