Mac Basics: Time Machine backs up your Mac

Learn how to set up Time Machine to perform backups, how to restore items, how to use System Restore to return your entire Mac to a specific date, how to migrate backups to a new Mac, and more.

Time Machine is the built-in backup feature of OS X that works with your Mac and an external drive (sold separately) or AirPort Time Capsule. Connect the drive, tell Time Machine to use it, and relax. Time Machine automatically backs up your entire Mac, including system files, applications, accounts, preferences, email messages, music, photos, movies, and documents. But what makes Time Machine different from other backup applications is that it not only keeps a spare copy of every file, it remembers how your system looked on any given day—so you can revisit your Mac as it appeared in the past. Time Machine keeps hourly backups for the past 24 hours, daily backups for the past month, and weekly backups until your backup drive is full.

OS X Lion and later let you:

  • Encrypt your Time Machine backup.
  • Start from OS X Recovery using your Time Machine backup disk. With OS X v10.7.3 and later, Time Machine backs up the Recovery System on your Mac to your backup drive as well. This lets you use your Time Machine drive to start up your Mac if needed. Simply connect your Time Machine drive, then hold down the option key at startup to select it as your startup disk.

OS X Mountain Lion and later let you:

  • Encrypt AirPort Time Capsule backups and network backup.
  • Select multiple backup destinations that Time Machine will rotate through for backup cycles.
  • Complete backups when the Mac is in Power Nap (on compatible Macs).

OS X Mavericks lets you:

  • Stay informed of your initial backup status using Notifications. Time Machine displays a notification after the first backup is complete, or if any issues arise during the initial backup. 
    time machine notification

Time Machine menu

The Time Machine menu in the menu bar also lets you know when a backup is happening in the background. While a backup is in progress, the menu icon includes an additional arrow in Mavericks, or rotates counterclockwise in earlier versions of OS X.

 idle icon    time machine alert menu iconalert icon
idle backup
in progress
cannot back up

You can check the status of your backup by clicking on the Time Machine icon in the menu bar. If you see a Time Machine icon in the menu bar that indicates a possible issue, click the icon to learn what is preventing Time Machine from backing up.

time machine menu

Note: You can also select this menu while holding down the Option key to see additional options: verify your backup disk, or manually select a different backup disk to browse.

Learn More

For additional information about setting up and using Time Machine, select one of the topics below.

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Setting up Time Machine backups using an external drive

Setting up Time Machine is as easy as connecting an external drive to your Mac via Thunderbolt, FireWire or USB.

If you haven't specified a Time Machine backup device and you connect an external drive, Time Machine will display a dialog similar to this one:

Note: The "My Backup (489.5 GB)" text in the above example is replaced with the name and capacity of the external drive you connect.

  • Click "Use as Backup Disk" to confirm you want to use the drive for Time Machine backups.  Time Machine preferences opens with this drive selected as your backup destination.
  • Check "Encrypt Backup Disk" if you want to encrypt the Time Machine backup external drive using FileVault 2 (OS X Lion and later).

That's all you have to do for Time Machine to automatically back up your Mac. The Time Machine pane of System Preferences should look similar to this:

Note: The "My Backup" and drive capacity in the above example are replaced with the name and capacity of the external drive you configure as your Time Machine backup.

Manually preparing a new disk for Time Machine

  1. If you want to erase a disk before using it with Time Machine, follow these steps:
  2. Open Disk Utility (located in the Utilities folder).
  3. Connect the disk if it isn't already attached.
  4. In the left side of the Disk Utility window, select the disk you want to use with Time Machine.
  5. Optional: If you want to partition the disk, click the Partition tab and select a layout. Make sure "Mac OS Extended (Journaled)" is selected in the Format menu for the partition that will be used for backups. Click Apply.
  6. Click the Erase tab.
  7. Optional: If you want to securely erase the disk, click Security Options to configure, then click OK.
  8. Click Erase.
  9. After erasing, open Time Machine preferences in System Preferences and configure as described in the section above.

About the first backup

You may want to set up Time Machine in the evening so that the initial backup can be done overnight. It may take a while, depending on the size of your OS X volume. You should not interrupt the initial backup. You can continue to use your Mac while Time Machine backs up.

Once the initial backup is completed, Time Machine performs subsequent hourly backups of only the files that have changed on your Mac since the last backup (as long as your backup drive is connected).

Tip: You can manually initiate a Time Machine backup cycle at any time by choosing Back up Now from the Time Machine menu, even if you have Time Machine preferences set to off.

