Options for backing up your Mac before installing OS X Yosemite

As we've said before, technology has a habit of failing in novel and unexpected ways at the worst possible moment. For most mainstream Mac users, the halfway point of an operating system update would qualify as such, interrupting their life with at best an unplanned trip to the Apple Store and at worst a costly data recovery invoice.

In our guide to bulletproof backups for your Mac, we recommended a layered backup strategy that combined local, bootable backups with cloud replication to facilitate quick recovery and minimize the risk of data loss.

We stand by that advice and continue to urge you to invest in a robust backup plan, but what if data loss isn't your primary concern? What if you depend on older software packages, and are worried about compatibility?

Well, if you followed our advice and have regular local, bootable backups, you'll be fine —  just make sure to run it again before you click "Install" in the Mac App Store.

You might think that Apple's built-in recovery partition will save you, but it won't. The local recovery system is upgraded alongside the main operating system, so you'll just be reinstalling Yosemite all over again. Internet recovery will install the version of OS X that your computer shipped with, but that's not going to help if you want to keep your files intact.

So what is a person to do?

Step 1: Pick up an external hard drive. External drives are cheap —  just make sure you choose one that is at least the same capacity as the main drive in your Mac. If you have multiple drives —  perhaps you've used an OptiBay to replace your DVD drive with a hard disk —  you only need to worry about the drive on which OS X is installed for the purposes of this guide.

Really any drive from your favorite internet retailer or local big-box store will do, but you shouldn't settle for anything that doesn't come with at least USB 3.0 capability. As long as you're buying an external drive anyway, you might as well plan to use it as part of a long-term backup strategy, and USB 2.0 simply won't do.

Of course, a Thunderbolt drive is ideal if you're on a recent Mac. We recommend LaCie's rugged Thunderbolt and USB 3.0 bus-powered external drive for its speed and portability.

Step 2: Install a backup utility that creates bootable backups. For this purpose, we recommend either Bombich Software's Carbon Copy Cloner or Shirt Pocket Software's SuperDuper!. While the user interfaces are slightly different, both programs will create a file-by-file clone of your boot drive, including operating system files.

The reason we turn to true bootable backups, rather than solutions like Apple's built-in Time Machine, is simple: ease of use. Our goal is to quickly recover the system to a working state if something goes wrong during the upgrade, or if we notice blocking software incompatibility once it's complete.

Step 3: Run a backup. This is the easiest part —  generally, it requires just a couple of clicks. For detailed directions, refer to establishing an initial backup with Carbon Copy Cloner or backup your Macintosh for the first time with SuperDuper!.

Depending on the size of your drive, your first backup should take between 30 minutes and 1 hour. Once it's complete —  assuming it finished without the software alerting you to an error —  you're ready to start installing Yosemite.

Protip: make sure your eject and disconnect your backup drive once the backup is finished.

What do I do if something goes wrong?

If you need to restore your Mac to its backed-up state, the process couldn't be simpler:

1. Connect the external drive containing your bootable backup to your Mac.
2. Reboot the computer, and hold CMD+O during startup.
3. After a few seconds, you'll be asked to choose a startup disk; pick your external drive.
4. Once your Mac is up and running on the external drive, open your cloning software of choice and choose the option to copy files from the external drive to your built-in disk —  the opposite way you did it when creating the backup.
5. When the copying finishes, reboot and hold CMD+O again —  this time, select your newly-restores internal drive.
6. Use your Mac!

What about cloud backup services? We still recommend using services like CrashPlan or Mozy as part of a multi-layered backup strategy. They're suboptimal for our use case, though — you can't restore the operating system itself, and the sheer volume of data can bring your internet connection to its knees.