How to erase mac hard drive disk utility

Software Downloads. Instructions for installing an internal drive as a bootable or a storage drive in MacOS X. Physically install the drive into the Mac. Power on the computer while holding down the option key. Select Installer. Select Disk Utility. Highlight the drive. Enter Volume information Name, Format, and Scheme. Select Erase. Note: This will erase all data from the drive. Select Partition. Select Utilities. Select the Erase tab. Verify that the correct hard drive is selected in the left column.

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Highlight the drive Select Partition. Select Install OS X from the options Select your drives as the destination and install Allow time for the drive to format. Verify the drive is mounted on the Desktop. Selecting a different country will clear your cart. Europe, Middle East, Africa. Americas AMER. To do this, you can select your external drive and click on the "Mount" button at the upper menu bar.

If the external hard drive is not mounting in Disk Utility still, reboot your Mac and try again. Another practical solution to this issue is to update the necessary drivers and extensions.

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To update an outdated disk driver, you can simply open your App Store and choose the available one to update. Or if you receive some errors like "System Extension Blocked", it means a disk driver on your Mac is not working due to the lack of an extension, and you can easily enable this extension to be loaded in "Security and Privacy".

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After updating the disk driver or extension, you can reboot your Mac, reconnect the external drive to your Mac, and then remount this drive. The external hard drive shows up in gray but won't mount in Disk Utility, even you have tried to manually mount it? Don't worry, you can check the following solutions and see if they can solve your problem. Step 2: Click Show All Devices in View option and select this external hard drive in the left sidebar.

Step 4: Click Run to check and repair errors in this drive. Suppose First Aid failed on the external hard drive and you still can't open it, your drive is greyed out in Disk Utility because the file system of the drive could be seriously corrupted. Reformatting can fix the file system corruption, but it also will erase all data on it. Therefore, if you didn't back up data before or this external hard drive is used as a Time Machine backup drive, the safe choice is to recover data firstly with reliable data recovery software, like iBoysoft Mac Data Recovery. If data loss is not a hassle for you, you can just skip to reformatting.

This software also can undelete documents, pictures, emails, music, etc. It supports macOS It is possible that an external hard drive is greyed out in Disk Utility, so you try to reformat it by re-partitioning it.

Format Your Drive With Disk Utility

However, the Partition feature is greyed out as well. How to fix this problem?


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Well, you have two options to try. That's to say, you can't perform any input operation to this disk, including re-partition. So have a check if this external disk is Windows NTFS file system by viewing the disk information directly. Well, it's likely that the Partition option is greyed out in Disk Utility because you select the wrong item.

Instead, you should select the disk drive when you want to partition a disk, and the following steps would be helpful. Another problem you might meet in Disk Utility is that you can erase a disk because the Erase option is greyed out. Usually, it happens when you try to erase an internal drive, which is reasonable because you can't erase the startup disk that you are currently running. Then if you want to install a new OS, or if you need to erase personal data before you donate your Mac, how can you erase a system volume?

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Note: Be sure you have an up-to-date backup of your important files and data. But if you lost some important data in this process, you can try iBoysoft Mac Data Recovery to recover your data. However, if your external hard drive is greyed out in Disk Utility, and the disk information and the storage capacity is not even showing up correctly, the disk may die from physical damage.

If this is the case, you can try your luck by sending it to a disk repair service. It will be great if this article has helped you repair the external hard drive that is greyed out in Disk Utility. Vivian likes to share technical tips and solutions with people, especially in macOS and Windows data recovery tricks.


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Being a part of iBoysoft, she has solved many computing and technological problems for readers with ease.