A Guide to Backing Up Your Mac with Time Machine

For macOS Sonoma

Intro

If you own a computer or mobile device, there’s one thing you’ve probably heard time and time again, back up your data. When your critical information is stored in only one medium, it is inherently vulnerable. The device’s internal storage medium could fail, complications could occur during an update or other system event, the device could get lost or stolen, or a flood or fire could break out at the device’s location. For this reason, it is advisable to always back up your data.

If you have an iOS or iPadOS device, you probably back up the data on it in iCloud. However, iCloud backup is not available on macOS. Thus in this guide, I will be discussing how to back up your Mac with Time Machine, the Mac’s built in backup utility.

Of course, like all backup solutions, it is not perfect, so it is generally advised to also have your data in another place, such as a cloud service. For example, you could back up your Mac’s entire disk with Time Machine and additionally store your documents and other files in iCloud Drive. This particular setup offers the dual advantage of having your content synced across multiple devices and having it stored in multiple locations.

What is Time Machine?

Time Machine is a backup utility built into macOS that allows you to create a backup of all your data on external storage that by default is updated every hour. If at any time you lose a file or something catastrophic happens to your Mac, you can “Go back in time” to retrieve the data. Likewise if you get a new Mac, the macOS Setup Assistant gives you the option to restore from a Time Machine backup, placing your data where you’d expect on the new Mac. If the Mac is already set up, Time Machine backups can be restored using Migration Assistant (located in the Utilities folder).

To use Time Machine, you’ll need external storage that is bigger than your Mac’s internal storage, as backups are made continuously over time. When the external disk is full, the oldest backup will be deleted.

Storage media, such as an external hard disk drive (HDD) or solid-state drive, (SSD) can either be directly connected to a Mac or over a network. In this guide, I will refer to this media broadly as the disk.

Note: Time Machine is not cloning software, meaning you cannot boot your Mac directly from a Time Machine backup. If you want to make a backup that you can start up from immediately, use something like SuperDuper.

Direct storage

Direct storage, as the name suggests, connects to your Mac directly via USB or Thunderbolt. Most external HDDs and SSDs work with Time Machine. While HDDs are generally cheaper than SSDs for the same amount of storage, SSDs are faster and more durable, as there are no moving parts.

When purchasing storage media, I would recommend getting an external disk that is at least twice the capacity of your Mac’s internal storage. For example, if your Mac has 512GB of internal storage, you should get a 1TB (1,024GB) external disk.

Network attached storage

If you don’t want to connect a disk directly to your Mac, you can use Time Machine to back up to one connected to your network. Common network attached storage (NAS) approaches include using a dedicated NAS device connected to your network, or connecting an external disk to the USB port on a wireless router.

An advantage to this method is that any time you’re on the network, your Mac will backup automatically, eliminating the need to carry around an accessory or have one of your Mac’s ports constantly in use. However, while convenient, network attached storage can be significantly slower than direct storage.

Setup

To set up Time Machine for direct storage, connect the disk to your Mac and a notification should appear asking if you want to use it for Time Machine backups. Press VO-N and select the notification from the Notifications menu, and choose “Set up” from the Actions menu (accessed by pressing VO-Command-Space). If you want to encrypt the backup, make sure the “Encrypt backup” toggle in the resulting dialog is turned on, enter a password for the disk in the provided fields, and click Done. As this password is the only way to access the disk's contents, it should be reasonably difficult for others to guess, but easy enough for you to remember.

The next time you connect the disk to your Mac, you'll be prompted for this password, and given the option to remember it in your Mac's Login keychain. This way, you won't need to enter the password when connecting the disk to your Mac, but others will if connecting the disk to theirs. Saved passwords in your Mac's Login keychain can be viewed and edited in Keychain Access (located in the Utilities folder).

If the notification doesn’t appear, or if you’re setting up Time Machine for network attached storage, open System Settings > General > Time Machine, click add disk, select your disk in the list, and click Set up disk. The resulting dialog will allow you to set encryption and other options for it.

Once the disk has been set up, Time Machine will make an initial backup. This may take a while, however you can continue to use your Mac while this is happening. The speed of future backups depends on how much has changed since the last backup.

By default, Time Machine makes hourly backups of your data. You can change the frequency of backups if you wish by clicking the “Options” button in Time Machine Settings and choosing an option from the “Backup frequency” popup menu.

Restoring a lost file

Note: For an audio demonstration of this process, check out the AppleVis podcast episode “Quick Tip: Restoring a Single File From a Time Machine Backup.”

It’s happened to all of us at one time or another, you’re looking for a file that’s just not there. You know it was there at some point, but may have been accidentally deleted. Use Time Machine to go back in time to retrieve the file. To do this:

1. In Finder, navigate to the folder where the file was located. If you don’t know, press Command-Option-Space to open the full search window and search for the file there.
2. Enter Time Machine either through the menu bar or with Spotlight or Siri. As Time Machine starts, Voiceover will play a swishing sound several times, after which you will be focused in the folder in the current time.
3. Select “Timeline controls” from the window chooser, (accessed by pressing VO-F2 (or VO-Globe-2 if you’re using a Mac with a Touch Bar).
4. Click the time you last had the file, and navigate back to the folder via the window chooser.
5. Brows the folder as you would any other to locate the file. When you find it, you can press space to open Quick Look to preview it, in order to ensure that it’s the one you want.
6. Select “Restore” from the context menu (accessed by pressing VO-Shift-M). Alternatively, you can click the restore button in the Timeline controls window.

If the folder where the file was located still exists in the present, the file will be restored and Voiceover will announce “Time Machine dismissed.” If the folder no-longer exists, you’ll be asked to choose a new location via the standard open and save dialog.

Conclusion

Due to its relative simplicity once you get the hang of it, Time Machine can be an integral part of your backup strategy. More information is available in your Mac’s built in help, Apple's Time Machine overview page, and the AppleVis forum, and if you have any questions or believe any of the information in this guide is inaccurate, sound off in the comments.