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Synopsis:

Learn how to use Time Machine to make multiple backups of your machine so that offsite copies can be maintained and updated as needed.

Let's Begin:

Time Machine is a great way to make quick and easy backups of your Mac. But what if you want to have an offsite backup in addition to your onsite backup? Turns out this is trivially easy to do. You just need an extra hard drive in an external enclosure.

The key to making this work is already built into the way Time Machine works. Time Machine saves all the information about the backups it makes on the volume you’re using for the backup. This means that you can have as many different backup volumes as you want and your Mac will keep everything straight for each one since each is basically a self contained unit.

Here’s how to set this up:

Let’s say you already have Time Machine backing up your Mac to external hard drive and let’s say this volume is called “Backup 1”. To make a second backup to take offsite, just unmount “Backup 1” and disconnect the drive from your Mac. Next plug in your new hard drive and initialize it if need be. Let’s name this volume “Backup 2” so we know which is which. Once this new drive is initialized and mounted, just head over to the Time Machine Preferences pane and point it at this new drive by clicking where it says “Select Disk”. Shortly after you do this, Time Machine will begin a backup (usually within two minutes). Since the new backup disk is empty at this point, Time Machine will automatically perform a full backup of your system, so this may take a little while. When the backup is complete, you can unmount this volume (“Backup 2”) and store it safely offsite. You can then plug your original Time Machine backup volume (“Backup 1”) back in, select it for backups in the Time Machine Preferences and it will pick up making backups on this disk right where it left off.

You can periodically swap the drives again to update your offsite backup and Time Machine will automatically do an incremental backup that will bring the backup volume up to date with your system. These won’t take so long as the first full backup did and this is just what you want.

And of course there’s no need to stop at just two backups.  You can have as many backup volumes as you want. In fact, with hard drives so cheap these days, it’s probably worth having at least two on hand and maybe three if you really want to protect your data. With today’s digital lifestyle resulting in so much of our important information being stored on our Macs, such as the family photos, our music libraries, our home movies, not to mention all our work documents and school projects, it can be devastating to lose all this data in the event of a hard drive failure. Having multiple backups can help reduce the risk of this occurrence, particular if at least one backup is stored offsite to help prevent lose in case of fire or theft of the main system.