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, either a hard drive or solid state drive, 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 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 drive or flash drive, 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, as the name suggests, connects to your Mac directly via USB or Thunderbolt. External hard drives and flash drives are readily available from various retailers, and are usually reasonably priced.
When purchasing storage, I would recommend getting something that is at least twice the size 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; backups happen every hour when the disk is connected.
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.
To set up Time Machine for direct storage, connect the disk to your Mac and a dialog should appear asking if you want to use it for Time Machine backups. If you click the “Use disk” button, you’ll be prompted to create a password to encrypt your disk. In this dialog, you may want to select the “Remember this password in my keychain” checkbox, so you won’t need to enter the password when you connect the disk or restart your Mac, but anyone else would need to if they were connecting the disk to theirs.
Important: As this password is used to encrypt and decrypt your disk, it is critical that you remember it or keep it in a safe place. If you forget the password to an encrypted disk, the data on it will be lost forever.
If the dialog doesn’t appear, or if you’re setting up Time Machine for network attached storage, open System Preferences > Time Machine, click select backup disk, select your disk in the “Backup destinations” table, and click the “use disk” button. If you’re setting up Time Machine for network attached storage, encryption is optional.
Once the disk has been selected, Time Machine will make an initial backup. This may take a while, however you can continue to use your computer while this is happening. The speed of future backups depends on how much has changed since the last backup.
While in Time Machine preferences, you may also wish to select the “Show Time Machine in menu bar” checkbox, allowing you to enter Time Machine from anywhere.
Restoring a lost file
Note: if you prefer an audio demonstration, there is an AppleVis podcast that demonstrates this process.
It’s happened to all of us at some point, 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:
- 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.
- 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.
- Select “Time Machine controls” from the window chooser, accessed by pressing VO-F2 (or VO-Function-2 if you’re using a Mac with a Touch Bar).
- Either with the next and previous buttons or the timeline slider, navigate to the time you last had the file.
- Navigate back to the folder via the window chooser and brows it as you would any other folder to locate the file. When you find the file, you can press space to open Quick Look to preview it, making sure it’s the one you want.
- Select “Restore” from the contextual menu, accessed by pressing VO-Shift-M. Alternatively, you can click the restore button in the Time Machine 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.
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, to name just a few good sources. If you believe any of the information in this guide is inaccurate or if you want something clarified, sound off in the comments.