From this MiniTool article, you can know what the startup disk on your Mac is, what is taking up space on the Mac startup disk, the influence of startup disk full, and how to clear the startup disk space when the startup disk is full or your disk is almost full on your Mac.

What Is Startup Disk on Mac?

Like a Windows startup disk, the startup disk on your Mac is the disk that saved the operating system on your Mac. It is an important disk on your computer. If the operating system on the disk is corrupted or even the startup disk is damaged, your Mac computer will not boot normally.

What Is Taking Up Space on Your Mac Startup Disk?

As you know, a Mac computer’s disk is usually not as large as a Windows computer’s disk. As of 2020, Apple has improved the disk capacity and the maximum disk size can reach up to 8TB. But they are the Pro series, which are not widely used.

Most of the time, you should not worry about the disk space issue because macOS always do work online. This will not take up much disk space. However, what’s going on if you see a pop-up alert saying Your startup disk is almost full?

your startup disk is almost full

At this time, you should know what is taking up space on the startup disk of your Mac and then take some measures to clear the startup disk.

The hidden website cache takes much space on the startup disk. For example, statistics show that Google Chrome can create numerous cache folders after you visit some web sites. The size of the cache for one site can even reach up to 9 GB. This is quite surprising, but it is true.

As time goes on, the free space on the startup disk becomes less and less. One day, you may receive the startup disk full alert.

Besides, when a warning of Your disk is almost full pops up, it also means that there is not enough space on your Mac. It is equal to startup disk full. Likewise, you need to remove some files to free up disk space on your Mac computer.

your disk is almost full

What Does It Mean When Your Startup Disk Is Full?

When does it mean when you receive your startup disk is almost full alert?

It has two main influences:

1. You will soon run out of space on the startup disk.

Your startup disk is almost full is an early warning for you. It reminds you of cleaning up the startup disk. However, if you continue to use your Mac without cleaning up disk space, more and more data will be saved to the startup disk. One day, your Mac will run out of space and you will not use the machine as normal.

2. Your Mac computer will run slowly.

Some of you may think that your Mac computer will not be affected when there is space in the startup disk no matter it is much or less. It is wrong.

A Mac computer can convert the available free space on the startup disk into virtual memory that you use for day-to-day operations. In theory, there should be at least 10% of free disk space for your Mac to operate. If not, your Mac computer will run slowly and even face big trouble like Mac frozen.

When the machine detects that the available space on the startup disk is insufficient, it will give you a warning. This aims to remind you it’s time to clear the startup disk on your Mac.

What should you do when your startup disk is full on your Mac? In the following part, we will show you some solutions.

How to Clear the startup Disk?

If you want to clear your Mac startup disk, you need to delete the unnecessary files on it. Before doing this, you can check the storage space on your Mac.

How to Check the Storage Space on Your Mac?

  1. Click the Apple menu from the top-left corner of the screen.
  2. Click About This Mac from the drop-down list.
  3. Switch to the Storage section.

After these three steps, you can see the storage information of your Mac disk, including the files’ types, the free space on the drive, and more.

If your Mac Startup disk is full, you can do these things to free up disk space:

Tip 1: Remove the App Cache from Your Mac

The app cache files are necessary when you want to speed up processes. Once you complete the process, the cache files become useless. But these cache files will stay on the startup disk for a long time unless you manually delete them. When they are useless, they are junk files. To clean up your Mac startup disk, you need to remove them from the machine.

  1. Go to Finder > Go > Go to Folder.
  2. Type ~/Library/Caches.
  3. Go into each folder and then delete the files in it. You can also choose to only delete the files that take up the most space.
  4. You can repeat the above three steps for /Library/Caches to remove the App cache.

Tip 2: Empty Trash

When you delete files from your Mac, they will be moved to Trash. The files on Trash also occupy space on your Mac startup disk. As long as you are sure that you don’t need to use these files anymore, you can empty Trash to free up disk space.

To do this job, you just need to open Trash and then click the Empty button on the top-right side to remove files from your Mac. Since then, there will be more available disk space on your Mac.

Tip 3: Delete the Unnecessary Time Machine Backup Snapshots

Most people would like to use Time Machine to back up their Mac files to an external hard drive. You may think that the backup files are save to the external hard drive. But that’s not all. During the Mac data process, the local snapshots also automatically start once every 24 hours. That’s right. The snapshots are saved to your Mac, taking up disk space.

You can delete the unnecessary Time Machine backup snapshots to release space on the startup disk.

  1. Open Finder.
  2. Go to Go > Utilities.
  3. Double-click Terminal to open it.
  4. Type sudo tmutil disablelocal into Terminal, and press Enter.
[Solved!] How to Delete Old Time Machine Backups on Your Mac?
[Solved!] How to Delete Old Time Machine Backups on Your Mac?