Manually selecting a backup drive

You can manually select a backup drive in the Time Machine pane of System Preferences.

  1. Choose Time Machine menu > Open Time Machine Preferences…
  2. If the padlock in the lower left is locked, click it and enter an administrator name and password to unlock.
  3. Click Select Disk….
  4. Select a drive, then click Use Disk.

Note: In OS X Mountain Lion and later, if a backup device is already selected, you will be prompted to click one of these options:

  • Cancel - This will cancel the process and leave your Time Machine settings as is.
  • Replace (current drive name) - Time Machine will stop using the current drive and replace it with the new selection.
  • Use Both - Time Machine cycles backups through multiple backup devices. See the "Setting up an additional Time Machine backup (OS X Mountain Lion or later)" below for details.

Choosing a backup drive

When you select a drive in Time Machine preferences to store your backup information, every available drive that can be used to store backups is listed. If you’ve partitioned a drive, qualified partitions are also listed. If you don't see your drive listed, check the following:

  • Time Machine can only back up to a external drive connected to an AirPort Extreme 802.11ac base station. Time Machine cannot back up data to external drives connected to other AirPort Extreme base station models.
  • The most common format for a Time Machine backup drive is Mac OS Extended (Journaled) format, but Time Machine also supports Mac OS Extended (Case sensitive, Journaled) and XSan formats.
  • Time Machine cannot back up to a drive formatted for Microsoft Windows (NTFS or FAT format).  If you select an NTFS or FAT-formatted drive, Time Machine prompts you to reformat the drive. Choose a different drive or reformat the drive in Mac OS Extended (Journaled) format. Important: Because reformatting erases any files on the drive, only do this if you no longer need the files, or if you have copies of them on a different drive.
  • If the drive is partitioned using the Master Boot Record (MBR) partition type, some partitions may not be available for use with Time Machine. The GUID Partition Table (GPT) type is recommended.
  • Time Machine works best if you use your backup drive only for Time Machine backups. If you keep files on your backup drive, Time Machine won’t back up those files and the space available for Time Machine backups will be reduced. 

Setting up Time Machine for backups using AirPort Time Capsule

If you have an AirPort Time Capsule on your home network, you can use it as your Time Machine backup device. See the documentation that came with your AirPort Time Capsule for information about setting it up on your home network. Once your AirPort Time Capsule has been configured for your home network:

  1. Open Time Machine preferences and click "Select Disk…". 
  2. From the sheet that appears, select the AirPort Time Capsule you would like to use for backup.

In OS X Mountain Lion or later you can select the "Encrypt backups" option to encrypt the backup on the AirPort Time Capsule using FileVault 2.

Tip: Click "Set up Other Time Capsule" to open AirPort utility to setup and configure your AirPort Time Capsule. Enter the name and password or password only that you set for your AirPort Time Capsule via the Airport Utility. 

About the first backup to an AirPort Time Capsule

Your initial backup may be faster if you leave your computer in the same room as the AirPort Time Capsule, or use an Ethernet cable to connect your Mac to one of the Ethernet ports on the AirPort Time Capsule. You should not interrupt the initial backup connection by sleeping or shutting down the computer. You can continue to use your Mac while Time Machine backs up.  Additional information is available about backing up with an AirPort Time Capsule for the first time

Once the initial backup is completed, Time Machine performs subsequent backups of only the files that have changed on your Mac since the last backup was performed. Subsequent backups happen when a connection between the Mac and the backup drive is available. You can manually initiate a Time Machine backup cycle by selecting "Back up Now" from the Time Machine menu in the menu bar.

Setting up an additional Time Machine backup (OS X Mountain Lion and Mavericks)

Time Machine in OS X Mountain Lion allows you to add additional Time Machine backup destinations to your existing Time Machine backup list. You can use this to create an extra Time Machine backup, or a Time Machine backup at another location. For example, you can have a Time Machine backup destination at home, and a backup destination at work.

Simply add an external drive or AirPort Time Capsule using the Time Machine pane of System Preferences with the steps detailed above.

Once configured, Time Machine rotates backup cycles across the configured Time Machine backup destinations. If a destination cannot be found at the time of the backup cycle, Time Machine skips that destination. Time Machine tries the next backup destination on the list until it can find a backup destination to interact with and complete a backup.

