In the Time Machine settings menu, click the 'select backup disk' button. Select your external drive from the menu, then click 'use disk' to confirm it as your Time Machine backup drive. To see the size of a specific file or folder, click it once and then press Command-I. To see storage information about your Mac, click the Apple menu in the top-left of your screen. Choose About This Mac and click the Storage tab. For Time Machine backups, it's good to use a drive that has at least twice the storage capacity of your Mac.
Disk Utility User Guide
- The simplest solution is to put an external USB drive or SD card into service using the OS X Recovery Disk Assistant. To create a recovery disk, you need a USB flash drive or an external hard drive.
- Mar 31, 2020 Apple's built-in backup program for the Mac, Time Machine, makes it incredibly easy to back up all of your important data so you can restore your computer if something should happen. You can even recover deleted files if you accidentally lose them.
- Apr 14, 2015 The simplest solution is to put an external USB drive or SD card into service using the OS X Recovery Disk Assistant. To create a recovery disk, you need a USB flash drive or an external hard drive.
You can use Disk Utility to create a disk image, which is a file that contains other files and folders.
Note: You can burn information to a CD or DVD using the Burn command in the Finder. See Burn CDs and DVDs.
Create a blank disk image for storage
You can create an empty disk image, add data to it, then use it to create disks, CDs, or DVDs.
In the Disk Utility app on your Mac, choose File > New Image > Blank Image.
Enter a filename for the disk image, add tags if necessary, then choose where to save it.
This is the name that appears in the Finder, where you save the disk image file before opening it.
In the Name field, enter the name for the disk image.
This is the name that appears on your desktop and in the Finder sidebar, after you open the disk image.
In the Size field, enter a size for the disk image.
Click the Format pop-up menu, then choose the format for the disk:
If the disk image will be used with a Mac that has a solid state drive (SSD) and uses macOS 10.13 or later, choose APFS or APFS (Case-sensitive).
If the disk image will be used with a Mac with macOS 10.12 or earlier, choose Mac OS Extended (Journaled) or Mac OS Extended (Case-sensitive, Journaled).
If the disk image will be used with a Mac or Windows computer and is 32 GB or less, choose MS-DOS (FAT); if it's over 32 GB, choose ExFAT.
To encrypt the disk image, click the Encryption pop-up menu, then choose an encryption option.
Click the Partitions pop-up menu, then choose a partition layout.
Click the Image Format pop-up menu, then choose an option:
Sparse bundle disk image: Same as a sparse disk image (below), but the directory data for the image is stored differently. Uses the .sparsebundle file extension.
Sparse disk image: Creates an expandable file that shrinks and grows as needed. No additional space is used. Uses the .sparseimage file extension.
Read/write disk image: Allows you to add files to the disk image after it's created. Uses the .dmg file extension.
DVD/CD master: Changes the size of the image to 177 MB (CD 8 cm). Uses the .cdr file extension.
Click Save, then click Done.
Disk Utility creates the disk image file where you saved it in the Finder and mounts its disk icon on your desktop and in the Finder sidebar.
In the Finder, copy your files to the mounted disk image, then eject it.
Restore the disk image to a disk.
For more information about disk image types, see the manual (man) page for hdiutil.
Create a disk image from a disk or connected device
You can create a disk image that includes the data and free space on a physical disk or connected device, such as a USB device. For example, if a USB device or volume is 80 GB with 10 GB of data, the disk image will be 80 GB in size and include data and free space. You can then restore that disk image to another volume.
In the Disk Utility app on your Mac, select a disk, volume, or connected device in the sidebar.
Choose File > New Image, then choose 'Image from [device name].'
Enter a filename for the disk image, add tags if necessary, then choose where to save it.
This is the name that appears in the Finder, where you save the disk image file before opening it.
Click the Format pop-up menu, then choose an option:
Read-only: The disk image can't be written to, and is quicker to create and open.
Compressed: Compresses data, so the disk image is smaller than the original data. The disk image is read-only.
Read/write: Allows you to add files to the disk image after it's created.
DVD/CD master: Can be used with third-party apps. It includes a copy of all sectors of the disk image, whether they're used or not. When you use a master disk image to create other DVDs or CDs, all data is copied exactly.
To encrypt the disk image, click the Encryption pop-up menu, then choose an encryption option.
Click Save, then click Done.
Disk Utility creates the disk image file where you saved it in the Finder and mounts its disk icon on your desktop and in the Finder sidebar.
Important: Don't create a disk image of a disk that you believe to be failing or that contains corrupted information. The disk image may not serve as a reliable backup.
For technical information about creating a restore disk image, see the Apple Software Restore (ASR) manual (man) page.
Create a disk image from a folder or connected device
You can create a disk image that contains the contents of a folder or connected device, such as a USB device. This method doesn't copy a device's free space to the disk image. For example, if a USB device or volume is 80 GB with 10 GB of data, the disk image will be 10 GB in size and include only data, not free space. You can then restore that disk image to another volume.
In the Disk Utility app on your Mac, choose File > New Image, then choose Image from Folder.
Select the folder or connected device in the dialog that appears, then click Open.
Enter a filename for the disk image, add tags if necessary, then choose where to save it.
This is the name that appears in the Finder, where you save the disk image file before opening it.
To encrypt the disk image, click the Encryption pop-up menu, then choose an encryption option.
