When Your Mac Startup Disk Is Almost Full, Here’s What You Should Do

Getting the message that says “Your startup disk is almost full” on your Mac device may pose a problem down the road. Disregarding the alert won’t help much - it will show up persistently until the issue is properly addressed. The chances are high that your first reaction will be an astonishment: "How come my Mac got filled up so fast?" you wonder. Deleting some files to make more space on the startup disk is the foremost thing you may consider. However, haphazardly removing the files is not the best approach to get the issue sorted out. First, you need to learn a few things about Mac’s startup disk to understand how to fix the problem.

message "statup disk almost full"

What Is A Startup Disk on Mac?

A Mac computer uses a hard disk drive (HDD or SSD) to store the information. A startup disk is a partition of a hard drive containing an operating system – data that you cannot erase. Why? Because otherwise the device just won't launch. A startup disk may not use the full capacity of an HDD/SSD, leaving some empty space on it. It means that more than one partition could be created within a single hard drive. As a rule, most Mac users find it unnecessary to separate partitions and use one disk where both an operating system (OS) and user data (applications) are stored. More advanced Mac users may select to use two or more separate partitions on a hard disk. This is a good thing to do to keep your data organized as the overall storage space is divided between the startup disk containing an OS and other volumes meant for user data.

Mac Storage Full? Don't Space Out

So, why is having enough free space on your startup disk important? Does it impact Mac’s performance? Exceeding the 85% of hard-disk drive capacity will eventually trigger warning message and, possibly, slow work down. To stop getting the error on your MacBook Air or other Mac device, you need to create a sufficient amount of free disk space. Some users may try to restart their computer, empty the trash bin, or delete the old files to escape the “Your Mac Startup Disk Is Almost Full” alert. Still, this is only a temporary solution. To fix the problem once and for all, you need a more in-depth approach to freeing the space on your Mac.

How to Clear Startup Disk Space On Mac?

There are three major ways to free up hard drive space on Mac:

  • Manual cleanup
  • Using built-in Mac utilities
  • Using third-party apps

Before starting to clean up Mac hard drive, it’s wise to backup your Mac in order to protect the important data. Using built-in backup utilities ensures that you will be able to recover individual files or an entire system from your backups if something goes wrong.

How To Delete Files From Startup Disk Manually?

If you wish to clean up your Mac startup disk DIY-style, you'll need to see what is taking up space. Check the Downloads folder, Applications folder, and the "All My Files" view for outdated apps, temporary files, and other files that eat the startup disk space. To make space on your Mac manually, do the following:
  • 1. Launch a Finder window and go to List view.
  • 2. Choose View -> As List. You may click the “List View” button at the top of the Finder window.
  • 3. Choose the needed file arrangement - “Size,” “Kind,” “Tags,” “Date Last Opened,” etc.
  • 4. Delete the files that occupy too much space.
Folder "all my files"

Being a UNIX-based system, MacOS has scheduled maintenance routines for cleaning up the disk space. They are aimed to increase the amount of free space by deleting the system logs and temporary files. As a rule, maintenance scripts run automatically at a particular time if your Mac device is not shut down or in a sleeping mode. However, failing to run these scripts results in log files piling up and consuming free space on your Mac. To get more room on your startup disk, you may need to run these maintenance scripts manually on a regular basis.

It’s possible to run daily, weekly and monthly maintenance scripts at once:

  • 1. To access Terminal, go to Applications -> Utilities
  • 2. Using Admin account, type in the following command: a. sudo periodic daily weekly monthly
  • 3. Press Return
  • 4. Type in your Admin password when prompted, then press Return.

Once all three scripts are executed, the Terminal prompt will return. It is possible to run each of the above scripts separately. For instance, to run a daily script, use the following command: sudo periodic daily.

