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What Is System Data On a Mac and How to Clear It

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What Is System Data On a Mac and How to Clear It

Key Points

  • System data refers to files other than apps, documents, photos, music, and mail and includes temporary files, caches, system logs, and other technical bits of data.
  • To clear system data on a Mac, you can use tools like Disk Utility to check for errors and repair them, optimize storage to enable space-saving features, clear library files by deleting unused application files, and remove backups from Time Machine.
  • If other methods fail, you can use a third-party cleaning app like CleanMyMac X to clean up your storage.

Luckily, computers these days come with a lot more storage than they used to. However, every file and every download add up, especially if you’ve been using the same computer for several years. While it can be relatively simple to find and delete unused apps and documents, much of your storage on your Mac will be labeled as “System Data.” This somewhat confusing term isn’t very clear. You might be scratching your head trying to figure out exactly what this means (and why so much of your storage space is taken up by it). We’re going to demystify what macOS means by this term and what you can do to free up your space.

What Is System Data?

The exact name given by your Mac may not be system data, depending on the version of macOS you’re running. Older versions may list it as “Other”, or simply as “System.” It may even be lumped under the “macOS” umbrella. In any case, system data refers to files other than apps, documents, photos, music, and mail. In reality, some of these files will fall under one of these categories (downloads are often included), but if the file is hard to classify, there’s a good chance it’ll be part of your system data. The vast majority of the files are crucial to enabling your Mac to run smoothly. Think temporary files, caches, system logs, and other technical bits of data.

System data on Mac.
You can see the size of your system data under the “Storage” tab.

How Do I Access System Data On a Mac?

You can’t easily see a complete picture of what system data encompasses, but you can get an overview. Either go to the Apple Menu and then System Settings or click the Apple logo in the top left, then click “About This Mac.” If you go to the “Storage” tab, you’ll see a breakdown of how much free space you have. Often, your Mac will do a fairly good job of optimizing this data, but if you have a lot of unused apps and temporary files, system data can grow significantly. While somewhere around 15 to 50GB is pretty typical, sizes of up to (and over) 100GB aren’t unheard of.

Your system’s performance can be heavily impacted if storage space is scarce. For this reason, you may want to clear some of your data. However, we don’t advise tinkering too much, as this can damage your system. It’s a good idea to focus on other types of data first and see if you can either remove these or shift them to a cloud storage service or external hard drive.

How to Clear System Data On a Mac

Below are a few tools you can use to remove some of your system data.

Disk Utility

Disk Utility is a tool that can check your disk volume for errors, attempt to repair them, and manage your external hard drives. Simply open a Spotlight window by pressing cmd + spacebar, and then search for “Disk Utility.” Once open, you can view your hard drives and use the “First Aid” functionality along the top. This will check your disk for errors and repair them if necessary. Be aware that, although this process can only take a few seconds, it can take minutes or even hours. And your PC will be unusable during this time, so it’s best to do this when you don’t need your Mac urgently.

Disk Utility on Mac.
You can check your disk for errors and repair them using Disk Utility.

Optimize Storage

This can be an easy way to get some storage back. If you go to the storage tab from the Apple Menu, you can click the (i) next to a storage category or click the “Manage…” button. This will give you some tips for making space. You can click the “Optimize Storage” button to enable space-saving features, such as deleting shows you’ve already watched and older email attachments you don’t need. You can also turn on iCloud storage here, set your Bin to empty periodically and review individual files for deletion.

Mac storage recommendations.
From the “Storage” tab, you can use these recommendations to free up some space.

Clear Library Files

Most files in your library are essential, but some could be unused application files. If you want to remove these, follow these steps:

  • Open a Finder Window
  • Click “Go” in the taskbar, then “Go to Folder…”
  • Search for “~/Library”
  • Find the files you want to delete, move them to the Bin, and then empty the Bin.
Library on Mac.
By going to the user Library, you can delete lots of application files.

Remove Backups

Something that can greatly contribute to your system data is Time Machine. This tool is handy for keeping your system backed up, but these backups are stored internally. Your Mac should clear them when low on storage, but this doesn’t always happen. Of course, if you like to use Time Machine, then storing them externally instead of deleting them altogether is a great idea. But if you’re desperate to clear some space, you can use these steps:

  • Open a Spotlight window with cmd + spacebar and search for “Terminal”
  • Type “tmutil listbackups” and hit the Return key
  • This will display a list of your Time Machine backups. To delete the ones you want, enter “sudo tmutil delete” and then the path for the particular backup, i.e., “[username]/[disk name]/[YYYY-MM-DD]”. Hit Return to delete the backup.

You can also use this method to delete Time Machine snapshots. Instead:

Type “tmutil listlocalsnapshots /”
Once you see the list of snapshots, type “tmutil deletelocalsnapshots [snapshotname]”. Typically, the name will be a date with some text.

Terminal on Mac for clearing data.
With Terminal, you can delete Time Machine backups and snapshots.

Use a Third-Party Cleaning App

If all else fails, you can resort to a third-party app to clean up your storage. However, most of these cost money, and you don’t want to mess around too much with your system. The methods we’ve described should be able to make a big difference, but if you want to use an app, we’d recommend CleanMyMac X. This app has lots of functions, but the most useful one is for clearing out temporary and broken files. As with any method, proceed with caution, and always double-check what you’re deleting.

Frequently Asked Questions

What is system data?

System data contains all the crucial files your Mac needs to run properly, as well as files that can’t be categorised into apps, music, photos, videos, etc.

How do I access system data?

By going to system settings in the Apple Menu, or the Storage tab in “About This Mac”. Here, you’ll see the size of your system data.

Why is my system data so big?

This can be because you’ve had your Mac for many years, and you have a lot of temporary files, caches, and unused applications. It’s not uncommon to have around 50GB of system data, however.

How do I clear system data?

It’s not advised to play around too much with system data, as most of it is important. But you can use Disk Utility and your Mac’s storage recommendations, or go to your user library or the Terminal to delete application files and old Time Machine backups.

Can I use a third-party app to clear system data?

Yes, we recommend CleanMyMac X, as it has a tool for clearing system “junk.” However, you do need to subscribe to use this app, and you can free up space without it.

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