Do you know how to delete Time Machine backups on your Mac computer? In this post, we will show you different cases and different methods.

Read More

Tip 4: Delete Browser Cache

Every time you visit a new web site using your web browser, some cache files will be created and saved to your Mac disk. This can help you to quickly a previous page again. But these files can also use up your disk space. So, you can delete these browser cache files to release more space on your Mac:

  1. Open your web browser.
  2. Click the History tab and then select Clear browsing data.
  3. Select the cache files you want to delete like Cookies, site data, Cached images and files.
  4. Choose how far back you want to delete
  5. Click the Clear browsing data button to delete the selected cache files.

Tip 5: Remove Language Packs

Most apps contain language packs (which are also known as localization files). These packs allow you to switch between languages when using the app. They are useful, but you need to admit that you only need one or two languages. The rest language packs just waste your disk space. You can choose to delete them:

  1. Open Applications.
  2. Right-click an app and then select Show Package Contents.
  3. Click Contents.
  4. Click Resources.
  5. Delete the language packs you don’t need to use. The pack files are ending in .Iproj.
  6. Repeat these steps for all other apps on your Mac.

Tip 6: Use Startup Disk Full Fixer

Startup Disk Full Fixer is the best free app for you to perform a quick Mac disk cleanup. It can help you to get more free storage space in less than a minute. You can go to the Mac App Store to free download this application. Then, you can open it and use it to clean up your startup disk to get rid of the low disk space warning. It is a safe program. You can feel free to use it.

How to Free up Disk Space on Your Mac?

Your disk is almost full is another alert that prompts you to clear disk space on your Mac computer. We have published a related article to free up disk space on Mac: How to Clear Disk Space on Mac and Recover Mac Data?

If you have some other good ideas to release disk space on Mac, you can share them with us in the comment. We will appreciate that.

When you receive a startup disk full or low disk space warning on your Mac, you can use the methods mentioned in this article to remove the alert.Click to Tweet

If You Delete Some Important Files on Your Mac by Mistake

As you can see, it is a file deletion process when you clear the startup disk on your Mac. During the process, you may delete some of your important files by mistake. Once these files are permanently deleted from your Mac computer, you will be unable to restore them from Trash. If you want to retrieve them, you can try the free Mac data recovery software: Stellar Data Recovery for Mac.

This software has a trial edition. You can use it to scan the Mac disk you want to recover data from and then check whether it can find the files you want to rescue. If yes, you can upgrade it to a full edition and then use it to recover all your needed files to a suitable location. You can go to the MiniTool download center to get this trial edition.

1. Open this software.

2. Select the data types you want to restore. If you want to recover all, you can turn on the button for Recover Everything.

3. Click the Next button to continue.

select the data types you want to recover

4. This software will list all the drives it can detect. Then, you need to select the drive you want to recover from. If you want to perform a deep scan, you need to switch the button for Deep Scan to ON.

5. Click the Scan button to start the scanning process.

select the target drive to scan

6. When the scanning process ends, you can see the scan results. By default, these files are list by Classic List. There are two other lists including File List and Deleted List. If you only need to recover the deleted files, you can switch to Deleted List and then find your needed items.

scan results

7. This software allows you to preview files. You can just double-click on one file to preview it and confirm whether it is your needed file.

8. If you are sure this software finds your needed files, you can go to MiniTool official site to get a license of an advanced edition to upgrade this software. After that, you can select files and then save them to a suitable folder. Here, you need to know that the destination folder should not be the original one. Otherwise, the deleted files could be overwritten and become unrecoverable.

Bottom Line

When your startup disk is full or you see the alert of your disk is almost full on your Mac, you can just try the methods mentioned in this article to free up disk space and remove the warning. If you mistakenly delete important files, you can use Stellar Data Recovery for Mac to get them back.

Should you have any related issues, you can let us know in the comment. You can also contact us via [email protected].

Startup Disk Full FAQ

How do I fix a Mac startup problem?
If you can’t boot up your Mac, there should be something wrong with the startup disk. This article tells you what you can do: What to Do If Your MacBook Won’t Turn On? (Multiple Methods).
How do I free up disk space?
If you want to free up disk space on a Windows computer, you can do the things mentioned in this article: 9 Ways to Clean up Disk Space in Windows 10.
Why is my hard drive still full after deleting files?
The deleted files will be removed to Trash before you delete them permanently or empty Trash. The files in Trash still occupy space on the drive. That’s why your disk is still full after deleting files. If you want to make some changes, you can open Trash and click the Empty button to permanently delete files in it.
How do I fix a stuck Mac loading screen?
If your Mac computer can’t past the Apple logo, you can refer to this article to solve the issue: [Solved!] MacBook Pro/Air/iMac Won’t Boot Past Apple Logo!
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