Conducting a manual cleanup has its pros and cons. On the one hand, you have full control of the process, which means that no files are deleted without your knowledge and consent. On the other hand, running a manual cleanup is time-consuming compared to using automatic cleanup tools. Manual cleanup won’t help you get rid of hidden files that can be uncovered during an in-depth machine check.

run terminal

Dealing with Mac Startup Items

Startup items (login items) are launched automatically every time you start your Mac device. Apparently, they affect the load on Mac's startup drive. As a result, these services and applications can increase Mac’s booting time and slow down the system performance. Yet, the chances are huge that you don't really need all of them launching right away. Hence, expelling some of those apps from the startup list can be fully justified to speed up booting process.

How to Remove Mac Startup Programs?

To clean up Mac startup programs in your account, do the following:
  • 1. Access the System Preferences -> Users & Groups.
  • 2. Click your username.
  • 3. Click on the Login Items tab.
  • 4. Mark out and remove the startup items using the "-" symbol.

To remove Mac startup items for all accounts manually, follow these steps:

  • 1. Open a new Finder window.
  • 2. Press Command + Shift + G.
  • 3. Type in the following directory path: /Library/StartupItems.
  • 4. Move any of the files in this folder to another location (directory).
  • 5. Restart your Mac to apply changes.

In case something goes wrong, you can always restore the files from your alternate location.

How to Clean Up Mac Hard Drive Using Built-in Mac Utilities?

mac hd available space

Mac OS Sierra provides users with Optimized Storage feature, a set of built-in utilities for disk storage optimization:

Store in iCloud

Storing files in iCloud will help you save the disk space by storing rarely used files, images, email attachments, etc. in the cloud, making them available on demand. To access the Store in iCloud settings, do the following:

  1. Choose Apple menu, then go to System Preferences.
  2. Click iCloud, then click the ‘Options’ button next to iCloud Drive.
  3. To turn off iCloud Drive, deselect the iCloud Drive.
Optimize Storage

It is possible to optimize the disk storage by removing watched movies and TV shows. To configure this option in iTunes, do the following:

  1. Choose iTunes -> go to Preferences -> click Advanced.
  2. Select “Automatically delete watched movies and TV shows.”

Also, it’s possible to configure the email attachments download in Mail.

  1. Choose Mail -> go to Preferences -> click Accounts.
  2. Enter the Account Information section of your email account.
  3. Change the settings for Attachments pop-up menu (Recent or None).
Empty Trash Automatically

Empty Trash Automatically feature allows deleting the files that have been in the Trash for over 30 days no questions asked.

Reduce Clutter

Reduce Clutter functionality is meant to detect large files or files you might no longer need to remove them from your disk.

Compared to manual clean up, using Mac built-in utilities has its benefits. Integrated into the OS, these services are intuitive and easy to use. There’s no need to work out how to run the Terminal or look for specific files selectively to clean up Mac hard drive. These system utilities have options, which allow making specific settings while leaving the rest intact. However, if you’re looking for an in-depth approach and performance boost, you won’t get much. For this, you should consider using third-party applications.

Going Above and Beyond: How to Clear Disk Space On Mac with Third-Party Apps?

Third-party apps help to improve your Mac performance, clean up junk, free up memory, and create the hard drive space (including the startup disk). Apart from the extensive cleaning functionality, they offer various features for boosting the operating system speed when its speed goes low. Third-party applications are capable of performing in-depth checks for the issues overlooked during the manual cleaning. Also, they provide the following benefits:
  • reduced Mac boot time;
  • improved system performance;
  • efficient applications uninstall;
  • caches, logs, duplicate files, language files cleaning;
  • anti-malware functionality;
  • disk defragmentation.

The advantage of third-party apps is an ‘all-in-one-place’ approach. It allows troubleshooting a vast array of issues within a limited time. All in all, third-party applications are comprehensive solutions for cleaning and servicing your Mac device.

Final Thoughts

“Your Mac Startup Disk Is Almost Full” message is a typical problem many Mac users face. There are three ways to deal with this issue and clean up Mac hard drive more or less efficiently. Users can resort to manual cleanup, built-in Mac utilities, and third-party applications. Every method has its pros and cons, but using third-party apps appears to be the most efficient in terms of "efforts-result" ratio. A vast range of functionality provided by such software allows making the process of clearing disk space on Mac fast and efficient.