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Disk Utility 12.x: Create a disk image

Create a disk image using Disk Utility

You can use Disk Utility to create a disk image, which is a file that looks and functions like a disk: It contains other files and folders, and appears with a disk icon on your desktop when you open it. You can use a disk image to archive old data, share files with others, encrypt sensitive information, and make copies of disks.

To access the data in a disk image, double-click it. It appears on your desktop, and you can add, remove, and edit files on it just like you would with a disk.

Archive files in a disk image

You can archive files in a disk image and then burn the disk image to a CD or DVD, save it to a disk, or send it to other Mac users. If you are archiving confidential information, you can encrypt it.

Note: If you want to create an archive that users with Windows and other types of computers can open, don’t use Disk Utility; select the items to archive in the Finder and choose File > Create Archive.
  1. Move all the files to archive into the same folder.
  2. Open Disk Utility, in the Utilities folder in Launchpad.
  3. Choose File > New > “Disk Image from Folder.”
  4. Choose the folder you want, and click Image.
  5. Type a name for the disk image, and select where to save it.
  6. Choose an option from the Image Format pop-up menu:
    • Choose “compressed” to create a smaller disk image.

    • Choose “read-only” to create disk image that’s quicker to create and open.

  7. To encrypt the disk image, choose an encryption option from the Encryption pop-up menu.
  8. Click Save.

    If you chose to encrypt the disk image, enter a password in the dialog that appears.

Protect confidential documents in a secure disk image

If you have confidential documents that you don’t want to be viewed by others without your permission, you can put them in an encrypted disk image.

Note: If you want to protect the contents of your entire home directory, turn on FileVault using the Security pane of System Preferences.
  1. Open Disk Utility, in the Utilities folder in Launchpad.
  2. Choose File > New > Blank Disk Image.
  3. Type a name for the image, and choose where you want to save it.
  4. In the Name field, type a name for the disk that appears when you open the disk image.

    The disk and the disk image can have the same name.

  5. Choose the size of the disk image from the Size pop-up menu.

    Be sure you choose a size that’s large enough to hold any changes and new documents you might add.

  6. Choose an encryption option from the Encryption pop-up menu.
  7. Use the default settings for the rest of the options:
    • Choose Mac OS Extended (Journaled) from the Format pop-up menu.

    • Choose “Single partition - Apple Partition Map” from the Partitions pop-up menu.

    • Choose “read/write disk image” from the Image Format pop-up menu.

  8. Click Save.
  9. Enter a password, deselect “Remember password in my keychain,” and then click OK.

    Disk Utility creates the disk image and mounts its disk on your desktop.

    If you select “Remember password in my keychain,” anyone with access to your computer may be able to open the disk image without entering the password.

  10. Copy to the disk the documents you want to protect.
  11. If you want to erase the original documents so they can’t be recovered, drag them to the Trash, and choose Finder > Secure Empty Trash.

When you’re finished using the documents on the secure disk image, be sure to eject the disk image. As long as it’s mounted on your desktop, anyone with access to your computer can use the documents on it.

Create a disk image from a disk or folder

You can create a disk image that contains the contents of a folder or disk and then restore that disk image to another disk or burn it to a CD or DVD.

For example, you can back up the files on your disk by creating a disk image from it and then copying the image to another disk or burning it on a CD or DVD for safekeeping.

You can also use a disk image to restore software on several computers. For example, if you administer a lab of computers, you can create a disk image to regularly restore each computer to its original state.

  1. Open Disk Utility, in the Utilities folder in Launchpad.
  2. Choose File > New, and then choose either “Disk Image from Folder” or “Disk Image from [disk name].”
  3. If you are creating a disk image from a folder, select it in the dialog that appears, and click Image.
  4. Type a name for the disk image, and choose where you want to save it.
  5. Choose an option from the Image Format pop-up menu.
    • Choose "compressed" to create a smaller disk image.

    • Choose "read-only" to create a disk image that's quicker to create and open.

  6. To require a password to access the contents of the disk image, choose an option from the Encryption pop-up menu.
  7. Click Save.

For technical information about creating a restore disk image, see the Apple Software Restore (ASR) manual (man) page.

Create a disk image to burn

You can create an empty disk image, fill it with data, and use it to create disks, CDs, or DVDs. The disks you create can be formatted for Mac, Windows, and other types of computers. They don’t need to use the same format as your disk.

  1. Open Disk Utility, in the Utilities folder in Launchpad.
  2. Choose File > New > Blank Disk Image.
  3. Type a name for the disk image, and choose where you want to save it.
  4. In the Name field, enter the name for the disk that appears when you open the disk image.
  5. Choose the size of the disk image from the Size pop-up menu.
  6. Choose the format for the disk from the Format pop-up menu:
    • If the disk will be used with Mac computers, choose Mac OS Extended (Journaled).

    • If the disk will be used with Windows or Mac computers and is 32 GB or under, choose MS-DOS (FAT).

    • If the disk will be used with Windows or Mac computers and is over 32 GB, choose ExFAT.

  7. To require a password to use the disk image, choose an encryption option from the Encryption pop-up menu.
  8. From the Partitions pop-up menu, choose the partition scheme that best matches the type of disk you create.
  9. Choose “read/write disk image” from the Image Format pop-up menu.
  10. Click Create.

    Disk Utility creates the disk image and mounts its disk on your desktop.

  11. In the Finder, copy your files to the disk, and then eject it.
  12. Restore the disk image to a disk, or burn it to a CD or DVD.

    Restore a disk image to a disk

    Burn a disk image to a CD or DVD

Create a blank disk image for storage

You can create a blank disk image to store files. Normally, you need to gather all the files you want to be included into a single location before you create a disk image. However, with a blank disk image, you can add files to the image at any time.

  1. Open Disk Utility, in the Utilities folder in Launchpad.
  2. Choose File > New > Blank Disk Image.
  3. Type a name for the disk image, and then choose where you want to save it from the pop-up menu.
  4. In the Name field, enter the name for the disk that appears when you open the disk image.
  5. Choose the size of the disk image from the Size pop-up menu.
  6. To require a password to open the disk image, choose an encryption option from the Encryption pop-up menu.
  7. Choose “Single partition - Apple Partition Map” from the Partitions pop-up menu.
  8. Choose “sparse bundle disk image” from the Image Format pop-up menu.
  9. Click Create.

To add files to the disk image, open the disk image in the Finder, and then drag files to its icon on the desktop.

Last Modified: Jul 11, 2012
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  • Last Modified: Jul 11, 2012
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