Is your Mac complaining about the lack of space on your Time Machine drive?
While you could solve the problem by investing in a bigger, better hard drive, you can often save some money by taking a critical look at exactly what youβre including in your Time Machine backups.
Most of the time, you can re-download a significant portion of your Macβs content from places like the App Store, or third party storage services like DropBox or Google Drive, so if youβre running low on space, then you should prioritize the content that canβt be recovered so easily.
In this article, Iβm going to show you how to exclude specific files, folders and apps from your Time Machine backups, so you wonβt need to splash out on a new drive. Plus, by reducing the size of your backups, youβll be able to create themΒ faster and retain them for longer, as Time Machine will be able to squeeze more backups onto your external drive.
What should I exclude?
While it varies from users to user, a good place to start is by excluding some, or all of the following:
- Content thatβs already backed up to an external service, such as iCloud, Google Drive or DropBox, or physical storage, such as a USB drive.
- Content that youβve purchased from an online store and can easily re-download at any point, such as iTunes content or Steam games, which are typically stored in ~/Library/Application Support/Steam/SteamApps.
- Media that youβve ripped from DVDs or CDs, assuming you still have access to the original discs.
You can easily re-download this content, or copy it back to your Mac in the event of data loss or hard drive failure, so ask yourself: whatβs the benefit to includingΒ all of thisΒ in my Time Machine backups?
You may also want to exclude the contents of your βDownloadsβ folder, as for most of us this folder is a dumping ground for files we vow to sort through later, only to wind up deleting the next time we need to recover some space on our hard drive.
If youβve created any virtual machines using a program such as VirtualBox, then you may want to exclude these from your backups, as emulated operating systems tend to be on the hefty side!
Finally, if your Mac includes particularly sensitive content, then this may also beΒ a candidate for exclusion. A Time Machine backup is essentially a copy of your content that exists outside of your Macβs hard drive, which can be a privacy and security concern for some users.
Check what Time Machine is excluding by default
Even though you can pick and choose specific items to exclude from your backups, Time Machine excludes a list files and folders by default, for example the contents of your βTrashβ folder and caches typically arenβt included in Time Machine backups.
Since you donβt want to waste time manually editing your Time Machine settings to exclude content thatβs already excluded by default, you should review exactly what macOS is already leaving out of your Time Machine backups.
Helpfully, macOS generates a text file that lists all the files, folders and apps that Time Machine is already ignoring:
- Open a new βFinderβ window.
- Select βGo > Go to Folderβ¦β from the βFinderβ toolbar.
- In the subsequent popup, enter the following path:
/System/Library/CoreServices/backupd.bundle/Contents/Resources/
- Click the βGoβ button.
- Control-click the βStdExclusions.plistβ file and select βOpen with > TextEdit.β
This file lists all the items that Time Machine is currently excluding, in the following format:
<array>
<string>/.MobileBackups</string>
<string>/MobileBackups.trash</string>
<string>/.MobileBackups.trash</string>
<string>/.Spotlight-V100</string>
<string>/.TemporaryItems</string>
While this might look complicated, βStringβ is essentially just a technical term for a piece of text, and an βarrayβ is a list of related strings.
This file also contains comments that provide context for each array, for example: βpaths where we need to capture top level folder to restore disk structure, but donβt want to backup any contents.β
Even if Time Machine is including an item in its backups, it may not be including every single piece of content thatβs related to this item. For example, iTunesβ cache and your Google Chrome whitelist and blacklist tend to be excluded by default, as all this information can be easily re-downloaded the next time you connect to the Internet.
You can review the list of files that individual programs are excluding from your Time Machine backups:
- Open a Finder window, and navigate to βApplications > Utilities > Terminal.β
- Copy/paste the following command into the Terminal window:
sudo mdfind βcom_apple_backup_excludeItem = βcom.apple.backupd'β
- Press the βEnterβ key on your keyboard.
- When prompted, enter your admin password.
The Terminal will now display a list of all your excluded files.
Exclude any folder from your backups
Once you know what apps, folders and files Time Machine is already excluding from your backups, you can start adding to this list:
- Navigate to βSystem Preferencesβ¦ > Time Machine.β
- Click the little padlock icon in the bottom-left, and enter your admin password when prompted.
- Give the βOptionsβ¦β button a click.
- To add an item to Time Machineβs βExcludeβ list, select the β+β button.
- Navigate to the file, folder or application that you want to exclude from your backups, and then click βExclude.β Note that if you select a folder, then the entire contents of that folder will be ignored, so if you wanted macOS to exclude all applications from your backups, then youβd simply need to select the βApplicationsβ folder and then click βExclude.β
- As you add items to this list, Time Machine will attempt to estimate the size of subsequent backups, so keep an eye on the βEstimated sizeβ¦.β value.
- Once youβre happy with all the items youβve selected, click βSave.β
Resume backing up items
If you change your mind and want to resume including an app, folder or folder in your Time Machine backups:
- Navigate to βSystem Preferencesβ¦ > Time Machine.β
- Give the βOptionsβ¦β button a click.
- Select the item you want to include in your Time Machine backups, and then click the little β-β button.
- Click βSave.β
Monitor the size of your backups
If youβre concerned that the size of your backups might spiral out of control again, then Time Machine can notify you whenever an old backup is deleted. Since old backups get deleted to make room for newer ones, this notification provides an indication about just how quickly your external drive is filling up. If the time inbetween these notifications is shrinking, then this usually means the size of your backups is on the rise.
To enable this feature:
- Navigate to βSystem Preferencesβ¦ > Time Machine > Options.β
- Select the βNotify after old backups are deletedβ checkbox.
- Click βSave.β
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