Symbolic links (Unix-based file references that function like Mac aliases) must be recreated correctly. Every file on your drive-including thousands of hidden files-must be copied just so, with permissions and other metadata intact. Unfortunately, you can’t make a clone merely by copying files from your startup volume to an external drive in the Finder. OS X Recovery features include Disk Utility, but sometimes you need a drive-repair app with more oomph.) Finally, having a clone is essential when upgrading to a new version of OS X, because it gives you the option to easily revert to your previous system (by erasing your upgraded-OS drive and then restoring from the clone) if compatibility problems arise. By contrast, even though Time Machine also backs up every file on your drive, restoring all those files to a new drive takes hours (or possibly days) restoring an entire drive from an online backup service takes even longer.Ī clone also comes in handy for troubleshooting, because you can use it to run third-party utilities on your ailing drive.

A few moments later, you’re back up and running-and you can then repair (or replace) your main startup drive more or less at your leisure. You simply attach your clone drive, restart while holding down the Option key, select the clone drive in OS X’s Startup Manager, and press Return. What a clone offers that the likes of Time Machine and CrashPlan do not is immediate recovery: You can get back to work almost instantly after a drive crash or other severe problem with your startup volume.

Clone macos to external drive