by Tom Nelson
You’ve been diligent about maintaining up-to-date backups of your Mac’s data by using Time Machine, but there’s a nagging worry in the back of your mind. How do you know the backups are any good?
That’s a good question, and one we should all ask about our backups. There are a number of ways to make sure your Time Machine backups are in good shape, and we’re going to cover most of them in this guide.
Before we move on to checking the state your backups are in, there’s an important demarcation in Time Machine technology to be aware of; a line in the sand, if you will. Time Machine backups created in OS X Yosemite and earlier have a more limited means of testing backups than those created in OS X El Capitan and later. We’ll include notes about which version of the Mac OS the verification method works in. With that out of the way, let’s get started.
Screen shot © Coyote Moon, Inc.
Verify Your Time Machine Disk
Before we attempt to verify files on a Time Machine backup, it’s a good idea to make sure the Time Machine disk doesn’t have any issues. Start by turning Time Machine off, and then use Disk Utility’s First Aid to verify that your Time Machine disk is in good shape. If any errors are noted, use Disk Utility’s Repair Disk option, as outlined at the link above.
The Eyeball Method of Checking Time Machine
This somewhat simplistic way of checking on the status of your backups is performed by using Time Machine to restore a file or two, and then checking (eyeballing) the files to see whether they seem to be intact. Before you complain that this way doesn’t seem very reliable, you’re absolutely right, but it does provide a quick and easy way to verify that the basics of Time Machine and your backups are indeed working.
The eyeball method will work for any version of Time Machine or the Mac OS. The only prerequisite is that you have a Time Machine backup in place on your Mac:
Enter Time Machine by either selecting Enter Time Machine from the Time Machine menu item, or launching the Time Machine app located in the /Applications folder.
Use the arrow in the Time Machine window to go back to an earlier time.
In the Time Machine Finder window, right-click a file and select Restore “file name” to… from the popup menu.
Time Machine will close.
After a moment you’ll be presented with a standard Finder Choose window to select a location to save the Time Machine file to. Browse to a location where you wish to save the file, and click New Folder. We highly recommend creating a new folder to restore to because a bug exists in some versions of Time Machine that causes all files that occupy the same folder as the selected file to also be restored. Restoring to a new folder will isolate the file if the bug occurs.
The file will be restored to the new folder location.
Open the restored file and examine it to make sure it’s in proper shape. This can be as simple as looking at the contents of a document, viewing a restored image, or checking file size and creation date.
If the file or files look good, and there were no disk errors noted when you ran Disk First Aid, then you can be pretty sure that your Time Machine backups are in good shape.
Note: If you did have errors when you used Disk First Aid, it may be time to look into replacement drives. Unlike other storage media we use, we recommend not tolerating drive errors on backups.