The volumes or partitions are separate sections of the same parent hard drive created to facilitate data storage in an organized manner. The Disk Utility app in Mac shows the partitions or volumes on your system instead of the complete hard drive.

Erase Mac Hard Drive by Enabling ‘Show All Devices’

If this is the case, follow the methods given below: 1. You’re not able to erase or reformat the hard drive on your Mac when the Erase button turns gray. Methods to Resolve the ‘Disk Utility can’t Erase Mac Hard Drive’ Issue If you find Disk Utility on Mac can’t erase a hard drive, this article will help you resolve the issue. But what to do when Mac Disk Utility can’t erase the hard drive? This may happen due to different reasons. I obviously do not want to erase all data, especially since now it's my only working drive and has files on it I no longer have anywhere else (because the 2tb one will no longer work).The simplest way to erase a Mac hard drive is by using Mac’s native app Disk Utility. Then I went back to time machine and tried to reconnect time machine to the 4tb drive, and get this message: Do you want to erase “Nay Nay External” so it can be used for Time Machine? The volume must be erased because it contains existing data. So I decided to disable the drive from time machine and throw the entire faulty backup folder away (took several tries to successfully delete it from my trash). Except, when I went to the drive and looked for it, it was nowhere to be found except for that same greyed out backup folder. I tried carrying on with using my 4tb as the new backup drive and did a full (successful) time machine back up to it. Because they quit midway through, part of the backups folder transferred over to the 4tb drive but not all, and caused the new 'backups' folder on the 4tb drive to be greyed out and unable to be clicked/opened. After keeping the 4tb one unplugged for a bit, it mounted itself again and I'm able to access the drive - still can't access the 2tb one. Somewhere during the transfer both drives quit, disappeared from my mac, unmounted. So, yesterday I plugged both into a hub with my mac and began copying all time machine files over from one to the other. Well I finished my big projects and wanted to switch the backup drive from the 2tb one to the 4tb one. I have two external HD's - a 4tb one I was using for large projects, and a 2tb one I was using as a backup drive with time machine, as well as backing up the 4tb drive data.

Erase external disk mac