Click the Image Format pop-up menu, then choose an option:
Read-only: The disk image can't be written to, and is quicker to create and open.
Compressed: Compresses data, so the disk image is smaller than the original data. The disk image is read-only.
Read/write: Allows you to add files to the disk image after it's created.
DVD/CD master: Can be used with third-party apps. It includes a copy of all sectors of the disk image, whether they're used or not. When you use a master disk image to create other DVDs or CDs, all data is copied exactly.
Hybrid image (HFS+/ISO/UDF): This disk image is a combination of disk image formats and can be used with different file system standards, such as HFS, ISO, and UDF.
Click Save, then click Done.
Disk Utility creates the disk image file where you saved it in the Finder and mounts its disk icon on your desktop and in the Finder sidebar.
For technical information about creating a restore disk image, see the Apple Software Restore (ASR) manual (man) page.
Create a secure disk image
If you have confidential documents that you don't want others to see without your permission, you can put them in an encrypted disk image.
Note: If you want to protect the contents of the system disk, turn on FileVault using the FileVault pane of Security & Privacy Preferences.
In the Disk Utility app on your Mac, choose File > New Image > Blank Image.
Enter a filename for the disk image, add tags if necessary, then choose where to save it.
This is the name that appears in the Finder, where you save the disk image file before opening it.
In the Name field, enter the name for the disk image.
This is the name that appears on your desktop and in the Finder sidebar, after you open the disk image.
In the Size field, enter a size for the disk image.
Click the Format pop-up menu, then choose a format:
If you're using the encrypted disk image with a Mac computer using macOS 10.13 or later, choose APFS or APFS (Case-sensitive).
If you're using the encrypted disk image with a Mac computer using macOS 10.12 or earlier, choose Mac OS Extended (Journaled) or Mac OS Extended (Case-sensitive, Journaled).
Click the Encryption pop-up menu, then choose an encryption option.
Enter and re-enter a password to unlock the disk image, then click Choose.
WARNING: If you forget this password, you won't be able to open the disk image and view any of the files.
Use the default settings for the rest of the options:
Click the Partitions pop-up menu, then choose Single partition - GUID Partition Map.
Click the Image Format pop-up menu, then choose 'read/write' disk image.
Click Save, then click Done.
Disk Utility creates the disk image file where you saved it in the Finder and mounts its disk icon on your desktop and in the Finder sidebar.
In the Finder , copy the documents you want to protect to the disk image.
If you want to erase the original documents so they can't be recovered, drag them to the Trash, then choose Finder > 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 available on your desktop, anyone with access to your computer can use the documents on it.
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 as you would with a disk.
Disk Utility can find and repair errors related to the formatting and directory structure of a Mac disk. Errors can lead to unexpected behavior when using your Mac, and significant errors might even prevent your Mac from starting up completely.
Mac Os X Backup Utility
Before proceeding, make sure that you have a current backup of your Mac, in case you need to recover damaged files or Disk Utility finds errors that it can't repair.
Open Disk Utility
In general, you can just open Disk Utility from the Utilities folder of your Applications folder. However, if your Mac doesn't start up all the way, or you want to repair the disk your Mac starts up from, open Disk Utility from macOS Recovery:
- Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:
- Apple silicon: Turn on your Mac and continue to press and hold the power button until you see the startup options window. Click the gear icon labeled Options, then click Continue.
- Intel processor: Turn on your Mac, then immediately press and hold these two keys until you see an Apple logo or other image: Command (⌘) and R.
- You may be asked to select a user you know the password for. Select the user, then click Next and enter their administrator password.
- From the utilities window in macOS Recovery, select Disk Utility and click Continue.
Mac Os X Disk Cleanup
Select your disk in Disk Utility
Choose View > Show All Devices (if available) from the menu bar or toolbar in Disk Utility.
The sidebar in Disk Utility should now show each available disk or other storage device, beginning with your startup disk. And beneath each disk you should see any containers and volumes on that disk. Don't see your disk?
In this example, the startup disk (APPLE HDD) has one container and two volumes (Macintosh HD, Macintosh HD - Data). Your disk might not have a container, and it might have a different number of volumes.
Repair volumes, then containers, then disks
For each disk that you're repairing, start by selecting the last volume on that disk, then click the First Aid button or tab.
In this example, the last volume on the disk is Macintosh HD - Data.
Click Run to begin checking the selected volume for errors.
- If there is no Run button, click the Repair Disk button instead.
- If the button is dimmed and you can't click it, skip this step for the disk, container, or volume you selected.
- If you're asked for a password to unlock the disk, enter your administrator password.
After Disk Utility is done checking the volume, select the next item above it in the sidebar, then run First Aid again. Keep moving up the list, running First Aid for each volume on the disk, then each container on the disk, then finally the disk itself.
In this example, the repair order is Macintosh HD - Data, then Macintosh HD, then Container disk3, then APPLE HDD.
Format Disk Mac Os X
If Disk Utility found errors that it can't repair
If Disk Utility found errors that it could not repair, use Disk Utility to erase (format) your disk.
If your disk doesn't appear in Disk Utility
If Disk Utility can't see your disk, it also can't see any containers or volumes on that disk. In that case, follow these steps:
Backup Disk Mac Os X 10.13
- Shut down your Mac, then unplug all nonessential devices from your Mac.
- If you're repairing 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 still doesn't appear in Disk Utility, your Mac might need service. If you need help, please contact Apple Support.
