Set up Time Machine on an external SSD and restore a file

Plug the external SSD straight into the USB-C or Thunderbolt port of the Mac. Use the cable supplied with the drive and avoid a hub while the first backup runs.

When you connect an empty drive for the first time, macOS may ask whether you want to use it to back up the Mac. You can close that question and set everything up in System Settings instead.

Open System Settings from the Apple menu at the top left. Click «General» in the sidebar and then «Time Machine» on the right.

You now see the list of backup disks. On a new Mac the list is empty.

Click «Add Backup Disk». If a backup disk is already set up, click the button with the plus sign instead.

A list of the available drives opens.

Select the connected SSD in the list and click «Set Up Disk». In the window that follows, switch on «Encrypt Backup». Enter a backup password, confirm it and store it in the company password manager straight away. The password hint must not contain the password. Then click «Done».

Depending on the state of the SSD, the Mac asks whether the drive may be erased so that Time Machine can use it. Click «Erase», or choose a different disk. Erasing permanently removes all files on the SSD.

If backups from another Mac are already on the SSD, macOS asks whether this Mac should claim them. Confirm this only if the existing backups are meant to belong to this Mac from now on.

Shortly after the setup, the first backup starts on its own. You can follow the progress in the «Time Machine» section of System Settings.

The Mac stays usable in the meantime. The first backup covers all of your data and takes several hours, depending on how much there is. After that, Time Machine only saves the changes.

Leave a notebook connected to mains power so that the first backup runs without interruption.

Open System Settings and click «Menu Bar» in the sidebar. You may need to scroll down. In the «Menu Bar Controls» section, switch on «Time Machine». The Time Machine icon appears at the top right of the menu bar.

Click the Time Machine icon in the menu bar. The menu shows when the last backup ran. With «Back Up Now» you start a backup immediately, for example before an update.

For the rhythm, choose «Open Time Machine Settings» in the same menu and click «Options…». Under «Back up frequency» you decide whether Time Machine backs up automatically on a schedule, for example hourly, daily or weekly, or only manually. Then click «Save».

Time Machine keeps hourly backups for 24 hours, daily backups for the past month and weekly backups for all earlier months. Once the disk is full, Time Machine deletes the oldest backups.

Leave the SSD connected. In the Finder, open the window of the folder the file used to be in, for example «Documents». If an item is missing from the desktop, you do not need a window.

Click the Time Machine icon in the menu bar and choose «Browse Time Machine Backups». A short message may appear while the Mac connects to the backup disk.

You can also open Spotlight with Command-Space and type «Time Machine».

Use the arrows next to the window or the timeline at the right edge of the screen to go back until the file you want appears in the window.

The red mark in the timeline shows the backup currently on screen. A pulsing grey mark means that this backup is still loading or being checked.

The search field of the window also works inside the backups.

Select the file and press the space bar to check the contents in «Quick Look». This way you make sure you have the right version.

Select one or more items, whole folders are possible too, and click «Restore». The item goes back to its original location.

If you need an earlier version of a document that is still open, use «File» in the menu bar instead, then «Revert To» and «Browse All Versions».

Eject the SSD in the Finder before you unplug the cable. Click the eject symbol next to the name of the disk in the sidebar.

The next time you connect it, Time Machine picks up the schedule again on its own.