Information Technology Reference
Test Your Duplicate
After you've made your first bootable duplicate, be sure to verify that
you can indeed start your Mac from it. To do this, follow these steps:
1. Restart your Mac by choosing Apple > Restart and clicking
Restart when prompted.
Be aware that since you're going to be switching to a different
startup drive, deselecting the “Reopen windows when logging
back in” checkbox may not have the desired effect—windows
and apps may still reopen when your Mac finishes booting. If you
want to avoid that, instead open the Startup Disk pane of System
Preferences, select your duplicate, and perform a safe boot—see
the sidebar Perform a Safe Boot for details.
2. As soon as the startup chime plays, press and hold the Option key.
3. When your screen shows the volumes available for booting your
computer, use the arrow keys to select your duplicate and press
Return. Your Mac should boot from the duplicate—but be aware
that this may take considerably longer than booting from your
regular startup disk.
4. To verify that your Mac has indeed started from the duplicate and
not from your regular startup disk, choose Apple > About This
Mac. The name of the current startup disk appears next to the label
“Startup Disk.” (You did give your duplicate a different name from
your regular startup disk, right?)
5. If you selected your duplicate as your startup disk in Step 1, repeat
the process to select your regular startup disk.
6. Choose Apple > Restart (without pressing any keys this time) to
start from your internal disk again.
If your Mac fails to start from the duplicate, verify that the drive's
partition map scheme and format are correct (see Prepare Your Hard
Drive ) and try creating the duplicate again.