146. Restore or Duplicate a Disk  BEFORE YOU BEGIN 145 Verify and Repair a Disk 143 Back Up Your Information
 SEE ALSO 22 Partition a Hard Disk
Using the Disk Utility application, you can quickly and easily make duplicates of entire hard disks or volumes , or restore a hard disk to a known reference "image"a technique commonly used in computer labs and business environments where a network administrator must be able to ensure that multiple computers are all "cloned" from a known software state. Disk Utility can start with either a disk image file or a physical disk (either a hard disk or a CD); you can even specify the URL of a disk image to fetch from an Internet location. The application takes a new disk, initializes it, and then writes the contents of the source disk or disk image onto the new disk. A typical useful application of this technique is if you buy a new disk to replace an aging or deteriorating hard drive; all you have to do is mount the new disk, launch Disk Utility , specify the existing disk as the source and the new disk as the destination, and click Restore . Then you can boot your system using the new disk, and your system will be as good as new!  NOTE You must be logged in as an Admin user to restore or duplicate a disk.
| 1. | Open Disk Utility
First make sure that the disk to which you want to restore is mounted on the Mac. See 21 Add a Newly Installed Hard Disk to the System for more information on adding additional disks.
Navigate into the Utilities folder inside the Applications folder. Double-click the Disk Utility icon to launch the application. Click the Restore tab at the far right of the Disk Utility window to access the Restore functions.
| | 2. | Select a Source Disk or Disk Image Determine which disk you want to use as the source for the restoration process. You can select any disk in the system, including your startup disk if you want to clone it onto a new disk. Drag the disk or volume from the left pane of the Disk Utility window into the Source field to select it. 146. Restore or Duplicate a Disk  TIP To use a disk image file, click the Image button next to the Source field and navigate to where the disk image file is in the navigation pane that appears. | | 3. | Select a Destination Disk You can specify any mounted disk in the system as the destination disk, with the exception of your startup disk and any disk (such as a CD-ROM) that is not writable. Drag a disk or volume from the left pane of the Disk Utility window into the Destination field. TIP If you're particularly concerned about data integrity, you can elect to have Disk Utility do a checksum a mathematical verification of the data writtenafter the disk is restored. This can be done only if you're using a disk image file. Select Scan image for Restore from the Images menu and navigate to the disk image file to prepare the image for restoration with a checksum. If you select the Erase Destination check box at the bottom of the Disk Utility window (which erases all data on the destination disk), you can select or deselect the Skip Checksum check box, which (if selected) saves time by omitting the checksum step, which isn't as necessary if you're erasing the disk. | | 4. | Restore the Disk
When you're ready to copy the source disk to the destination disk, click the Restore button. Disk Utility begins the process of "dubbing" the first disk to the second. The process might take several minutes to an hour or more, depending on the size of the source disk you're using and the speed of your computer.
When the process is complete, you can browse the destination disk and verify that the duplication process took place correctly. You can then remove the disk and install it in another computer, or remove the old disk from your Mac and use the new one if you're moving your data from an old disk to a new one.
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