Download the Catalina update; Prepare USB Thumb Drive. Connect 8GB USB 3.0 drive; Open Disk Utility, choose USB drive from the left pane and click ‘Erase’ Choose Mac OS Extended (Journaled) and GUID Partition Map and click ‘Erase’ The USB drive is now ready to become a macOS Catalina Installer. Format external hard drive for macOS. Backing up a Mac with Time Machine requires an external hard drive formatted for macOS. Formatting the drive will erase everything on it and configure it for macOS. After formatting the drive, if prompted to back up with Time Machine, select Use as Backup Disk. This will open the Time Machine preferences. Connect the empty external hard drive or SSD Format the drive to APFS with GUID Partition table. Please make sure it doesn’t contain any data as it will be permanently lost Click ‘ Erase ’ and then exit Disk Utility.

Erasing your disk: For most reasons to erase, including when reformatting a disk or selling, giving away, or trading in your Mac, you should erase your entire disk.

Erasing a volume on your disk: In other cases, such as when your disk contains multiple volumes (or partitions) and you don't want to erase them all, you can erase specific volumes on the disk.

Erasing a disk or volume permanently deletes all of its files. /macos-create-alias-for-visual-studio-code.html. Before continuing, make sure that you have a backup of any files that you want to keep.

How to erase your disk

Format
  1. Start up from macOS Recovery. Then select Disk Utility from the Utilities window and click Continue.
    If you're not erasing the disk your Mac started up from, you don't need to start up from macOS Recovery: just open Disk Utility from the Utilities folder of your Applications folder.
  2. Choose View > Show All Devices from the menu bar in Disk Utility. The sidebar now shows your disks (devices) and any containers and volumes within them. The disk your Mac started up from is at the top of the list. In this example, Apple SSD is the startup disk:
  3. Select the disk that you want to erase. Don't see your disk?
  4. Click Erase, then complete these items:
    • Name: Type the name that you want the disk to have after you erase it.
    • Format: Choose APFS or Mac OS Extended (Journaled). Disk Utility shows a compatible format by default.
    • Scheme: Choose GUID Partition Map.
  5. Click Erase to begin erasing your disk and every container and volume within it. You might be asked to enter your Apple ID. Forgot your Apple ID?
  6. When done, quit Disk Utility.
  7. If you want your Mac to be able to start up from the disk you erased, reinstall macOS on the disk.

How to erase a volume on your disk

  1. Start up from macOS Recovery. Then select Disk Utility from the Utilities window and click Continue.
    If you're not erasing the volume your Mac started up from, you don't need to start up from macOS Recovery: just open Disk Utility from the Utilities folder of your Applications folder.
  2. In the sidebar of Disk Utility, select the volume that you want to erase. The volume your Mac started up from is named Macintosh HD, unless you changed its name. Don't see your volume?
  3. Click Erase, then complete these items:
    • Name: Type the name that you want the volume to have after you erase it.
    • Format: Choose APFS or Mac OS Extended (Journaled). Disk Utility shows a compatible format by default.
  4. If you see an Erase Volume Group button, the volume you selected is part of a volume group. In that case, you should erase the volume group. Otherwise, click Erase to erase just the selected volume. You might be asked to enter your Apple ID. Forgot your Apple ID?
  5. When done, quit Disk Utility.
  6. If you want your Mac to be able to start up from the volume you erased, reinstall macOS on that volume.

Reasons to erase

You can erase at any time, including in circumstances such as these:

  • You want to permanently erase all content from your Mac and restore it to factory settings. This is one of the final steps before selling, giving away, or trading in your Mac.
  • You're changing the format of a disk, such as from a PC format (FAT, ExFAT, or NTFS) to a Mac format (APFS or Mac OS Extended).
  • You received a message that your disk isn't readable by this computer.
  • You're trying to resolve a disk issue that Disk Utility can't repair.
  • The macOS installer doesn't see your disk or can't install on it. For example, the installer might say that your disk isn't formatted correctly, isn't using a GUID partition scheme, contains a newer version of the operating system, or can't be used to start up your computer.
  • The macOS installer says that you may not install to this volume because it is part of an Apple RAID.

