Startup Disk Full on Your Mac? Here's How to Fix It

Mac boot disk space is insufficient? Don't worry, this guide will teach you how to check and free up Mac boot disk space.

When your Mac displays a "Disk Space" warning, it usually means that the boot disk space is full. A boot disk is a hard disk or solid state drive that stores the Mac operating system (macOS). Most of the time, it is a built-in drive for your Mac and where all your local files are stored. This means that your documents, movies, music, downloads, and other files are stored on the startup disk, along with macOS and other applications. Over time, installing more applications, uploading more photos and creating more documents, the boot disk is easily filled. Unfortunately, most modern Macs do not allow upgrades to boot disks to increase storage space. So if your Mac boot disk is full, the only solution is to clear various files to free up space.

How to check the free space of the boot disk?

Even if your Mac doesn't issue a warning, you should check the remaining free space regularly. This way, you can solve insufficient disk space and other storage problems in a timely manner.

Here is the easiest way to check the available space on your Mac:

1. Click the Apple logo in the upper left corner of the screen.
2. Select About this machine.
3. Click "Storage" and wait for the chart to load.

At the top of the screen, you'll see the name of your Mac's boot disk (usually "Macintosh HD"), as well as a breakdown of total storage and current usage. Hover the cursor over the chart to see how much space is used for each category; hover the cursor over the white area to the right to see what storage space is remaining. Ideally, about 20GB of available storage should be reserved.

How to free up Mac boot disk space?

Now you should have a clear understanding of how much space is left on the boot disk and what types of files take up storage space. It's time to clean up some space.

Here are some of the best ways to free up boot disk space:

1. Empty the Trash and Download Folders

Trash and download folders on your Mac will accumulate many useless files over time. Download folder saves all the content you downloaded. Unless you clear, the Trash will keep everything you deleted. These two folders may take up several GB of space on the boot disk. The solution is of course to delete unwanted download files.

The steps are as follows:

1. Open Finder and select the Download folder from the sidebar.
2. View the downloaded file and drag the unwanted files to the Trash.
3. Now open the Trash from the Dock and click "Empty".

You will find that this frees up more free space on the boot disk. If so, you may need to learn how to automatically clear the trash every 30 days on your Mac.

2. Delete Time Machine snapshots

If the About Native window shows that a large amount of space on your Mac is taken up by System, Other, or Backup files, you may be able to delete them by simply backing up your Mac. This happens if you usually use Time Machine to back up your Mac but haven't backed up for a while. In this case, your Mac will save many Time Machine snapshots to the boot disk and transfer them to an external drive the next time you complete the backup.

Simply connect your external Time Machine drive and go to System Preferences > Time Machine > Backup Now.

3. Delete old iOS and iPadOS backups

You may find a lot of storage space taken up by local iOS or iPadOS backups. If you no longer need these backups (for example, you are now backing up to iCloud), you can delete them using the About Native window.

The steps are as follows:

1. Click the Apple icon and select "About this machine" from the upper left corner of the menu bar.
2. Go to the Storage tab and click Manage.
3. Select "iOS Files" from the sidebar to view all iOS and iPadOS backups.
4. Select any backup you don't want to keep and click Delete to delete it.

4. Uninstall apps that are no longer used

Open Finder and select Apps from the sidebar to view all the apps installed on your Mac. Check out the list to see if there are any apps you no longer use, you can uninstall them to free up more space and clean up the boot disk.

The fastest way to uninstall a Mac application is to drag it to the trash, but this usually leaves many hidden files in the system and library folders that still take up space. Alternatively, you can use the Mac App Cleanup Tool to uninstall the application and delete all relevant files at once.

5. Upload or export the largest file

Most of the storage space on your Mac boot disk may be occupied by your own personal files. This includes music, movies, photos and documents. Of course, you can't delete most of these files, but you can free up space by moving them from your Mac to somewhere else.

There are two ways to do this:

1. Export these files to an external storage drive.
2. Upload these files to cloud storage services such as iCloud.

To export a file, connect an external drive and use a finder to drag the relevant file onto the drive. After the Finder has copied the files to an external drive, you can safely delete them from your Mac. The way to upload files depends on the cloud storage service you choose, but iCloud is the most commonly used service. You can also read the best unlimited cloud storage reviews or stick with built-in iCloud storage.

To upload a file to iCloud Drive:

1. Go to System Preferences > Apple ID and select iCloud from the sidebar.
2. Open the iCloud Drive Options window and enable Desktop and Document Folders.

This will automatically upload all files in your desktop and document folders to iCloud Drive, freeing up a lot of space on your Mac boot disk. You may also need to enable Photos in your iCloud settings to upload your photos.

6. Find and delete duplicate files

You may have a lot of duplicate files taking up extra space on your Mac. This is sometimes caused by software errors in copying files in the background, but it can also be caused by user errors.

Fortunately, duplicate files can be easily found and deleted using MacKeeper's duplicate file finder. With just two clicks, this feature can scan your entire Mac for duplicate files and delete any files you don't need to keep.

7. Clean unnecessary system files

If your Mac boot disk is still full after completing all of the above steps, then there may be a lot of hidden system files that take up your storage space. These files include redundant caches from basic parts of the operating system to useless websites.

Of course, you want to keep all the basic files while finding and deleting everything else is a big task.

We'll show you some ways to find and delete unnecessary system files, including log files, but you should know that doing this manually is time consuming. If you make a mistake, it may even cause problems with macOS.

For simplicity, using MacKeeper's "Safe Cleanup" feature is usually faster and easier, and it automatically finds and deletes any system files you can safely delete.

But if you are determined to delete these system files yourself, here are some things to look for:

1. Open Finder and select Go to > Go to Folder from the menu bar.
2. Visit the following file path to find any cache that can be deleted (do not delete any cache that contains "Apple" in its name):

• /Library/Caches/
• ~/Library/Caches/
• /System/Library/Caches/

3. Now access these file paths to delete unwanted log files:

• /Library/Logs/
• ~/Library/Logs/

Automatically keep boot disk clean using MacKeeper

If you use Mac disk cleaning tools such as MacKeeper to automatically clean your Mac regularly, you can forget about the issue of boot disk full. While you can clean up the boot disk yourself, it's much faster to have MacKeeper do the job for you. Especially if you set up "auto scan" to run these checks in the background.

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