You can’t reformat a drive in macOS Disk Utility when the Erase button is grayed out. This might happen for a variety of reasons, all of which keep you from erasing or reformatting the drives connected to your Mac.
- Erase Your Hard Drive And Reinstall Macos
- Erase Mac Drive And Reinstall Os Without External Discharge
- Erase Mac Drive And Reinstall Os Without External Disc Drive
- Erase Mac Disk And Reinstall
If your MacBook’s Disk Utility won’t let you erase drives, follow the steps below to fix it.
Jul 02, 2020 If you're erasing an external drive, make sure that it's connected directly to your Mac using a cable that you know is good. Then turn the drive off and back on. If your disk or volume still doesn't appear in Disk Utility, or Disk Utility reports that the erase process failed, your disk or Mac. Installing the Mac operating system on an external drive is the safest way to get a good look at a new OS without changing anything on your Mac. It'll leave your current configuration intact. Jul 30, 2017 Click on the Erase tab in Disk Utility's main window. A panel will drop down. Set the partition scheme to GUID. Set the Format type to Mac OS Extended (Journaled.) Click on the Apply button, then click on the Done button when it activates. Quit Disk Utility and return to the Utility Menu. Select Reinstall OS X and click on the Continue button.
Contents
- 2 What if the Erase Button in Disk Utility is grayed Out?
- 3 Learn how to reinstall macOS after erasing your Drive
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How to erase or reformat a Drive using Disk Utility
Let’s start with a brief explanation of the correct way to reformat or erase drives using your Mac. Feel free to skip this section if you already know how to do it.
You may want to erase your drive as a quick way to create space for new files. Or you might need to reformat it so it works with different operating systems, like Windows, Linux, or even iPadOS.
When you reformat a drive, it also erases all the data on it. Canon mp640 scanner. So make sure to back up any important files before erasing or reformatting your drives.
When you’re ready, here’s how to erase or reformat drives:
- Open Disk Utility from the Utilities folder in your Applications.
- In the sidebar, select the drive you want to erase or reformat.
- Click the Erase button at the top of the window.
- Choose a new name and format for your drive, then click Erase.
- Wait for Disk Utility to erase or reformat your drive, then click Done.
What if the Erase Button in Disk Utility is grayed Out?
You’re probably reading this article because the Erase button was grayed out when you tried to erase or reformat a drive using Disk Utility. Use the steps below to fix it and let us know in the comments which one worked for you.
Step 1. Show All Devices and Erase the Parent Drive
By default, Disk Utility only shows the Volumes on your connected drives, rather than the drives themselves. A Volume is the partition or section of a drive you store data in.
Open Disk Utility and select View > Show All Devices from the menu bar. You should see the device names for each of your drives appear in the sidebar.
Select the parent folder for the drive you want to reformat or erase, then click the Erase button again. Take note that when you erase a device, it erases all the Volumes contained within it as well.
Step 2. Run First Aid to Repair Your Drive Before Erasing It
Disk Utility has a First Aid feature that fixes all kinds of issues related to your drives: slow performance, corrupt files, or unexpected behavior. When you run First Aid, it scans the entire disk for errors and lets you know if there are any it can’t repair.
Open Disk Utility and select the drive you want to erase from the sidebar. At the top of the window, click the First Aid button, then agree to Run First Aid.
The length of time First Aid takes to run depends on the size of your drive, how much data is on it, and how many errors need fixing.
Combine this step with the previous one to run First Aid on the parent device for your drive, as well as the individual Volumes.
Step 3. Boot Into Recovery Mode to Erase Your Startup Disk
If you’re trying to reformat or erase the startup disk on your Mac, you need to boot into Recovery Mode first. The startup disk is the main hard drive on your computer: the one that stores macOS and all your data. It’s not usually possible to erase the startup disk because your Mac is using it to run macOS.
Recovery Mode is a special partition on your Mac you can use to restore from a backup, reinstall macOS, get online support, or erase your startup disk.
You should back up your Mac before trying to erase or reformat it.
When you’re ready to boot into Recovery Mode, restart your Mac and hold Cmd + R while it boots up. Keep holding both keys until you see an Apple logo or hear a startup sound.
You should see a macOS Utilities window appear. Select Disk Utility from this window and try erasing or reformatting your drive again.
Learn how to reinstall macOS after erasing your Drive
After erasing or reformatting the startup disk—if that was your goal—you need to reinstall macOS before you can use your Mac again. This is because the original macOS installation was on the startup disk you just erased.
Boot into Recovery Mode once more to reinstall macOS or follow our guide to factory reset any Mac. When you reinstall macOS, your Mac behaves as though it’s a brand new machine, with no data on it waiting for you to set it up.
Dan is a freelance writer based in South West England.