Selecting items to exclude from the backup

In Time Machine preferences, click the Options button to adjust settings. A sheet similar to this appears:

This sheet allows you to exclude files, folders, or entire volumes from being backed up. You might want to do this to avoid filling up your backup drive. For example, if you regularly modify a very large file (greater than 1 GB, for example), you might want to add that specific file to the "Exclude these items from backups" list. Time Machine backs up modified files, regardless of how much, or how little, the file  changes between backups. 

The "Notify after old backups are deleted" option tells Time Machine to warn you when older backups are removed from your backup drive to make space for more recent backups.  

Restoring data from Time Machine backups

With Time Machine, you can go "back in time" to restore files, versions of files, or your entire system. Make sure your backup drive is connected and mounted. If it is not, Time Machine alerts you that "Your Time Machine backup disk can't be found."

Restoring specific files or folders

Choose Enter Time Machine from the Time Machine menu. The restore interface appears. You can literally see your windows as they appeared "back in time." 

You can use the timeline on the right side of the window to reach a certain point back in time. The timeline shows the times of all backups on your backup drive. If you don’t know exactly when you deleted or changed a file, you can use the back arrow to let Time Machine automatically travel through time to show you when that folder last changed.

Note: Dates in pink indicate the data resides on your Time Machine backup device. Dates in white indicate the data resides on your Mac. In OS X Lion v10.7 and later, portable Macs include local snapshots

You can also perform a Spotlight search from the Finder. Simply enter a search term in the Spotlight search field, and use the back arrow to have Time Machine search through your backups to find what you are looking for.

Before you restore a file, you can also use Quick Look to preview a file to make sure its the one you want. Highlight the file and press the Space Bar to bring up a quick look.

To restore, select the file/folder and click the "Restore" button. The file will automatically be copied to the desktop or appropriate folder.  If the file you are restoring has another file in the same location with the same name, you will be prompted to choose which file to keep or keep both.

Restoring your entire system from a backup

If you are restoring a backup made by a Mac to the same Mac

Hold down the Command and R keys at startup to start the computer from the Recovery system. The Recovery menu that appears includes the option to restore from a Time Machine backup. If you are using Mac OS X Snow Leopard, start your computer from the installation disc. Then use the "Restore From Time Machine Backup" utility.

Note: If "You can't restore this backup because it was created by a different model of Mac" appears when restoring a backup that was made on a different Mac, follow the onscreen instructions. If you are trying to restore your backup from one Mac to another Mac, use Migration Assistant to transfer data from the backup instead, as described in the next section.

Migrating a Time Machine backup to a new Mac

When you get a new Mac, you can transfer all of your applications, files, settings, and other information from a Time Machine backup you've already made. When you start up your new Mac for the first time, the Setup Assistant asks you if you would like to restore from backup. If you've already set up your new Mac, you can use the Migration Assistant (located in Applications/Utilities) to do the same thing.

After Migration Assistant completes the transfer and you select your existing Time Machine backup drive, you will be prompted with "Inherit Backup History". Once selected you will be able to continue to use your existing Time Machine backup on your new Mac.

Additional Information

If your backup drive fills up

As your backup drive begins to fill up to its capacity, Time Machine intelligently deletes the oldest backups to make room for newer ones. It also alerts you if the "Notify after old backups are deleted" option is selected in Time Machine preferences.

Consider the following options if your backup disk is filling up often, causing your oldest available backups to be erased sooner than you might want:

  • Use additional drives for your backups, or transfer your backups to a new, larger drive using the steps in Time Machine: How to transfer backups from the current backup drive to a new backup drive.  
    •  Tip: You can also browse the original backup drive for past backups by using "Browse other Time Machine Disks"--to see this choice, hold the Option key then click the Time Machine menu in the Finder (to see the menu, "Show Time Machine status in the menu bar" must be selected in Time Machine preferences.
  • Reduce the amount of information being backed up by adding to the "Exclude these items from backups" list in Time Machine preferences, as mentioned above. Your backup drive will fill up less often.
  • Delete file(s) that are no longer needed (such as from your desktop, Documents folder, or other Home folder locations), so they will no longer be backed up.  You can also enter the Time Machine restore interface and find files that can be removed from the backup drive itself to conserve space. To do this, select the file(s) and from the Action pop-up menu (gear icon) in the Time Machine Finder window choose "Delete All Backups of...". Be sure to only delete files you are sure you won't need or want to restore later.
Important: Information about products not manufactured by Apple is provided for information purposes only and does not constitute Apple’s recommendation or endorsement. Please contact the vendor for additional information.
Last Modified: Aug 27, 2014
  • Last Modified: Aug 27, 2014
  • Article: HT1427
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