OS X: Why You Need a Hard Drive Clone

If you’re a longtime TMO reader, you may have noticed that most of us are crazy about backups. My personal scheme is, as you might expect, pretty extensive:

  1. My Mac is configured to do hourly Time Machine backups.
  2. I have a continuous offsite backup to CrashPlan (a service I highly recommend).
  3. I plug in an external drive and do a clone every few days.

You may think that’s overkill, but it’s really not. You’d be surprised how often I’ve seen someone’s internal drive fail, only to find that his backup drive had failed as well without him noticing! Ugh. So don’t feel bulletproof just because you own a Time Capsule, all right?

A clone, especially, is an often-overlooked piece of the backup puzzle, as clones are incredibly useful for people who just can’t abide much downtime. If your internal drive stops functioning, a properly configured clone will let you boot off of it and keep working, and your data should look the same as the last time you updated the clone. Depending on what kind of connection your external drive has (and since it’ll probably be a spinning drive rather than an SSD), booting off of a clone could be fairly slow, but hey, it’d be better than having no workable option at all!

So how do you set one up? Well, first you’ll want to procure an external drive (obviously), and you’ll need one that’ll hold all of your existing data. You can find out how much you’re using by visiting the Apple Menu in the upper-left corner of your screen and choosing “About This Mac,” then clicking on the “Storage” tab.

I also recommend leaving a little room when you’re trying to decide how big of a drive to buy. For example, if you’re using 230GB of a 500GB drive, it’d be best to just buy a 500GB external rather than a 250GB one. If you plan on keeping any archives of your files after they’re changed or removed, be sure to account for that as well. 

Anyway, after you have your drive, what software should you use? Plenty of people like SuperDuper, but I prefer Bombich Software’s Carbon Copy Cloner ($39.99). I’ve had great luck with getting in touch with their support when I had questions, and I’ve found CCC itself to be pretty much bulletproof.

This is the CCC icon. I like it, so I included it. I do what I want.

OK, you’ve got the drive. You’ve got the software. What comes next is making sure the new hardware is properly formatted to be able to boot from. Luckily, the aforementioned helpful folks at Bombich Software have provided instructions on how to do just that, and their step-by-step guide walks you through setting up what’s called the GUID Partition Table scheme on your external drive, which sounds complicated but really just means “the way that recent-model Macs organize the disks that they can use to start up from.”

Now when that’s done, what’s left is to configure Carbon Copy Cloner to do your bidding. My favorite thing is to ask CCC to start backing up when both the source (my internal drive) and the destination (my external drive) are connected, meaning that when I plug in my external, the clone starts automatically. 

There are all sorts of options you could choose in CCC if you were so inclined, such as sending yourself an email when errors occur, archiving modified files instead of deleting them from your clone, and so on. But if you’re confused about how to use CCC after you get it, check out Bombich’s extensive knowledge base. I’ve found it to be an invaluable resource. 

Did you make your first clone? Great! Now here comes the big test—boot off of it to be sure it’ll work when you need it to. To do that, follow the instructions from Apple—it’s easy! You’ll want to use the steps under the “Temporarily change your startup disk with Startup Manager” section.

Image source: Apple.

Whew! Do you feel exhausted after all that? Trust me, it’s worth it. Multiple redundant backups mean never having to attempt data recovery yourself on a failed drive, or worse, having to pay someone else to get your stuff back. I’m glad that cleanrooms exist, I really am. I just never want to have to pay anyone to be inside one on my behalf, you know?