Backing up Your Data Using Time Machine

Protect your data with Time Machine's automatic backups

Time Machine can automatically back up all of your files, meaning you never have to worry about losing or accidentally deleting critical files. With Time Machine activated, you can restore files and data from automatically generated backups.

Unfortunately for many people, the first time they think about a backup is after their hard drive has failed, when it’s much too late to do anything about. Before you do anything else with your Mac, you should set up Time Machine.

Locate and Launch Time Machine

Man using Macbook Air
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Time Machine needs a drive or drive partition to use as the container for all the data that it copies or creates. You can use an internal or external hard drive as your Time Machine backup disc. If you’re going to use an external drive, it should be connected to your Mac and mounted on the desktop before you launch Time Machine.

Select the Backup Disc

Selecting backup disk in Time Machine
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Although you can select a drive partition to store your backups, you should avoid choosing a partition that resides on the same physical disc as the data you will back up. In the event the drive fails, there’s a high probability that you will lose access to both volumes, which means you will lose your backup as well as your original data. If your Mac has a single internal hard drive, we recommend using an external hard drive as your backup disc.

Heres' how to select the backup disc for Time Machine.

  1. Open System Preferences by selecting its icon in the Dock. Alternatively, select the Apple logo in the top menu bar, then select System Preferences...

  2. Select Time Machine.

  3. Choose Select Backup Disc... or Select Disk, depending on the version of macOS you are running.

  4. Time Machine will display a list of discs available for your backup. Highlight the disc you want to use, then select Use Disk. The first backup will begin within a few minutes. If you'd prefer not to begin the backup at this time, select Off.

    Time Machine Options
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Time Machine initially makes a backup of your whole computer, including the operating system, software applications, and your personal data files. It then makes incremental backups as changes are made to files.

Time Machine keeps:

  • Hourly backups for the last 24 hours
  • Daily backups for the past month
  • Weekly backups until your backup disc is full

Before you turn Time Machine loose, you may want to configure one or two options.

Configure Time Machine Options

You can instruct Time Machine to exclude certain files or items from its backups. By default, your Time Machine backup disc will be the only item on the list. You may want to add other items. Here's how.

  1. Open System Preferences and select Time Machine.

  2. Select Options... to bring up a list of items that Time Machine will exclude from its backups.

  3. Select the plus sign (+) to add a disc, folder, or file to the list of items that Time Machine should exclude from backups. Time Machine will display a standard Open/Save dialog sheet, allowing you to browse through the file system. Since this is a standard Finder window, you can use the sidebar for quick access to frequently used locations.

  4. Navigate to the item you want to exclude, select it, then select the Exclude. Repeat for each item you want to exclude. When you’re finished, select Done.

Warning: Avoid Backing up Windows OS

Some items you should add to this list include any files or folders containing a Windows operating system. Windows data files used by Parallels and other Virtual Machine technology look like one big file to Time Machine. Sometimes, these Windows VM files can be very large, as much as 30 to 50 GB; even small VM Windows files are at least a few GB in size.

Backing up large files can take a long time. Because Time Machine backs up the whole file every time you use Windows, it will also back up the whole file every time you make a change within Windows. Opening Windows, accessing files in Windows, or using an application in Windows can all generate Time Machine backups of the same large Windows data file. A better option is to eliminate these files from your Time Machine backup, and instead back them up using the backup tools available in the VM application.

Turn on Automatic Updates in Time Machine

Time Machine Status
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Select the checkbox next to Back Up Automatically to activate the automatic updates. (Older versions of macOS, there will be a simple On/Off toggle.

Once your backup disc is full, Time Machine will overwrite the oldest backups, to ensure that your current data is protected. If you ever need to recover a file, folder, or your whole system, Time Machine will be ready to assist.