About APFS and Mac OS Extended

Disk Utility in macOS High Sierra or later can erase using either the newer APFS (Apple File System) format or the older Mac OS Extended format, and it automatically chooses a compatible format for you.

How to choose between APFS and Mac OS Extended

Disk Utility tries to detect the type of storage and show the appropriate format in the Format menu. If it can't, it chooses Mac OS Extended, which works with all versions of macOS. If you want to change the format, answer these questions:

  • Are you formatting the disk that came built into your Mac?
    If the built-in disk came APFS-formatted, Disk Utility suggests APFS. Don't change it to Mac OS Extended.
  • Are you about to install macOS High Sierra or later for the first time on the disk?
    If you need to erase your disk before installing High Sierra or later for the first time on that disk, choose Mac OS Extended (Journaled). During installation, the macOS installer decides whether to automatically convert to APFS—without erasing your files.
  • Are you preparing a Time Machine backup disk or bootable installer?
    Choose Mac OS Extended (Journaled) for any disk that you plan to use as a Time Machine backup disk or as a bootable installer.
  • Will you be using the disk with another Mac?
    If the other Mac isn't using macOS High Sierra or later, choose Mac OS Extended (Journaled). Earlier versions of macOS don't work with APFS-formatted volumes.

How to identify the format currently in use

If you want to know which format is currently in use, use any of these methods:

  • Select the volume in the Disk Utility sidebar, then check the information shown on the right. For more detail, choose File > Get Info from the Disk Utility menu bar.
  • Open System Information and select Storage in the sidebar. The File System column on the right shows the format of each volume.
  • Select the volume in the Finder, then choose File > Get Info from the menu bar. The Get Info window shows the Format of that volume.

If your disk or volume doesn't appear, or the erase fails

  1. Shut down your Mac, then unplug all nonessential devices from your Mac.
  2. 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.
  3. 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 might need service. If you need help, please contact Apple Support.

Learn more

  • If you can't start up from macOS Recovery, you can use a different startup disk instead.
  • If Disk Utility shows a Security Options button in the Erase window, you can click that button to choose between a faster (but less secure) erase and a slower (but more secure) erase. Some older versions of Disk Utility offer the option to zero all data instead. These secure-erase options aren't offered or needed for solid-state drives (SSDs) and flash storage.

Mac Os Format External Drive

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Disk Utility User Guide

In Disk Utility on Mac, you can erase and reformat storage devices to use with your Mac. Erasing a storage device deletes everything on it.

  1. If you have any files you want to save, copy them to another storage device.

  2. Open the Disk Utility app on your Mac using one of the following methods, depending on the type of disk or volume you want to erase:

    • If you want to erase your startup disk or startup volume: Start up from macOS Recovery, then choose Disk Utility from the macOS Utilities window.

    • If you want to erase any other type of disk or volume: Double-click Disk Utility in the /Applications/Utilities folder.

  3. Choose View > Show All Devices.

  4. In the sidebar, select the storage device you want to erase, then click the Erase button .

  5. Click the Scheme pop-up menu, then choose GUID Partition Map.

  6. Click the Format pop-up menu, then choose a choose a file system format.

  7. Enter a name.

  8. (Optional) If available, click Security Options, use the slider to choose how many times to write over the erased data, then click OK.

    /top-macos-apps-for-it.html. Secure erase options are available only for some types of storage devices. If the Security Options button is not available, Disk Utility cannot perform a secure erase on the storage device.

    Writing over the data three times meets the U.S. Department of Energy standard for securely erasing magnetic media. Writing over the data seven times meets the U.S. Department of Defense 5220-22-M standard.

  9. Click Erase, then click Done.

Note: With a solid-state drive (SSD), secure erase options are not available in Disk Utility. For more security, consider turning on FileVault encryption when you start using your SSD drive.

Format External Hard Drive For Mac

See alsoApple Support article: How to erase a disk for MacPartition a physical disk in Disk Utility on MacFile system formats available in Disk Utility on MacFormat a disk for Windows computers in Disk Utility on MacEncrypt and protect a storage device with a password in Disk Utility on Mac