He spent two years supervising repairs as a Genius Admin for Apple Retail and uses that knowledge to keep our troubleshooting guides up to date.
Erase Your Hard Drive And Reinstall Macos
Long before that, Dan turned to Apple products from a musical background. Having owned iPods for years, he bought a MacBook to learn sound recording and production. It was using those skills that he gained a first-class Bachelor of Science in Sound Technology.
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Looking for a way to install and run OS X on an external hard drive? This can be useful for a couple of different reasons. Firstly, it allows you to run another copy of OS X without needing any additional Mac computer.
Also, since you can run a full copy of OS X on the external drive, it can be used for troubleshooting purposes on other Macs or it can be as a kind of virtual OS X. I’ve already written about how you can install OS X in VMware Fusion, but that takes up space on your Mac. Using an external drive, you can save space on your Mac, though it might be a bit slower if you are using USB 2.0.
In this article, I’ll walk you through the requirements and steps to install OS X onto an external hard drive.
Format External Hard Disk
The first thing you’re going to need to do is format the external hard drive properly. The file format has to be Mac OS X Journaled and you have to use the GUID partition map. To do this, open Disk Utility and connect the drive to your Mac.
![Erase mac drive and reinstall os without external discharge Erase mac drive and reinstall os without external discharge](https://www.easeus.com/images/en/screenshot/data-recovery-mac/mac-external-hard-drive-read-only-formatting.png)
Under External in the left hand menu, click on your external hard drive and then click on the Erase button. Make sure you backup any data before you erase the drive. When you click Erase, a dialog will pop up where you can configure some options.
Erase Mac Drive And Reinstall Os Without External Discharge
Give your drive a name, choose OS X Extended (Journaled) for Format and GUID Partition Map for Scheme. It should only take a minute or two for the drive to be erased and reformatted. Now your drive is ready for OS X.
Install OS X
There are two ways you can install OS X on to your external hard disk: by reinstalling OS X from the OS X Utilities repair screen or by downloading OS X from the App Store and running the installer. I’ll show you both methods in case one isn’t working for you.
The easiest way is to download OS X from the App Store. Once you open the App Store, you’ll see a link on the right for the latest version of OS X (El Capitan as of this writing).
![Erase Mac Drive And Reinstall Os Without External Disc Erase Mac Drive And Reinstall Os Without External Disc](/uploads/1/2/7/0/127088096/116085449.jpg)
Go ahead and click the Download button to start downloading the installer. Note that if you already have that version of OS X installed, you’ll see a popup message appear asking if you still want to continue or not. Just click Continue.
Once it has been downloaded, just double-click the installer, which will be located in the Applications folder.
Keep clicking past the license agreement, etc., until you get to the screen that asks you which disk to install OS X on. By default, it is set to MacBook.
Click on the Show All Disks button and you’ll see an icon for the different disks and partitions on the Mac. I named my external hard drive OS X and that shows up in the middle.
You can also tell it’s an external hard disk because it uses the icon with the orange hard drive. Click Continue and then follow the instructions to complete the installation. Note that your computer may restart during the install and you don’t have to do anything. OS X will automatically continue installing onto the external hard drive rather than booting up to your internal version of OS X.
At the end of this article, I’ll show you how to boot up to the external hard drive, so skip down if you ended up using the App Store method. Note that by default, the Mac will start booting up directly to the external hard drive until you change it.
The second method to install OS X is to restart the Mac and press and hold the COMMAND + R keys. This will load up OS X Recovery.
The OS X Utilities screen will appear and here you want to click on Reinstall OS X. Again, you’ll go through some basic screens, but when you get to the hard disk screen, click on Show All Disks again.
Using this method, you’ll have to login using your Apple ID and password so that the entire OS X installer can be downloaded off of Apple’s servers. Whichever method you choose, it will take anywhere from 15 to 30+ minutes to install OS X onto your external hard drive.
While OS X is installing, your computer will restart a couple of times. Note that when it finally boots into OS X, that is the version running off your external drive. To switch back and forth between the internal and external drive, you have to restart your computer and hold down the OPTION key.
Erase Mac Drive And Reinstall Os Without External Disc Drive
When you do that, you should see at least four icons. In my case, I have five because I have Windows installed using Boot Camp. Anyway, the grey MacBook and Recovery 10.11.2 icons are for my internal OS X and the orange OS X and Recovery 10.11.3 are for the version installed on my external drive.
Erase Mac Disk And Reinstall
Use the arrow keys to select which drive to boot from and then simply press Enter. If you have a newer Mac and a USB drive that supports USB 3.0, everything should run fairly fast. Overall, it’s a fairly straight-forward process and took me less than an hour to get everything working. If you have any questions, feel free to comment. Enjoy!