Apple lets you use Time Machine to back up all data files, apps, and other things from your Mac that aren’t part of the macOS system installation. (Prior to macOS 11 Big Sur, you could also back up system files, but now you’re reinstalling the system.) This is flexible enough to let you mount multiple volumes that Time Machine alternately uses as backup targets. You can also have a set of volumes that you switch between your Mac and external storage, swapping them as often as you want to keep backups elsewhere up to date.

Every time you mount a Time Machine volume associated with your Mac, it gets added to the loop. The next time it’s its turn, the Time Machine algorithm will update it from the previous backup stored on that volume. If you keep multiple volumes mounted, you’ll have intermediate versions of files stored on one Time Machine drive and not another, even if you always keep at least one version for each cycle through a full set of drives.

What happens when you want to view files for recovery on all the volumes you use and used for backup, or limit the view to a specific volume? Or when you don’t have access to the computer from which the backups were taken?

In macOS 12 Monterey and earlier, clicking the Time Machine icon opens a menu item Enter the time machine. By default, backup snapshots from all currently mounted Time Machine volumes for your Mac are displayed. In macOS 13 Ventura, the label changes to the more informative View Time Machine Backups.

However, if you want to get files from a specific backup, you can Option-click the Time Machine menu and choose View other backups. (This setting hasn’t changed since the first versions of macOS came out with Time Machine.) You’ll see a dialog box showing the available volumes. Choose one and click Use Selected Drive. When you view files and view snapshots, you will only see the versions that are available on that drive.

Using this menu item, you can also select volumes created on or for other Macs, including disk images that you double-click to mount from a Time Machine network volume. You can browse and select files to recover through this volume by selecting it, but it’s essentially the same as navigating through the volume in the Finder.

For Time Machine online backups, mount the disk image and then figure out which snapshot you’re looking for. You can then dive into that snapshot to copy the files. For more information, see How to find a Time Machine backup for an offline volume.

This Mac 911 article is in response to a question posed by Macworld reader Lynn.

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